An integrated interface for peripheral neural system recording and stimulation: system design, electrical tests and in-vivo results

Abstract

The prototype of an electronic bi-directional interface between the Peripheral Nervous System (PNS) and a neuro-controlled hand prosthesis is presented. The system is composed of 2 integrated circuits: a standard CMOS device for neural recording and a HVCMOS device for neural stimulation. The integrated circuits have been realized in 2 different 0.35μ m CMOS processes available from ams. The complete system incorporates 8 channels each including the analog front-end, the A/D conversion, based on a sigma delta architecture and a programmable stimulation module implemented as a 5-bit current DAC; two voltage boosters supply the output stimulation stage with a programmable voltage scalable up to 17V. Successful in-vivo experiments with rats having a TIME electrode implanted in the sciatic nerve were carried out, showing the capability of recording neural signals in the tens of microvolts, with a global noise of 7μ V r m s , and to selectively elicit the tibial and plantar muscles using different active sites of the electrode.

Systematic analysis of wavelet denoising methods for neural signal processing

“…The signals were recorded with respect to an external ground placed 1 cm proximally from the intraneural electrode. Data was acquired using a custom neural signal acquisition module featuring eight channels, each one implementing a low-noise front-end and an analogto-digital converter (ADC) [56,57]. The input stage provides a gain of 43 dB with an input-referred noise of 2.97 µV rms in the bandwidth between 1.67 mHz and 8 kHz, taking into account the whole signal path including the ADC.…”

Broadband Prosthetic Interfaces: Combining Nerve Transfers and Implantable Multichannel EMG Technology to Decode Spinal Motor Neuron Activity

“…Despite these challenges, we believe the proposed scheme is more promising than current alternative research pathways. For example, an alternative approach is the direct recording from efferent fibers in peripheral nerves (Micera et al, 2011; Carboni et al, 2016; Ng et al, 2016), which however presents problems related to low signal amplitude and signal-to-noise ratio, small number of identified spike patterns, and potential intraneural damage (Navarro et al, 2005; Carboni et al, 2016). In comparison, the presented strategy may provide a safer and more robust method to operate modern prostheses with functions closer to the biological ones.…”

An HFAC block-capable and module-extendable 4-channel stimulator for acute neurophysiology

“…In addition to this, precise control of stimulation timing and DC leakage is required in order to prevent any damage to nerves resulting from bringing the polarization voltage of electrodes outside of the water window [23][24][25] during application of block. For stimulators that provide enough compliance voltage [2,7,26,27], other limitations can include low output DAC resolution or full-scale output current which will limit the ability of the user to carry out standard nerve function tests such as stimulation strength-duration curves, or reach block thresholds in typical targets such as the rat sciatic or vagus nerves. Many stimulators designed as single chips for implantable systems are further limited by maximum pulse width [26,28] which can limit the frequencies of block used or the method used to deliver conventional stimulation, which may rely on longer pulse widths [29].…”

“…For stimulators that provide enough compliance voltage [2,7,26,27], other limitations can include low output DAC resolution or full-scale output current which will limit the ability of the user to carry out standard nerve function tests such as stimulation strength-duration curves, or reach block thresholds in typical targets such as the rat sciatic or vagus nerves. Many stimulators designed as single chips for implantable systems are further limited by maximum pulse width [26,28] which can limit the frequencies of block used or the method used to deliver conventional stimulation, which may rely on longer pulse widths [29]. An older design such as the Neurodyne [30] could be an excellent and affordable HFAC block stimulator due to its high output current and compliance but is limited by the dynamics of its transformer core when long low-amplitude pulses are required for conventional stimulation.…”