A design for a CMOS frontend integrated circuit （chip） for neural signal acquisition working at wide voltage supply range is presented in this paper. The chip consists of a preamplifier, a serial instrumental amplifier （IA） and a cyclic analog-to-digital converter （CADC）. The capacitive-coupled and capacitive-feedback topology combined with MOS-bipolar pseudo-resistor element is adopted in the preamplifier to create a -3 dB upper cut-off frequency less than 1 Hz without using a ponderous discrete device. A dual-amplifier instrumental amplifier is used to provide a low output impedance interface for ADC as well as to boost the gain. The preamplifier and the serial instrumental amplifier together provide a midband gain of 45.8 dB and have an input-referred noise of 6.7 μVrms integrated from 1 Hz to 5 kHz. The ADC digitizes the amplified signal at 12-bits precision with a highest sampling rate of 130 kS/s. The measured effective number of bits （ENOB） of the ADC is 8.7 bits. The entire circuit draws 165 to 216 μA current from the supply voltage varied from 1.34 to 3.3 V. The prototype chip is fabricated in the 0.18-μm CMOS process and occupies an area of 1.23 mm2 （including pads）. In-vitro recording was successfully carried out by the proposed frontend chip.
A prototype of hybrid neural recording interface has been developed for extracellular neural recording. It consists of a silicon-based plane microelectrode array and a CMOS low noise neural amplifier chip. The neural amplifier chip is designed and implemented in 0.18 μm N-well CMOS 1P6M technology. The area of the neural preamplifier is only 0.042 mm2 with a gain of 48.3 dB. The input equivalent noise is 4.73 btVrms within pass bands of 4 kHz. To avoid cable tethering for high dense mul- tichannel neural recording interface and make it compact, flip-chip bonding is used to integrate the preamplifier chip and the microelectrode together. The hybrid device measures 3 mm×5.5 mm×330μm, which is convenient for implant or in-vivo neu- ral recording. The hybrid device was testified in in-vivo experiment. Neural signals were recorded from hippocampus region of anesthetized Sprague Dawley rats successfully.
HAN JianQiangZHANG XuPEI WeiHuaGUI QiangLIU MingCHEN HongDa
A novel linear microprobe array(LMPA)has been developed by a conventional microfabrication method from silicon.The LMPA leverages the properties of conventional microwire with additional features of naturally formed regular spacing.With the help of periodic microprobe arrays and double-side V-grooves fabricated in advance between each pair of the two microprobes’rear ends,the number of microprobe units for assembly in one array can be flexibly chosen by cleavage fracture from the LMPA.The fabrication method was demonstrated and the prototype device was assessed by electrochemical impedance spectroscopy(EIS)and in vivo test.The SNR of the spikes recorded was 6.
ZHAO Shan ShanPEI Wei HuaZHAO HuiWANG Yi JunCHEN San YuanCHEN Yuan FangZHANG HeGUO Dong MeiGUI QiangCHEN Hong Da
