Noise Characteristics and Particle Detection Limits in Diode$+$MTJ Matrix Elements for Biochip Applications

A fully scalable matrix-based magnetoresistive biochip has been recently introduced for the detection of biomolecular recognition events. This work reports results for a 3times3 cells matrix comprising hydrogenated amorphous silicon diodes (PIN and Schottky) and aluminum oxide magnetic tunnel junctions (MTJ). The noise characteristics of the individual thin film diodes (TFD) and the MTJ were analyzed for measuring frequencies from DC to 1 kHz, allowing the detection of single magnetic nanoparticles with 250 nm and 130 nm diameters. For 50 nm particles, and at 1 kHz, minimum number of detectable labels ranges from 20 (Schottky diodes) to 50 (PIN diodes).