A Wireless IC for Wide-Range Neurochemical Monitoring Using Amperometry and Fast-Scan Cyclic Voltammetry

An integrated circuit for real-time wireless monitoring of neurochemical activity in the central nervous system (CNS) is described. The chip is capable of conducting measurements in both fast-scan cyclic voltammetry (FSCV) and amperometry modes for a wide input current range. The chip architecture employs a second-order sigma-delta analog-to-digital converter (SigmaDelta ADC) and a frequency-shift-keyed (FSK) voltage-controlled oscillator (VCO) operating near 433MHz. It is fabricated using the AMI 0.5mum double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. In our preliminary measurements, a current resolution of 12pA at a sampling rate of 100Hz and 81pA at a sampling rate of 5kHz is achieved in amperometry and 150-V/s FSCV modes, respectively, for any input current in the range of plusmn430nA. The ADC core and the VCO consume 22muA and 400muA from a 2.6-V power supply, respectively.