A Switched-Capacitor Front-End for Velocity-Selective ENG Recording

Abstract

Multi-electrode cuffs (MECs) have been proposed as a means for extracting additional information about the velocity and direction of nerve signals from multi-electrode recordings. This paper discusses certain aspects of the implementation of a system for velocity selective recording (VSR) where multiple neural signals are matched and summed to identify excited axon populations in terms of velocity. The approach outlined in the paper involves the replacement of the digital signal processing stages of a standard delay-matched VSR system with analogue switched-capacitor (SC) delay lines which promises significant savings in both size and power consumption. The system specifications are derived and two circuits, each composed of low-noise preamplifiers connecting to a 2nd rank SC gain stage, are evaluated. One of the systems provides a single-ended SC stage whereas the other system is fully differential. Both approaches are shown to provide the low-noise, low-power operation, practically identical channel gains and sample delay range required for VSR. Measured results obtained from chips fabricated in 0.8 μ m CMOS technology are reported.

Vagus nerve stimulation: state of the art of stimulation and recording strategies to address autonomic function neuromodulation

“…Zariffa proposed to localize active pathways in peripheral nerves using the sLORETA method (Zariffa et al, 2009} while Wodlinger used a beamforming approach for the same task (Wodlinger and Durand, 2009). Rieger et al tried to increase the information rate by using a MCC associated with velocity-selective recordings (VSR) (Rieger et al, 2004, Rieger andTaylor, 2013). In VSR, a series of ring electrodes are positioned in the longitudinal direction of the nerve.…”

Velocity Selective Neural Signal Recording Using a Space-Time Electrode Array

“…can be implemented in a DSP processor, FPGA or PC (digital beamforming). Analog delays can also replace the digitally implemented delays [21]. In our view, velocity selective beamforming can play an important role both in neuroscience research as well as in clinical investigations.…”

“…Also (5) implies that the number of sample points in a given velocity band decreases with increasing velocity. This has been referred to as velocity resolution in the current literature [21].…”

“…This term is actually used to create a uniform frequency-velocity response which could not be achieved by the delay and sum beamformer. Although optimal beamformer weights are rigorously determined by (21) to (24), obtaining closed form equations for the beampattern characteristics such as mainlobe width and sidelobe levels is not easily possible as they depend on the actual values of the weights. Once the optimal weights are found these pattern characteristics can be determined by replacing the beamformer weights in (19) and using regular numerical procedures (e.g.…”

A model of electrical impedance tomography implemented in nerve-cuff for neural-prosthetics control

“…Researchers have used nerve cuffs to identify touch force and slip , estimate joint angle (Chan, Lin et al 2012), and as a sensor in closed loop functional electrical stimulation (FES) systems (Haugland and Sinkjaer 1995, Haugland, Lickel et al 1999, Inmann and Haugland 2004. While many researchers have shown it is possible to classify multiple concurrent signals based on the type of sensory information (Raspopovic, Carpaneto et al 2010, Rieger and Taylor 2013, Al-Shueli, Clarke et al 2014, Karimi and Seydnejad 2015, it has not been possible to differentiate more than two concurrent signals of the same type (Raspopovic, Carpaneto et al 2010, Zariffa 2015, which is a major barrier to their use in prosthetic limbs.…”