A bidirectional interface for neural recording and stimulation is proposed. The recording circuitry eliminates the outband interferences thanks to a high selective band pass filter in the 1:1kHz-2kHz band, providing a gain of 24dB. Further amplification is obtained by means of a programmable gain amplifier that can bring the gain to 44dB. The signal is then digitalized with a 16 bit ADC and sent to a microcontroller. In order to minimize the input referred noise, the whole signal acquisition chain has been designed with a Fully Differential approach, by this way an IRN of 364nV has been achieved. Stimulation signals are biphasic current pulses with programmable duration, frequency and amplitude. These patterns are generated by a DAC followed by a Voltage to Current converter. The programmability of the pulse parameters is guaranteed by the microcontroller: the current amplitude can range from 5μA to 20μA, the pulse duration varies from 50μs to 150μs while the frequency can cover from 10Hz to 400Hz. The system has been implemented in a PCB and successfully tested with a pre-recorded neural signal extracted by the peripheral nervous system of a rabbit with a tfLIFE electrode.
A PCB system implementation for neural signals recording and PNS stimulation
LOI, DANIELA;CARBONI, CATERINA;BARBARO, MASSIMO
2010-01-01
Abstract
A bidirectional interface for neural recording and stimulation is proposed. The recording circuitry eliminates the outband interferences thanks to a high selective band pass filter in the 1:1kHz-2kHz band, providing a gain of 24dB. Further amplification is obtained by means of a programmable gain amplifier that can bring the gain to 44dB. The signal is then digitalized with a 16 bit ADC and sent to a microcontroller. In order to minimize the input referred noise, the whole signal acquisition chain has been designed with a Fully Differential approach, by this way an IRN of 364nV has been achieved. Stimulation signals are biphasic current pulses with programmable duration, frequency and amplitude. These patterns are generated by a DAC followed by a Voltage to Current converter. The programmability of the pulse parameters is guaranteed by the microcontroller: the current amplitude can range from 5μA to 20μA, the pulse duration varies from 50μs to 150μs while the frequency can cover from 10Hz to 400Hz. The system has been implemented in a PCB and successfully tested with a pre-recorded neural signal extracted by the peripheral nervous system of a rabbit with a tfLIFE electrode.
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