New plasma Hall effect magnetic sensors: macrosensors versus microsensors

Abstract

This paper is the first attempt to use the plasma Hall effect for magnetic field detection. The plasma Hall sensor measures the Hall voltage induced by ac electrons plasma in the magnetic field. In a theoretical analysis, we develop an analytical model of the plasma Hall sensor in order to express the plasma Hall voltage as a function of electrode geometry, magnetic field, plasma discharge field, and fluid pressure. On these bases, we have designed, fabricated, and characterized the neon plasma Hall sensors in the macroscale as well as those in the microscale. The plasma Hall macrosensor, using steel wire electrodes in a low-pressure chamber, shows a magnetic field sensitivity of 136.7 +/- 10.1 mV/G with 8.43% nonlinearity at a neon pressure of 80 +/- 5 Torr for a circuit gain of 15.56. The macrosensor, however, shows long-term instability due to the neon pressure instability in the vacuum chamber, which motivates the research on the plasma Hall microsensor. The plasma Hall microsensors using the electroplated copper electrodes in on-chip vacuum package show a magnetic field sensitivity of 8.87 +/- 0.18 mV/G with 4.48% nonlinearity at a neon pressure of 7 +/- 1 Torr for a circuit gain of 5.5. The microsensor shows good stability for 12 h. Fundamental characteristics of the macrosensors and microsensors are compared and discussed, thus verifying the feasibility of the plasma Hall sensor for a new class of magnetic microsensor. (C) 2001 Elsevier Science B.V. All rights reserved.