Wireless Amperometric Neurochemical Monitoring Using an Integrated Telemetry Circuit


Abstract—An integrated circuit for wireless real-time monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting high-resolution amperometric measurements in four settings of the input current. The chip architecture includes a first-order ∆Σ modulator (∆ΣM) and a frequency-shift-keyed (FSK) voltage-controlled oscillator (VCO) operating near 433 MHz. It is fabricated using the AMI 0.5 µm double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. Measured dc current resolutions of ∼250 fA, ∼1.5 pA, ∼4.5 pA, and ∼17 pA were achieved for input currents in the range of ±5, ±37, ±150, and ±600 nA, respectively. The chip has been interfaced with a diamond-coated, quartz-insulated, microneedle, tungsten electrode, and successfully recorded dopamine concentration levels as low as 0.5 µM wirelessly over a transmission distance of ∼0.5 m in flow injection analysis experiments.

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IEEE Transactions on Biomedical Engineering



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