A New Method of Temperature Drift Compensation for Highly Sensitive Magnetoresistive Biochips

New bio-detection methods based on giant magnetoresistance (GMR) or tunneling magnetoresis-tance (TMR) sensors and magnetic nanoparticles are attracting much attention due to their high sensitivity and low cost. In literature, signal to noise ratio (SNR) is often used to estimate detection limit. However, because the actual bio-signal is obtained by differentiating signals before and after biological reactions, large temperature coefficient (>1000PPM/degC) of these devices can result into significant temperature drifts during the biological reaction, which may limit the resolution of the system. This will further degrade when considering the integration of biosensors and integrated circuit (IC) since analog components are also exposed to chemical solutions and contribute to drift. In this paper, a drift free detection scheme called "Double Modulation-Dual Bias" (DMDB) method is proposed as a solution to this issue.