Paul Liu
Department of Electrical Engineering and Computer Sciences, UC Berkeley
BSAC Researcher
November 8, 2011 | 12:00 to 01:00 | 540 Cory Hall, DOP Center Conference Room
Host: Bernhard Boser
The growing need for point-of-care biomedical assays motivates a significant reduction in the size and cost of present technologies. Current solutions use fluorescent or enzymatic labels with complex optical instrumentation that has proven difficult to miniaturize. Recently, magnetic bead labeling has emerged as an alternative solution enabling compact and inexpensive platforms. In this talk, I will present a compact and robust magnetic label detector implemented in 0.18µm CMOS. Hall-effect sensors, electromagnets and readout circuits are integrated on a single 2.5mm x 2.5mm chip. The detection relies on the magnetic relaxation signature of a microbead label for improved tolerance to environmental variations. No external magnet, reference sensor or calibration is required. The sensor offset is suppressed to sub-µV by a mixed-signal feedback loop and correlated double sampling (CDS). Flicker noise and thermal noise are rejected by CDS and averaging. A single 4.5µm bead is detected in 16ms with a probability error of <0.1%.
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