Jim Zimmerman and the SQUID

Abstract

The career of Jim Zimmerman, beginning with a solid foundation in electronics and cryogenics, reached a turning point in 1965 when he became coinventor of the rf SQUID (Superconducting Quantum Interference Device), while working a t the Scientific Laboratory of the Ford Motor Company in Dearborn, Michigan. Recognizing the exquisite sensitivity of the SQUID as an amplifier and magnetometer, Zimmerman devoted the remainder of his career, a t Ford and later a t the National Bureau of Standards, t o the further development of the SQUID and its applications. In 1969, Zimmerman also helped found SHE Corporation, which marketed the first commercially successful SQUID. While a t NBS, Zimmerman introduced two variations, the SQUID gradiometer and the fractional-turn SQUID, t o enhance the sensitivity of SQUIDs in special situations. He also developed a n improved understanding of SQUID dynamics by exploring the pendulum analog using carefully made models, work that has benefited a generation of students. Putting the SQUID t o work, Zimmerman investigated applications in metrology, biomagnetism, and geophysics. Notably, he participated in collaborations that recorded the first magnetocardiogram made with a SQUID and the first magnetoencephalogram of an evoked auditory response. Later, Zimmerman explored closed-cycle refrigeration as a means of making SQUIDs more useful outside the laboratory environment, and in 1977 he demonstrated an operating SQUID cooled t o 8.5 K by a Stirling-cycle refrigerator made largely of plastic. Zimmerman is remembered for his keen physical insight, the elegance and simplicity of his experiments, and his willingness t o question conventional wisdom in all aspects of life.

A Review of Fetal ECG Signal Processing Issues and Promising Directions

“…Magnetocardiography [71, 28, 72, 73, 74]; which is a technique to measure the magnetic fields of cardiac signals using extremely sensitive devices such as the Superconducting Quantum Interference Device (SQUID) [75]. …”