title: An ultra-sensitive DeltaR/R measurement system for biochemical sensors using piezoresistive micro-cantilevers.
abstract: Piezoresistive micro-cantilevers are interesting bio-sensing tool whose base resistance value (R) changes by a few parts per million (DeltaR) in deflected conditions. Measuring such a small deviation is always being a challenge due to noise. An advanced and reliable DeltaR/R measurement scheme is presented in this paper which can sense resistance changes down to 6 parts per million. The measurement scheme includes the half-bridge connected micro-cantilevers with mismatch compensation, precision op-amp based filters and amplifiers, and a lock-in amplifier based detector. The input actuating sine wave is applied from a function generator and the output dc voltage is displayed on a digital multimeter. The calibration is performed and instrument sensitivity is calculated. An experimental set-up using a probe station is discussed that demonstrates a combined performance of the measurement system and SU8-polysilicon cantilevers. The deflection sensitivity of such polymeric cantilevers is calculated. The system will be highly useful to detect bio-markers such as myoglobin and troponin that are released in blood during or after heart attacks.
authors: Electrical Engineering Department, Indian Institute of Technology Mumbai, India.
authors: Sudip
authors: S
authors: Nag
authors: Nitin S
authors: NS
authors: Kale
authors: V
authors: V
authors: Rao
authors: Dinesh K
authors: DK
authors: Sharma
mesh_terms: D000465:Algorithms; D015415:Biomarkers / Q000378:metabolism; D001698:Biomedical Engineering / Q000379:methods*; D002138:Calibration; D017097:Electric Impedance; D004582:Electronics, Medical; D004594:Electrophysiology; D004867:Equipment Design; D006801:Humans; D055617:Micro-Electrical-Mechanical Systems; D009211:Myoglobin / Q000032:analysis; D052898:Optical Tweezers; D015203:Reproducibility of Results; D014159:Transducers; D014336:Troponin / Q000032:analysis
chemical_list: D015415:Biomarkers; D009211:Myoglobin; D014336:Troponin