Michel Demierre

Detection of a single magnetic microbead using a miniaturized silicon Hall sensor

Using a highly sensitive silicon Hall sensor fabricated in a standard complementary metal-oxide-semiconductor (CMOS) technology, we detect a single magnetic microbead of 2.8 μm in diameter. The miniaturized sensor has an active area of 2.4×2.4 μm 2, a sensitivity of 175 V/AT and a resistance of 8.5 k. Two detection methods, both exploiting the superparamagnetic behavior of the bead, are experimentally tested and their performances are compared. This work opens the way to the fabrication of low cost microsystems for biochemical applications based on the use of dense arrays of silicon Hall sensors and CMOS electronics.

Micro-Hall devices: performance, technologies and applications

In this review paper, we summarize the performance (in particular the magnetic field resolution), micro-fabrication technologies and applications of micrometer sized Hall effect devices. Additionally, our activities in this domain are briefly described.

A Vertical Hall Device in CMOS High-Voltage Technology

In this paper we demonstrate for the first time, how vertical Hall devices manufactured in CMOS technology attain sensitivities comparable to those of conventional silicon plate-shape devices without any additional etching step. This was achieved by taking advantage of the low doping levels of a high-voltage technology. An additional unconventional doping reduction method can further improve the sensitivity. The current related sensitivity of the presented devices varies from 18 V/AT up to 127 V/AT for different sensor geometry and doping concentrations. The linearity error is less than 0.04% for magnetic fields up to 2T.

Integrated Hall sensor array microsystem

A CMOS microsystem consists of an array of miniature integrated Hall sensors and dynamic offset cancellation interface electronics. It has 86 V/Tesla magnetic sensitivity, 160 μTesla magnetic offset field, and 0.8 μTesla/√Hz noise density while consuming 2.3 mA from a single 5 V supply. It measures the Earths magnetic field with 5% precision.