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.
IEEE Transactions on Biomedical Engineering
M. Roham, J. M. Halpern, H. B. Martin, H. J. Chiel, and P. Mohseni, ‘Wireless Amperometric Neurochemical Monitoring Using an Integrated Telemetry Circuit’, IEEE Transactions on Biomedical Engineering, vol. 55, no. 11, pp. 2628–2634, Nov. 2008.