Gerhard M. Sessler has helped revolutionize the modern microphone market not once but twice during his career. Dr. Sessler and co-worker James West at Bell Labs invented the first polymer electret condenser microphone in 1962, which provided high performance at a smaller size and lower cost. He discovered that certain polymers could be permanently charged by a number of methods to become stable electrets. When placed between the electrodes of a condenser microphone, the need for external bias was eliminated, resulting in a much simpler, efficient device. The technology was commercialized in 1968 and soon became the world’s dominant microphone, replacing the carbon-button microphone that was used in telephones for 100 years and finding applications wherever microphones are being used. Working with Dietmar Hohm at the Darmstadt University of Technology, Dr. Sessler designed the first microelectromechanical systems (MEMS) condenser microphone based on silicon micromachining in 1983 (the first all-silicon and first one-chip microphone). His lab developed refined micromachining techniques, enabling creation of miniaturized microphones with superior electroacoustics. These microphones were introduced to the market in 2002 and are used mostly in mobile phones but also in laptops, PDA’s, MP-3 players, and hearing aids. At Darmstadt, Dr. Sessler also developed the laser-induced pressure-pulse method for investigating charge and polarization distributions in thin polymer films with micrometer resolution. This has become a leading method for mapping electroactive polymers and polymers used for cable insulation, leading to improved properties of power cables.
An IEEE Life Fellow, Dr. Sessler is currently a professor of electroacoustics with Darmstadt University of Technology, Germany.