Oral-History:Eiichi Fukada

About Eiichi Fukada

Eiichi Fukada was born on 28 March 1922 in Kokura, Japan. He received the B.Sc. degree in 1944 and the D.Sc. degree in 1960, both from the Department of Physics, University of Tokyo. He was a research member at the Kobayasi Institute of Physical Research (KIPR), Tokyo from 1944 to 1963; British Council Scholar at the Department of Physics, Imperial College of Science and Technology, London from 1956 to 1958; Chief Research Member of the Biopolymer Physics Laboratory, the Institute of Physical and Chemical Research (RIKEN), Tokyo from 1963 to 1980; Executive Director of RIKEN from 1980 to 1984; Research Advisor at the Institute for Super Materials, ULVAC, Tsukuba from 1987 to 1998; and a member of the Board of Directors at KIPR from 1992 to 2002. He has been an advisor of KIPR since 2002. He was Visiting Professor at Gakushuin University, Tokyo in 1961-1980, New York University in 1965-1966, University of San Paulo in 1974, Technical University of Darmstadt and University of Constance in 1986. He has published about 250 papers in English and about 200 papers in Japanese. He received several awards from academic societies in Japan, the Galvani Award from the International Symposium on Electrobiology in 1989 and the Poiseille Gold Medal Award from the International Society of Biorheology in 1995. His research areas include piezoelectricity of biological and synthetic polymers, electrical stimulation of bone growth, and biorheology of blood and its clotting. Dr. Fukada discovered piezoelectricity in bone and initiated a field of research that is active to this day. He also found piezoelectricity in innumerable other biological materials including DNA.

In this interview, Dr. Fukada describes his childhood, his undergraduate research at the University of Tokyo in the final days of World War II, the founding of the Kobayasi Institute of Physical Research, and his early research on the elastic properties and piezoelectricity of wood. He discusses his meeting with Dr. Iwao Yasuda and their discovery of piezoelectricity in bone in 1957 and its long-term importance. He talked about his research at Imperial College and his return to Japan to obtain his D.Sc. degree from the University of Tokyo. He described leaving the Kobayasi Institute and his move to Riken where he carried out research on rheology, hemorheology, and biorheology. He discussed his research on electrical stimulation of bone growth with his collaborators in Japan and the United States, and his understanding of the electrical stimulation mechanism. He talked about his research on biopolymers and on piezoelectricity in poled polymers. He described his retirement from Riken in 1980 and his continued activities there on a more managerial level. The interview was concluded with a discussion of his numerous visiting professorships, his comments on future directions in his field, and his active research continuing to this day.

About the Interview

EIICHI FUKADA: An Interview Conducted by Sidney Lang, IEEE Ultrasonics, Ferroelectrics & Frequency Control Society, Tokyo, Japan, 3 December 2014.

Interview #683 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

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Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, IEEE History Center at Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 USA or ieee-history@ieee.org. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.

It is recommended that this oral history be cited as follows:

Eiichi Fukada, an oral history conducted in 2014 by Sidney Lang, IEEE History Center, Hoboken, NJ, USA.

Interview

INTERVIEWEE: Eiichi Fukada
INTERVIEWER: Sidney Lang
DATE: 3 December 2014
PLACE: Tokyo, Japan

Introduction

Lang:

This is an oral history of Dr. Eiichi Fukada. It is taken for the IEEE Ultrasonics, Ferroelectrics & Frequency Control Society. We are doing this at the Kobayasi Institute of Physical Research in Tokyo, Japan and today is the 3rd of December 2014. So I guess we can begin.

Early Years

Lang:

Good morning Eiichi. Ah, you were born on March 28, 1922 in Kokura, Japan. Could you tell me a little about your early school, childhood, and things that you liked to do?

Fukada:

I was born in 1922 at Kokura in Kyushu Island and at that time my father worked in a company called Toyotoki. The present name is Toto, and Toto is now a producer of shower toilet and also unit bath in hotel. So they produced a lot of different kinds of porcelain ceramics.

Lang:

That is interesting.

Fukada:

And he retired the company and he moved to Osaka and then Tokyo. So I accompanied him. So I attended primary school, secondary school and high school at Osaka, and then came to Tokyo because the permanent address of my father was in Tokyo. Also my aunt was living in the Ginza Street in Tokyo. So, ah, during the course of high school, I was greatly interested in physics. I was a just ordinary boy and I was not a social man and but I liked to read many books and so I want to learn physics. So I entered the Physics Department of the University of Tokyo because at that time it was the best school in Physics.

University Studies

Lang:

And then you did a project. Ah, there you did a project there, ah, on what subject. What was your research project?

Fukada:

Ah, oh, yeah.

That was just during the war time. The World War, the Second. So the period of lectures was usually three years. But it was shortened to 2 ½ years, but there was ordinary lectures. So at the time, Prof. Yukawa was very famous as a Nobel Prize Winner in Physics, so I attended his lecture on Quantum Mechanics.

Lang:

Aha.

Fukada:

But the lecture was so difficult.

Lang:

[Laughter]

Fukada:

Hard to understand.

And, at the graduation work, I took a course with Prof. Kaya. And Prof. Kaya was known a very good scientist for ferromagnetism and he moved just to the University of Tokyo from Hokkaido University. So my graduation work advisor was Prof Kaya. But very unfortunately since the war the manpower was not sufficient in the industries, so most students in universities and schools were all mobilized to go to factories and industries and to work for some products of the war.

So Prof. Sato, he was a famous professor of acoustics, but he also worked on military work at an institute called Kobayasi Institute of Physical Research… So Prof. Sato arranged four student of each department to come to his Institute. Including myself, so I could not finish graduation work under Prof. Kaya, but I came to Kobayasi Institute at the third grade of University, and I made a work to grow single crystals of Rochelle Salt and the final element of Rochelle Salt was produced as a sensor for a hydrophone which we used to detect the submarine.

Lang:

I see.

Fukada:

So, ah, I encountered for the first time Rochelle Salt as a university student and also I got to Kobayasi Institute. So that is the first of my life work on piezoelectricity.

Lang:

That is very important.

Fukada:

Yeah.

Lang:

It certainly was.

Early Years at Kobayasi Institute of Physical Research

Lang:

So then, ah, you continued working at the Kobayasi Institute.

Fukada:

Right. After graduation Prof. Sato invited me to join this institute as a research member.

Lang:

How did the war affect you?

Fukada:

In June 1945, I was called to the army and sent to a unit of antiaircraft gun troops located west of Tokyo. The duty of the unit was to prevent the air raids of the B29 bombers. The war ended on August 15th and I was fortunate enough to be released from the army at the end of August.

All houses my father owned were burned and he lost all of his assets. So my family lived in the narrow second floor of a farmer’s house near Kobayasi Institute. The space was formerly used to raise silk worms. Later, Prof. Sato kindly arranged for me to rent one of the employee’s houses built by the Rion Company, which was established by the Institute. The life after the end of war was very hard for everyone in Japan.

Lang:

And, ah, then I guess, after, you did some, ah…you began work in the acoustics laboratory and ah, studying wood.

Fukada:

Ah, yes. Aah.

Lang:

Oh you then started working under Dr. Kawai.

Fukada:

So, first I will explain about the Kobayasi Institute of Physical Research. Kobayasi is the name of an owner of a tungsten mine in Korea. And he was a very wealthy man, but he wished to establish a research institute for basic research in physics and life sciences considering the future development of Japan. So, ah, he encountered Prof. Sato of Tokyo University and he donated him a fairly large amount of money. I think it was about 10,000 US$ at that time. So, Prof. Sato collected many young good excellent scientists from various places all over Japan, for instance, Dr. Oka. Dr. Oka was a pioneer of polymer physics in Japan. It was about 1940, so at that time the polymer was regarded as heretical by most physicists. But Dr. Oka knew the importance for the interdisciplinary field is most important for the future research between the physics, chemistry and biology. Such interdisciplinary research, he encouraged to go into. So he was originally a theoretical physicist, but he made a good connection between many kinds of people so, he encouraged to investigate the blood rheology, the flow of blood in body is very important, so he was also the founder of Biorheology in Japan.

And Professor Sato collected highly talented chief scientists at Kobayasi Institute. The first one was Prof. Oka. The second was Dr. Kawai. And Kawai is a very famous, the founder of piezoelectric polymers, PVDF, and he was an excellent manager and also a scientist, and later I will talk about more related to PVDF. But he became a professor at Yokohama City University, and then he was elected Rector from that university. So he is a very original and also a very talented excellent scientist.

Then, one other, Professor, Miyake, and Professor Nomoto.

So Prof. Sato originally started the Japanese Society of Acoustics. So there, they have a Sato Award to give the young scientists who made a good contribution in acoustics.

Lang:

Oh, that’s nice.

Fukada:

So when I entered the Kobayasi Institute, this institute was just like graduate school at the University. And every Saturday we had a seminar, with all members and many people outside gathered too. So I think I got trained in a very good ideal atmosphere of education and research. So I owe very much to the excellent scientists of Kobayasi Institute of Physical Research. Actually, Dr. Kawai was my supervisor, so under his direction I started the research on piezoelectricity.

Piezoelectricity of Wood and Bone

Lang:

And originally then you started working with wood?

Fukada:

I worked with what?

Lang:

You worked with wood. You made your first measurements. Your first measurements were on the vibrational properties of wood, in the acoustics laboratory?

Fukada:

Oh wood, you mean.

Oh yes.

My first work in the Kobayasi Institute was the vibrational property of wood. So first I measured the dynamic elasticity and damping of wood plates including interestingly the very old timbers taken from the temples of Japan. We have many temples, 300 to 1300 years old in Japan. The oldest is Horyuji in Nara that is 1300 years old. Professor Kohara of Saikyo University in Kyoto gathered these old timbers for the study and I was fortunate to get me some parts. And I measured the elastic properties of these woods, and I was aware of the piezoelectricity of wood later. So at that time I investigated both elastic constants and piezoelectric constants for the old timbers. Both constants increased with the passage of time until 300 years, and then decreased until 1300 years. The values for 1300 years were almost same as those for wood recently cut in the mountain.

Lang:

That is interesting.

Fukada:

So there is an increase and decrease of elastic modulus and piezoelectric modulus with time in unit of 100 years. I think that both properties are closely related to crystalline properties of wood, so with time the wood may increase in crystallization so that the elastic modulus increases, piezoelectricity also increases, but at the same time, the heat dissociation, the natural degradation of cellulose takes place. So that decreases the elastic modulus and piezoelectric modulus. So in these studies I found the piezoelectricity simply related to crystalline properties. I also made an x-ray study to confirm these changes.

Lang:

It is very interesting.

Fukada:

Yeah. I am interested.

Lang:

It is unusual.

Fukada:

As a matter of fact, I will come back to the piezoelectricity of wood. So, but at that time, most people didn’t believe that wood had crystals and such material have piezoelectricity. Not many people believed it.

[Laughter]

But, I have curiosity so I wanted to write an article on piezoelectricity in wood. So I cut samples in many directions, and first I pressed using a lever and I put the foils on the sample of wood and the clamp with a galvanometer, and then I pressed the lever with a galvanometer, move it or not. I tried, but no such a success. It is a very small effect. So at that time Dr. Kawai gave me one suggestion: how about to use the dynamic measurement. So I originally worked on Rochelle Salt. Rochelle Salt is very sensitive piezoelectric crystal. So I made about one centimeter cubic wood and pressed it with Rochelle Salt crystals together by metal, metal frame. And then I gave an AC field to the wood. Then the wood vibrates, so that vibration could be detected by Rochelle Salt. It is really converse piezoelectric effect. And so, by this combination of wood and ceramics, if you use the AC field on Rochelle Salt, Rochelle salt vibrates, and that is transmitted to the wood, then the wood shows AC voltage due to the direct piezoelectric effect. That small voltage can be amplified and detected, so coupling this to Rochelle Salt we can show the direct effect and the converse effect at the same time. And the coefficient of the piezoelectric constant and converse piezoelectric constant agree very well. The force and polarization are linear and the electric field and the deformation are also linear. So when I saw this agreement of the direct effect and converse effect, I could convince that there is a piezoelectric effect in wood.

Lang:

Did you publish the results of your experiments with wood?

Fukada:

Yes, I published a paper, the piezoelectric effect of wood in the Journal of Physical Society of Japan in 1955.

In 1965, I was invited to talk at the Second Symposium on Nondestructive Testing of Wood, held at Washington State University, Pullman, USA. There, Dr. Galligan was using piezoelectricity for the purpose of non-destructive testing of Young’s modulus of wood. I gave a lecture there on the piezoelectric properties of wood from my past years. And after the lecture, Prof. Kollmann in Germany told me that I convinced him first time that the wood has piezoelectric properties after my lecture. And that was a very great compliment for me, because Prof. Kollmann was the most distinguished wood physicist in the world. So later Prof. Kollmann founded the International Academy of wood Sciences, and he invited me to the First Symposium at Salzburg in Austria. And I was invited to give a lecture there. So I will never forget the Mozart Music School with its park of beautiful flowers. He then convinced me, belatedly, to continue my research.

Later, the research on the piezoelectricity of wood has been earnestly continued by Prof. Hirai of Shizuoka University. And many other people also made the piezoelectric studies of wood.

Lang:

Your meeting with Dr. Iwao Yasuda and his suggestion that you jointly study in bone was profoundly important in directing your future piezoelectricity work. Please tell me how you met him and how the research developed.

Fukada:

It was my great fortune, that I met Dr. Iwao Yasuda in 1956. At that time he was Associate Professor of Orthopedics, Kyoto Prefectural University of Medicine. He had read my paper on the piezoelectricity of wood and came to the Kobayasi Institute from Kyoto to see me. And he explained that he observed that the electric potential appears when the bone is bent. He proposed the collaboration of research for piezoelectricity on bone. And so I had gladly accepted. I believed that bone should have a piezoelectric effect, because wood and bone both have a related structure of plant and animal. So I could use the same apparatus which I used on wood and I found the shear piezoelectric effect in bone similar to wood, about twice as large as dried wood.

Ah.

Originally we could observe only shear piezoelectricity. That means when the shear is given to the oriented sample of collagen fibers, the polarization takes place in the perpendicular directions to the shear plane. That is called shear piezoelectricity. The same as was observed in wood and bone.

But later we examined the anatomy not only in bone, but in Achilles tendon. The Achilles tendon consists of almost 90% very rarely oriented collagen fibers, and there we found not only the shear effect, but also longitudinal piezoelectric effect. If I give the elongation or shrinkage in the direction of orientation, the polarization appears perpendicular to the direction to the section or in the same direction of elongation. So the finding of elongation of piezoelectricity means that there is polarity in the collagen crystal or collagen molecules. So finally I could decide the seven piezoelectric constants, including shear and longitudinal effects.

And then, 1966, Prof. Sidney Lang, currently of the Ben-Gurion University of the Negev, Israel, reported in Nature the pyroelectricity in bone, which indicated the existence of polarity in bone. And in 1970, Prof. Athenstaedt of Kiel University, Germany, also published the pyroelectric effect in many vertebrate skeletons and showed the relation between the direction of polarity and the direction of development of the structure.

Lang:

You published the results in your paper in 1957, a very, very famous paper. Do you know how many times it has been cited?

Fukada:

Oh yes, very fortunately, my paper with Dr. Yasuda was published in Journal of Physical Society of Japan in 1957. It was referenced very often, and according to the Google Scholar Citations, the number of citations was over 1000.

We also published the piezoelectricity in collagen in Japanese Journal of Applied Physics in 1964. Its number of citations was 260.

Lang:

That is amazing.

Fukada:

So when I studied wood and collagen, I thought there would be many other biological materials which should have the piezoelectric effect. So I tried different kind of samples and conditions: ramie, hemp, wool, silk, hair, skin, and later, muscle, DNA so on. And I published a short paper on the piezoelectric effect in silk fibers in the Journal of Physical Society of Japan in 1957.

And it was cited as 'Electric Silk' in the column of New Scientist, a journal in England. And at that time I was in London as a British Council Scholar. So my supervisor, Dr. Charlesby was excited, and called the newspaper, but nothing happened.

[Laughter]

Imperial College

Lang:

You decided to go to Imperial College in the course of your work on bone with Dr. Yasuda. What caused you to decide to continue your studies at this time? Why did you choose Imperial College?

Fukada:

So in 1950-1960, the peaceful use of atomic energy was a very hot problem in Japan, and Dr. Charlesby in the Atomic Energy Establishment, Harwell, England started a work on the modification of structure of polymers by high energy irradiation. So I was very bold to write a letter to him and then he very kindly sent me a sample polyethylene rod irradiated by Harwell’s atomic pile. So, I was so delighted and measured the dynamic elastic constant and I found that these samples changed from the normal classical state, first to a rubbery state and then to a glass-like state with the increase of radiation dose. And also I found that triboelectricity was changed from negative to positive according to the dosage. This is a very interesting problem and not really solved yet.

Lang:

[Laughter]. Very interesting.

Fukada:

So I applied the British Council Scholarship and very fortunately passed the examination. So British Council elected at that time about 10-15 students from science and also from law and economics. And we had to go to England by boat. No airplane. The boats called at many places. So we could visit Hong Kong, Singapore, Penang, Bombay, Aden, Suez Canal, and finally London. So we enjoyed very much to see the world.

The British Council arranged for me to stay at Imperial College. The supervisor was Dr. Stephens. He was a Reader of Acoustics in the Physics Department. So the people in Kobayasi Institute know very well Dr. Stephens. And fortunately, he was a friend of Dr. Charlesby. So I belonged to the laboratory of Dr. Stephens and I studied the viscoelastic properties of polyesters irradiated by Co60 gamma ray and high density polyethylene irradiated by Van de Graff electron accelerator in the laboratory of Dr. Stephens, keeping close contact with Dr. Charlesby. I stayed at Imperial College for about 15 months, and then returned home through the United States. I again took a ship, so two weeks Atlantic Ocean….no, just one week across the Atlantic, and two weeks across the Pacific Ocean.

Lang:

So then, you came back in 1958, to the Kobayasi Institute?

Fukada:

Yeah, 1958 I came back to Japan and again I worked at the Kobayasi Institute.

Doctoral Studies

Lang:

Aha. And then you began your doctoral studies?

Fukada:

Oh, oh, ah, yes.

Well, in 1950-60, there was a big change in the educational system in Japan, including the doctorate system. For a new system, one should stay in graduate school of the university for three years, and write a thesis and submit for evaluation in doctorate, and then given a Ph.D. It is the same style as that in the United States. But in the old system, it was not necessary to stay at graduate school. You can carry out research at any place outside of university. And then if you could get good papers published in the qualified journals, then you can provide these papers to the university, and get examination and finally get a Doctor of Science.

So I followed the old system. So I submitted my papers on the vibrational properties of wood, the piezoelectric effect of wood, and the piezoelectric effect of bone, to the Department of Physics, the University of Tokyo, and was given a Doctor of Science.

Lang:

Did you ever consider teaching in the University?

Fukada:

Oh, there were several possibilities when I was in Kobayasi Institute. Yes, I was invited from the University, but during the stay in Britain, I was paid by the Kobayasi Institute and I liked very much the research atmosphere of Kobayasi Institute, so I wanted to stay here as long as I can make research.

[Laughter]

So I declined the several invitations.

KIPR and RIKEN

Lang:

Aha, I see. Now you worked at Kobayasi Institute [Kobayasi Institute of Physical Research (KIPR)] until 1963 and then you went to RIKEN [Institute of Physical and Chemical Research]. Can you tell me about the two?

Fukada:

Oh, I see, yeah.

Very unfortunately, after the war, there were many economic problems. Mr. Kobayasi has lost his entire assets because his mine was in North Korea. So, accordingly, the Kobayasi Institute also had lost its economic ground. So Kobayasi Institute tried to establish a company. Now it’s called Rion. And Dr. Kawai was an excellent scientist and also engineer. So he used the Rochelle Salt piezoelectric crystals and he made several kinds of products including a sensor for microphones and such kind of products using piezoelectric materials and also acoustic measuring apparatuses. And also, the entire economy was not so good. So, on the other hand, in 1950-60, many new universities or institutions were built in Japan. So the young scientists educated in this institute moved to other universities as professors or assistant professors. So there was a big change from the basic research to more engineering or useful research, research useful for society. So what remained was acoustics and piezoelectrics. So, I remained at this institute to continue the piezoelectricity, but fortunately I got invitation from Riken, because in Riken, people were considering the peaceful use of atomic energy, and they built a Research Institute for Radiation Polymers very close to Riken. Dr. Shinohara was the president of that institute and he kindly invited me to come to Riken. So I considered. So I decided to move from Kobayasi Institute to Riken. But when Dr. Shinohara retired, I became a chief research scientist in Riken. And since the new chief scientist can determine the name of his own laboratory, I decided the name of the laboratory as Biopolymer Physics Laboratory.

[Laughter]

There I can do any kind of research, polymer, biopolymer, dependent on physics.

Lang:

That’s nice. Very good.

Fukada:

But the Kobayasi Institute also developed in the area they wanted. The acoustics is very important in science. It is applied physics and very useful for many problems to be solved in society. So, for instance, the conventional noise, or measurable noise are very important in airports, transportation, boat, houses, and many problems related to research, and the possibility of contract research with industries or government organizations. So, I think that Kobayasi Institute and Rion are very important research institutes in the field of acoustics, and they have good scientists in the Physical Society and Acoustical Society of Japan, and are making great contribution for the many problems of society.

After retirement from Riken, I was fortunately invited to come back to Kobayasi Institute [KIPR] in 1991. Since then I have been working in KIPR. Piezoelectricity has been a small but important part of activities of KIPR.

Lang:

Just a small part.

Fukada:

But acoustics is a very basic field of physics, so there are many problems that must be solved by the basic physics. For instance, the isolation and attenuation of sound is a very important and difficult problem. Recently we have a new technique to modify the elastic properties of piezoelectric materials, PVDF or PZT, by connecting a feedback circuit, called a negative capacitance circuit, for the purpose to control the propagation of sound.

If a large plate or film of PVDF is changed to a hard iron plate, the sound is totally reflected, and the sound will be insulated. On the other hand, for the underwater propagation of sound, you put a PVDF film inside water and connect a circuit to decrease the elastic modulus of PVDF. If the elastic modulus becomes near zero like vacuum, then the underwater sound is completely reflected. So for airborne sound and underwater sound, we need two different feedback circuits to change the elastic modulus of piezoelectric materials, either PVDF or PZT. And my colleague, Dr. Date found the original idea and succeeded to make two kinds of negative capacitance circuits. I hope soon we will publish the results.

Lang:

That’s wonderful. That’s amazing.

Fukada:

So I am very happy that Kobayasi Institute is developing as a very original institute for acoustics in Japan.

Lang:

That’s important. That is very important.

Rheology, Hemorheology, Biorheology

Lang:

When you returned from Imperial College, you did research in rheology, hemorheology and biorheology. With whom did you work?

Fukada:

So, in the recovery period of Japan, the interest in rheology aroused in both academic and industrial circles. Rheology is the science of flow and deformation, important in chemical industries. Prof. Oka was interested first in rheology in polymers, then the flow properties of blood. He developed mathematical theories on the flow of blood and the deformation of blood cell walls. He encouraged the studies in the boundary regions of physics and biology, interdisciplinary fields. I was inspired by him to enter the field of biorheology. I was fortunate to have a co-worker, Dr. Kaibara, who entered my laboratory at Riken. By the help of Dr. Date we could build a new rheometer which records the time change of dynamic modulus and damping during the clotting of blood and of fibrinogen and thrombin systems. Later this became a life-long research work for Dr. Kaibara. Dr. Isogai of Tokyo Jikei University of Medicine and Dr. Azuma of Juntendo University visited Riken and the interaction with these medical people increased. Prof. Al Copley of New York University, famous as a founder of Biorheology, visited Japan and talked with Prof. Oka and Prof. Tamamushi. In 1977, the Japanese Society of Biorheology was established by the efforts of Prof. Oka and his group.

Lang:

You were active in the International Society of Biorheology and served as its president. Tell me about it and your organization of the 4th International Conference of Biorheology in Tokyo in 1981.

Fukada:

In 1981, the International Congress of Biorheology was held in Jikei University in Tokyo, and I was president. I wish to thank the earnest help of Prof. Isogai, Prof. Copley, and many other scientists.

Lang:

You had a long association with Dr. Munehiro Date. How and when did this association begin? In what areas did you collaborate?

Fukada:

I like to talk about Dr. Date. He is my indispensable cooperator. In 1959, he joined to my laboratory as a fourth-year student of Gakushuin University. Since then, he is my best collaborator in my entire career. He is very ingenious, very gentle, and full of original ideas. He has a deep knowledge in electronics and mechanics. He has produced many experimental apparatuses and helped other researchers. An automatic recording apparatus for the complex elastic, dielectric and piezoelectric constants as a function of frequency and temperature is the most famous. It was commercialized by a company and sold over 100 pieces in and out of the country. So he is a wonderful person. I am very grateful to him for his most useful cooperation and life-long friendship.

Lang:

In your autobiography published in Reports on Progress in Polymer Physics in Japan in 1995, you mentioned Prof. Alfred Copley of the Polytechnic University of New York. He was famous both for his research in biorheology and as a well-known painter. Please tell me about him.

Fukada:

I met Prof. Copley many times. When I visited New York City, I always visited his home at Central Park. He was enthusiastic with biorheology, but also he was a famous painter. His pictures always reminded me something related to the flow of the liquid. He was very kind and taught me the international behavior of scientist. When I went to see the exhibition of his paintings in Ginza, Tokyo, he was talking with famous Mr. Taro Okamoto, a famous painter in Japan. I treasure a book for his memory, ‘One Man and Two Visions’. I have a picture of this book.

Lang:

I would like to see that.

Electrical Stimulation of Bone Growth

Lang:

In 1965 and 1966, you worked in the Physics Department laboratory of Prof. Shamos of New York University. The research on piezoelectricity in bone involved many people including Professors Lavine, Bassett and Becker. Please tell me about your interaction with them.

Fukada:

So, after I and Dr. Yasuda published the paper on piezoelectric effect in bone in 1957, Prof. Shamos in the Department of Physics of New York University started also to study the piezoelectric effect in bone together with Prof. Lavine, who was a professor of orthopedics at the State University of New York, Downtown Medical Center. I was lucky to be invited as a Visiting Professor in Prof. Shamos’ laboratory. They concluded that the piezoelectric effect was originated from the crystalline properties of collagen. That was the same as my interpretation. Prof. Bassett of Columbia University and Prof. Becker of State University of New York, Upstate Medical Center, Syracuse, proposed a mechanism of p-n junctions between the collagen and hydroxyapatite. And this theory was not accepted at that time. But now in 2011, Prof. Lang and Dr. Tofail of the University of Limerick, Ireland, proved the piezoelectric and pyroelectric effect in hydroxyapatite crystals. So the investigation of interfaces between collagen and hydroxyapatite and their interaction should be an interesting object of research.

Lang:

In 1965 Dr. Iwao Yasuda traveled to New York University while you were there. Please tell me about the idea of using a piezoelectric film to induce callus formation in bone.

Fukada:

Dr. Yasuda visited me while I was in the New York University. And, he tried to show how to induce callus in a chick bone by flowing the DC current of about 1µA. During his visit to New York we met the blackout of electricity. [Laughter] And so we stepped down the stairs with a flash lamp. He had to stay one night in the lobby of Fifth Avenue Hotel. I climbed up stairs to my room at 15th floor …[Laughter]… and came down again with sandwiches to deliver to him.

Lang:

That must have been a very tiring experience.

Fukada:

Very nice experience.

[Laughter]

Dr. Yasuda has a confidence that the applying of electricity induces new bone called callus. We discussed how to demonstrate it. Our conclusion is to implant a Teflon electret film around the femur of rabbit, in vivo. The Teflon film is a good insulating plastic. By applying corona charge, stable surface charges are induced, one plane positive, the reverse surface negative. By bending the film, the apparent piezoelectric effect appears. So later, we published a paper in 1975 which showed a bridge-like callus clearly formed over the electret film. Later, many papers have been published on the bone formation by implanting piezoelectric polymer films. For example, Prof. Inoue in 1975 poly-γ-methyl-L-glutamate piezoelectric film for the femur of rat; Prof. Hayasi, 1979, PMLG for the fibura of rabbit; Prof. Suzuki, 1976, PVDF, femur and mandible of monkey; Prof. Matsusue, 1991, poly-L-lactic acid screw, rabbit fibular; Prof. Ikada, 1996, PLLA, intramedullary nail, that’s a rod, tibia of cat; and Prof. Shimono, 1996, PLLA film, tibia of rabbit.

So we have so many examples of the effect of implanted polymer, piezoelectric polymer can induce the growth of new bones.

Lang:

It was important work.

Fukada:

Yeah.

Lang:

Can you tell something about the 1973 Symposium on Electrically Mediated Growth Mechanisms in living systems?

Fukada:

In 1973, the New York Academy of Sciences organized a Symposium on Electrically Mediated Growth Mechanism in Living Systems. I talked about research on the piezoelectric properties of biopolymers such as polypeptides and DNA for the past ten years. Dr. Yasuda also gave a talk on his discovery of the bending piezoelectricity in bone and electrical growth of bone. His talk was received with great interest. In 1975, in the SICOT orthopedic conference, Dr. Yasuda also gave a talk on his original work on electrical stimulation of bone and received great appreciation among orthopedic surgeons in the world.

Lang:

Dr. Eriksson described the concept of streaming potential as an alternative mechanism for the electrical effects in bone. What was your opinion about this controversial issue at that time and is it different today?

Fukada:

In 1968, Dr. Erickson of Imperial College in London indicated the importance of the streaming potential in bone and tendon. In 1975, Prof. Pollack of the University of Pennsylvania presented beautiful results to show the streaming potential in bent moist bone. When bone is bent, the body fluid flows from the compressed region to the expanded region. The ionic fluid flows through canaliculi which penetrate the matrix of bone, that is, ground substance. The major origin for the electric potential in bent wet bone was ascribed to the streaming ionic potential rather than the piezoelectric potential.

Well, these are interesting discussions.

Lang:

It was a very hotly debated topic; a lot of discussion.

Fukada:

Oh yes. Oh yes. And then, I have my own conclusion from my own imagination.

In 1982, Dr. Maeda of Research Institute for Polymers and Textiles, Tsukuba, published the relation between the piezoelectric constant and the humidity content for bone and tendon collagen. The piezoelectric constant for tendon decreases with water content to zero at 30% fluid content. The highest water content of wet bone is about 10% and the piezoelectric constant measured for bone with 10% water content was finite, not zero, but actually 0.05 pC/N. The piezoelectric constant for collagen fibers inside the matrix of bone with 10% water content was 0.25 pC/N. Again it was finite.

Lang:

Aha. Very small!

So what do you believe is the mechanism for the interaction of electric fields and bone?

Fukada:

So my explanation at present is as follows: The externally applied stress on bone is transmitted to the collagen fibers in the matrix. The crystalline region of collagen fibers produces the piezoelectric polarization, but this polarization induces the ionic cancelling current surrounding the collagen crystallites. If the applied stress causes the pressure difference in canaliculi, the liquid flow takes place and the streaming potential is produced. So both mechanisms may exist. The piezoelectric potential is produced mainly by the shearing force and the tensile force, but the streaming potential is mainly caused by the bending deformation. The most interesting problem is the mechanism how the electric current reacts with the bone cells.

Lang:

That still isn’t very well understood now. What about the use of external electrical stimulation for healing nonunion fractures of bone?

Fukada:

So following the discovery of electric callus of Dr. Yasuda, the investigation for the clinical device to heal the bone fracture has been developed by several orthopedic surgeons. In 1974, Prof. Bassett of Columbia University started to use pulsed electromagnetic field. In 1981, Prof. Brighton of Pennsylvania University invented capacitive method using AC current at 60 kHz. In 1983, Dr. Duarte started the application of pulsed ultrasound. Various commercial instruments have been produced and used for the clinical treatment.

Lang:

They are still in use today?

Fukada:

Yes. Particularly the ultrasound method is very popular.

Lang:

Aha.

You were a founding member of the Bioelectrical Repair and Growth Society (BRAGS) that is now called the Society for Physical Regulation in Biology and Medicine (SPRBM). What are some of its activities?

Fukada:

In 1980, the Bioelectrical Repair and Growth Society, called BRAGS, was founded in Philadelphia. Now it is called the Society for Physical Regulation in Biology and Medicine. In Japan, in 1976, Dr. Yasuda and I founded the ‘Japanese Committee for Electrical Enhancement of Bone Healing’. That very small group has developed now to the Japanese Bio-Electrical and Physical Stimulation Research Society, which had the 40th annual meeting last year in Yokohama.

Lang:

Aha.

Fukada:

In Riken, I was fortunate to work with biologists, Dr. Kaneko and Dr. Takahashi. We examined the effect of pulsing electromagnetic field on the proliferation of fibroblast bone cells... It was cultured… and fibroblast cultures. We changed the wave form of the pulse and obtained optimum conditions. The optimum pulse width was 25 µsec, and the optimum frequency was 10 Hz. Similar effects were also obtained by Prof. Matsunaga in Kagoshima University, for the growth of rabbit femur and Prof. Masaoka in Tokyo Medical University for the DNA synthesis in cultured bone cell using the same apparatus.

Lang:

Aha.

Fukada:

So three different researchers at three different places made the work and they all reached the same conclusion that a special pulse width 25 µsec, and a special frequency around 10 Hz are most useful for bone cell culture and for callus formation.

Lang:

That’s interesting.

Fukada:

So I am extremely interested.

Lang:

So you really optimized it. Interesting. That’s fascinating.

Fukada:

So the point is, this 25 µsec or 10 Hz means what?

Lang:

What does it mean? Why?

Fukada:

It might be the… This is a very important problem. Why the electricity start the biochemical reaction inside the cell. And for that purpose, there are many factors. But one reason is that calcium ions are introduced through membrane proteins by the action of the electrical or mechanical stimulus. Prof. Sokabe of Nagoya University personally suggested me that it might be related to the time to activate calcium ions to the amount necessary for bio-reaction. I vaguely imagine that there might be a time for ions to flow in and out through the membrane to reach the equilibrium potential difference. This is only speculation.

Lang:

It is interesting speculation.

Fukada:

[Laughter]

So many studies have been carried out on culture of bone cells to understand why an electric field affects bone. One possible explanation is that an electric field on the surface of cell membranes changes the electrification of the ion channel protein. Protein molecules composing the ion channel may have also the helical structure and so may have piezoelectricity. The change of conformation of protein may alter the penetration of ions such as calcium or potassium, which affects the succeeding biochemical reactions. The increase of calcium ions is experimentally confirmed under both electrical and mechanical field.

Lang:

That is a nice concept. Very good, very good!

San Carlos, Brazil

Lang:

Can you tell me about your visit to the laboratory of Prof. Mascarenhas in Sao Paulo, Brazil in 1974?

Fukada:

In 1974, Prof. Mascarenhas invited me to be Visiting Professor at the Institute of Physics and Chemistry at San Carlos, University of Sao Paulo. I stayed in San Carlos from April to September and I gave a lecture on the piezoelectricity of electrets. And I worked also with Prof. Zimmerman to set up an apparatus to measure the dynamic piezoelectric constant. Prof. Mascarenhas asked me to obtain a photograph of Prof. Eguchi. So I wrote a letter to his son and got a photograph of Prof. Eguchi and his wife at the wedding ceremony.

Lang:

Amazing.

Fukada:

So the photo is now on display on the wall of the Institute of Physics and Chemistry, San Carlos. Prof. Gross had his home in San Carlos. He has kindly sent me his book, The Theory of Viscoelasticity, while I was in Japan. During my stay at San Carlos, I could meet Dr. Duarte of the Department of Orthopedics, University of Sao Paulo at Riberon Preto. He studied fracture healing by pulsed ultrasound, which seems more popular than electrical stimulation at present. Later Prof. Mascarenhas visited Japan and stayed in Riken. He wished to have a close connection of research between Brazil and Japan. In 1980, the ‘First Brazil-Japan Symposium on Science and Technology’ was held at Rio de Janeiro, Sao Paulo and San Carlos.

Lang:

Did any of the other people from San Carlos visit here?

Fukada:

Ah, yes. Dr. Zimmerman also visited and he came here and stayed a few days. So we have many good friends in Brazil.

Piezoelectricity in Biopolymers

Lang:

Yes. Then you did some work on biopolymers?

Fukada:

Oh, yes.

I have started my study on piezoelectricity on wood and bone, representing plant and animal. If there is a chiral structure in the molecule, the shear piezoelectricity may be possible. If there is a polar orientation in molecules, the tensile piezoelectricity may be possible. And, I am greatly interested in Wolff’s law in orthopedics. ‘Bone grows best to support the applied stress.’ This is Wolff’s law. One time the piezoelectric current from collagen produced by applied stress was considered to be triggering signal for this Wolff’s law. More activity of osteoblast or osteoclast occurs where more activity of either mechanical or electrical stimulation exists. Mechanical and electrical fields are transformed by piezoelectric effect in collagen or ionic flow in canaliculi under pressure difference. I think to elucidate the mechanism of Wolff’s law should be a very charming target of future research.

Lang:

Are people working on it today?

Fukada:

Well, I feel not so much. They have a great interest. The orthopedic people have a direct interest, but to me they are too busy to make such basic research. So, I feel we need some cooperation between the basic scientist and the orthopedist.

Lang:

Yes.

Fukada:

In that sense, it is a very charming kind of research.

Lang:

Yes, I can imagine. There is a lot to be learned there.

Fukada:

In the extension of cellulose and collagen, the shear piezoelectricity has been studied in many optically active polymers, such as DNA and Poly-L-Lactic acid, PLLA. I have found the shear piezoelectricity in PLLA in 1991 and Dr. Tajitsu, who last joined to my laboratory in Riken and is currently professor of Kansai University, developed the shear piezoelectric constant of PLLA near that of PVDF. He made collaborations with several companies. The examples of products already known are remote controller for TV, pressure sensor, piezoelectric fabric which controls the robots, and possibly smartphone in future.

Piezoelectricity in Poled Polymers

Lang:

You have done some work on… Of course, poled polymers are very important and the original work of Dr. Kawai.

Fukada:

Ah, yes.

Dr. Heiji Kawai of Kobayasi Institute originally worked on Rochelle Salt. In his laboratory, many young scientists worked on piezoelectric crystals. Among others, Dr. Marutake and Dr. Ikeda, who are my friends, worked very actively on barium titanate and lead zirconate ceramics, and later moved to universities.

Dr. Kawai has been always busy to help the development of Rion Company as the director of the technical division. However, five years before retirement, he left all responsible positions and devoted himself to find a new type of piezoelectric polymer. He combined the elongation and poling to give the piezoelectric properties to various types of polymers. So I helped him by supplying the various polymer samples. He built the equipment by himself and made all measurements by himself. He published his discovery on the tensile piezoelectricity in poled films of polyvinylidene fluoride, 11-nylon, polyvinyl chloride, polytetrafluoroethylene and others in Japanese Journal of Applied Physics in 1969. And the magnitude of PVDF became larger and larger and finally now is near 20 or 30 pC/N. So it is very convenient for the industrial use.

Lang:

Yes, indeed.

Fukada:

Actually, I feel that Dr. Kawai and Dr. Yasuda resemble to each other. Both have great originality and ability to look at the core of nature. Dr. Kawai and Dr. Yasuda and Dr. Oka have given me the deep influence and I sincerely thank them.

The studies of PVDF and its copolymer with polytetrafluoroethylene have become the most active subjects in my laboratory in Riken. Dr. Furukawa has made a major contribution to establish ferroelectricity in polar polymers by his theoretical and experimental work. PVDF and its copolymer are now widely used in industrial applications such as sensors and transducers. I would like to mention shortly about polyurea, which I worked on with Dr. Yoshikazu Takahashi at the Institute for Super Materials, ULVAC, after my retirement from Riken. Urea bond has a dipole moment as large as 4.9 Debye. So by the technique of vapor deposition polymerization of two monomers, polyurea is simply formed on the surface of solid materials. After poling charging, it becomes pyroelectric and piezoelectric, enduring the high temperature of 200ºC.

That is probably the highest temperature that piezoelectric polymers can stand.

Lang:

Is it much used today? Are there applications?

Fukada:

Ah, Dr. Takahashi developed many kinds of applications. So I don’t know the details, but if they need a high temperature piezoelectric, this polymer can be used. So, these are industrially good polymers.

Lang:

That is good to know. There really isn’t that much information about it.

RIKEN

Lang:

So, I guess things changed at Riken?

Fukada:

Yes. I moved to Riken and I stayed there for about 20 years. I just spent 20 years in Kobayasi Institute and another 20 years in Riken.

Riken is the abbreviation of ‘Rikagaku Kenkyusho’ in Japanese. English name is The Institute of Physical and Chemical Research, but Riken is now officially used even in English.

Lang:

Aha. I see.

Fukada:

Prof. Tomonaga, a famous Nobel Prize Medalist in elementary particle physics, once said that Riken is a paradise of scientists. And, it was established in 1917 by the government. Most scientists wish to work in Riken rather than in universities. There is a freedom for basic research, and no duty of teaching. So the chief research member may have several staffs to work together. So, my friend, an orthopedist in a hospital told me, ‘I can do research only in the evening after the treatment of patients in daytime. But you can do that 24 hours.’

[Laughter].

Lang:

That’s rather like in the university. It would be a great place without the students. Then you could do the research all the time.

Fukada:

Oh yes.

Fukada:

The chief scientist can decide the name of the laboratory. So I named my laboratory as Biopolymer Physics Laboratory. So I could do anything with polymer and biorheology for physics. But the main themes were piezoelectricity and biorheology. I was fortunate to be a guest professor at the Physics Department of Gakushuin University from 1961 to 1980. I gave a lecture on polymer physics there. For that reason, students in the fourth year and graduate course came to my laboratory in Riken every year to do research work. Gakushuin is known as a school where royal families attend. The contributions to research of these students were very large and some of them got Ph.D. in Gakushuin University. I had also good staff scientists. Dr. Date has invented many experimental apparatuses to measure the dynamic behavior of viscoelastic and piezoelectric constants of polymers. Dr. Furukawa developed both experimental and theoretical studies on polymers, particularly on PVDF and its copolymers. He organized the Thirteenth International Symposium on Electrets in Tokyo in 2008. Dr. Kaibara has continued his research on the clotting of blood. He received the Oka Medal from the Japanese Society of Biorheology. The late Dr. Takamatsu worked on electret, thermally stimulated current in various polymers, and he took care of many students from various universities for their graduation work.

Lang:

Then you came to retirement in 1980, and became Executive Director for Life Sciences at RIKEN. In particular, can you mention the political problems resulting from the development of the recombinant DNA biotechnology laboratories at the Tsukuba Research Center?

Fukada:

Yes.

When I reached retirement age of 60, President Tatsuoki Miyajima appointed me as Executive Director of Research in Riken. The Agency of Science and Technology, to which Riken belongs, had been planning to build a new research laboratory on the recombinant DNA, as a branch of Riken. The location of the facility has been decided in Yatabe town in Tsukuba City. Tsukuba is a newly built city about 50 kilometers northeast to Tokyo. It is called the Science Garden City. Tsukuba University and many research laboratories of government and industries were built there. In the plan of new facility of Riken, the construction of P4 laboratory was included, which has the highest security against disease germs. In 1981, the people in Yatabe town had almost no knowledge of recombinant DNA and also P4 laboratory. So it seemed to be a very dangerous facility and the strong opposition movement started. Therefore, I had to open many meetings with people and explain the safety of the new facility. The approval of the town assembly was necessary. I visited my friends in University and the research institutes in Tsukuba and gathered the signatures of approval. This kind of event continued several years after I finished my four-year term. But, fortunately, gradually, the problem has been solved. So, at present the Tsukuba branch of Riken is called as Bioresources Center, which keeps and distributes the standard of kinds of microorganisms and cultured cells to distribute to researchers in Japan. No P4 laboratory there.

Lang:

This was your entry in politics in a sense, the politics of trying to convince people that something can be done.

Fukada:

Yes, but this is a problem. Politics! It is a very, very big problem.

So yes, Prof. Miyajima once told me that, ‘I gave you troubles’.

[Laughter].

But I am thankful to him, because he has a great interest in my work and encouraged my participation in scientific meetings abroad. I could enjoy about 20 years’ research in an ideal atmosphere in Riken. Then I went out to society and learned many things. The human relationships are most important in the society.

Retirement and Visiting Professorships

Lang:

So then you really began to retire.

Fukada:

Yes. After retirement, Prof. Sessler and Prof West are well-known as the inventor of the electret microphones at Bell Laboratories. By the introduction of Dr. Murphy, who owns a company producing microphones in Singapore, I was invited in 1986, by Prof. Sessler to his laboratory at the Technical University of Darmstadt. I gave a lecture on piezoelectricity and made an experiment on bending piezoelectricity of PVDF copolymers. There, I was impressed that all German students and the secretary spoke good English. So, actually, I lost a chance to practice my German.

[Laughter]

Lang:

A loss!

Fukada:

After the stay at Darmstadt, I was happy to be invited by Prof. Dransfeld, in the University of Konstanz. It is located by a very beautiful lake. And I and my family enjoyed very much the stay at Konstanz. We could visit Switzerland by bus without a passport. And I was also happy to be invited by Prof. Arlt at Technical University of Aachen. So I had the experience of life under a very cold climate in January and February of 1987 in Germany.

And also, in 1988, I had an unexpected fortune by the invitation of Prof. Liepsch in Germany to Eisenhower Medical Center, Palm Desert, Southern California, USA.

Lang:

Quite a difference in climate, much warmer!

Fukada:

So at that time, Prof. Liepsch was the director of the research laboratory of this hospital. So I worked on the viscosity of suspensions of polystyrene microspheres aiming at a model of blood. I just enjoyed that warm weather and the beautiful golf courses surrounded by pretty houses.

Lang:

Then you continued to go to conferences?

Fukada:

In 1989, I was invited to present a lecture at the Symposium Electrobiology Today to honor Luigi Galvani held at Bologna, Italy. I talked about the piezoelectricity in bone and DNA. At the banquet, my name was suddenly called and I was given a certificate of Galvani Award. It was a great surprise. And besides me, Prof. Bassett and Prof. Polack from USA, Prof. Chiabrera and Prof. Traina from Italy were given Galvani Award. It was quite an unexpected honor for me. I feel it is on behalf of Dr. Yasuda.

I feel I have not much contribution to the research on the rheology of blood. I worked with Prof. Oka for the development of the Society of Biorheology in Japan. I put more energy to piezoelectricity than to rheology. However, the famous rheologist, Prof. Scott Blair and Prof. Copley appreciated my work on piezoelectricity in biopolymers and gave a name, ‘electro-biorheology’. In 1981, I was president of the ‘Fifth International Congress of Biorheology’ in Tokyo and also, honorary president of the ‘Eighth International Congress of Biorheology’ , which was organized by Prof. Isogai at Yokohama in 1992. The ’Ninth Congress of Biorheology’ was held in Big Sky, USA in 1995. There I was given the Poiseuille Gold Medal. I gave the award lecture on the piezoelectric biopolymers. One of the audience said to me that this is the problem of basic physics and I was very pleased. I am very grateful for the help of Dr. Oka, Dr. Copley, and Dr. Isogai.

Conclusions

Lang:

So now tell me a little about your philosophy. I think that that is very important.

Fukada:

Yes. I would like to say that one should look at what is most important in the problem, what is the core, the center of the phenomenon in nature. I would recommend finding new subjects in the interdisciplinary field between physics, chemistry, biology and many other professional fields. Prof. Copley said that biorheology is the link between life sciences. And it is also important to have good relationships with people in many different fields. The work is not completed only by oneself. The cooperation is most important to accomplish a work.

Lang:

What do you think will be the big questions and issues facing your fields of research in the coming years?

Fukada:

The recent progress of piezo-response force microscopy is remarkable. I was very surprised and pleased that many young scientists started again the research on the microscopic piezoelectric effects in various biopolymers. New instruments revealed many interesting results. The size of measurement was centimeters in my days, but now it is nanometers!

Lang:

That is quite a difference. Quite a change! Many orders of magnitude!

Fukada:

But I am not satisfied with present type of PFM. The present type of PFM can measure two kinds of piezoelectric constants, d33 and d31, but not d14, which means the shear piezoelectric effect which is universally present for the biological polymers in nature. The further improvement of the measuring instruments should contribute to the new research.

The elucidation of the mechanism of Wolff’s law, that the direction of the growth of bone is determined by externally applied stress, seems to be the most interesting and important theme of research in the future. The astronauts after staying in space with no gravity lose their weight of bone and muscle. On the contrary, the rehabilitation and exercise increase the bone and muscle. There is a correlation between applied stress and growth of bone and muscle. The piezoelectricity in biopolymers may have some role in this mechanism. And that is my dream in the future research.

And, one more problem that I am interested in is a membrane protein called Prestin. It is located in the outer hair cells of the cochlea of the ear and controls the sense of hearing. The sense of hearing is… The industrial microphone cannot achieve the sensitivity of ear.

Lang:

That’s interesting. That’s important.

Fukada:

Both direct and converse piezoelectric effect have been already observed. The piezoelectric constant reported is extraordinarily large, as 1000 pC/N, the highest value in polymers.

Lang:

That’s higher than in any other material, I think, higher than ceramics, by far.

Fukada:

So, the mechanism of piezoelectricity in Prestin is not well elucidated yet. It seems to involve the displacement of ions accompanied by the conformation change of polypeptide molecules. The origin of piezoelectricity in polypeptides is ascribed to the change of dipolar orientation and the movement of ions is not included. But for this protein, dipolar orientation plus the displacement of ions might be important. And there is already some experimental evidences.

Lang:

That’s very interesting.

Fukada:

Since the sequence of bases of this polymer has been already analyzed, the mass production of and various practical applications can be done. That is my another dream.

Lang:

Are you still engaged in research at present?

Dr. Date published a very ingenious paper in 2000: ‘Electrically controlled elasticity utilizing piezoelectric coupling’ in the Journal of Applied Physics. The elastic modulus of piezoelectric materials such as PVDF and PZT can be increased or decreased by connecting a negative capacitance circuit. This technique is interesting in many problems in acoustics. And we have already made experiments in airborne sound and underwater sound. We have also developed some theory. So I am hoping that I can complete the paper with Dr. Date pretty soon.

Lang:

That would be wonderful.

Fukada:

Thank you.

Lang:

I did a little bit of searching through the literature. Just going back to 1984, you had published 11 papers since 1984, the most recent one in 2012. [Actually 94 papers of which Dr. Fukada was first author on 28.] One was cited 35 times and two others were cited 12 and 14 times. And you also had those two papers in Japanese that were published. So you are really going very, very strong. I think that at age 93 it is utterly fantastic.

Fukada:

Oh, thank you very much.

Lang:

It is a great honor to be able to talk to you.

Fukada:

I am very happy because I was helped by my cooperators.

I had many good teachers, and very good cooperators.

Lang:

Well, I thank you very very much. I think that this has been a fascinating discussion.

Fukada:

I thank you very much for coming from Israel, and this conversation gave me a good part and encouraged me. So I am very grateful to you. Thank you very much.

Lang:

Thank you. It’s been a delightful experience.