Title :
A Wireless IC for Time-Share Chemical and Electrical Neural Recording
Author :
Roham, Masoud ; Covey, Daniel P. ; Daberkow, David P. ; Ramsson, Eric S. ; Howard, Christopher D. ; Heidenreich, Byron A. ; Garris, Paul A. ; Mohseni, Pedram
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Case Western Reserve Univ., Cleveland, OH, USA
Abstract :
A 1.1-mW 4-channel integrated circuit for wireless time-share monitoring of chemical and electrical neural activity in the brain is described. The chip architecture can be configured to perform neurochemical monitoring using 300-V/s fast-scan cyclic voltammetry (FSCV) and neuroelectrical recording using extracellular electrophysiology. The 5-mm2 IC is fabricated in AMI 0.5 ¿m double-poly triple-metal n-well CMOS process and uses a 76-¿W, third-order, continuous-time, ¿¿ modulator (CT-¿¿M) per channel that achieves an input-referred noise of 56.7 pArms (dc-5 kHz) and 3.5 ¿Vrms (1.1-5 kHz) for chemical and electrical neuromonitoring, respectively. The chip architecture also incorporates monolithic circuitry for generating FSCV and biphasic constant-current stimulus waveforms. The chip has been externally interfaced with carbon-fiber microelectrodes (CFMs) implanted acutely in the caudate-putamen of an anesthetized rat, and enables chemically resolved monitoring of electrically evoked dopamine release and its postsynaptic bioelectrical response at the same recording site. The dopamine limit of detection (LOD) corresponding to a signal-to-rms noise ratio of three is estimated to be 16.7 nM based on the measured noise performance of the device and its sensitivity to dopamine determined empirically via flow injection analysis. This detection limit compares favorably with the amplitude of phasic dopamine transients that varies in the range of 40 nM-1 ¿M.
Keywords :
CMOS integrated circuits; biochemistry; bioelectric phenomena; biomedical electrodes; biomedical electronics; brain; carbon fibres; cellular biophysics; delta-sigma modulation; integrated circuit noise; microelectrodes; neurophysiology; patient monitoring; time-sharing systems; voltammetry (chemical analysis); 4-channel integrated circuit; AMI double-poly triple-metal n-well CMOS process; C; CFM; FSCV; anesthetized rat caudate-putamen; biphasic constant-current stimulus waveforms; brain; carbon-fiber microelectrode; chip architecture; detection limit; electrical neural recording; electrically evoked dopamine release; extracellular electrophysiology; fast-scan cyclic voltammetry; flow injection analysis; frequency 1.1 kHz to 5 kHz; input-referred noise; monolithic circuitry; neural activity monitoring; neurochemical monitoring; neuroelectrical recording; phasic dopamine transients; postsynaptic bioelectrical response; power 1.1 mW; power 76 muW; signal-noise ratio; size 0.5 mum; third-order continuous-time ¿¿ modulator; time-share chemical neural recording; wireless IC; wireless time-share monitoring; Ambient intelligence; CMOS integrated circuits; CMOS process; Chemical processes; Extracellular; Integrated circuit noise; Microelectrodes; Monitoring; Power capacitors; Signal to noise ratio; Delta-sigma modulator; dopamine; fast-scan cyclic voltammetry; neurochemical monitoring; neuroelectrical recording; wireless integrated circuit;
Journal_Title :
Solid-State Circuits, IEEE Journal of
DOI :
10.1109/JSSC.2009.2035549
