Sensation thresholds in electrocutaneous stimulation

Abstract

Acoustic or visual warning signals for workers in hazardous situations might fail under loud and/or lowvisibility work situations. A warning system should be developed that uses electrocutaneous stimulation through textile electrodes. Previous work investigated suitable stimulation parameters using TENS electrodes. The aim of this study was to compare TENS and textile cuff electrodes in terms of sensation thresholds, qualitative and spatial sensation. A study on 30 healthy volunteers (f=13, m=17) of mean age of 26.7 years was conducted applying bi-phasic rectangular current pulses to electrodes attached to the upper right arm. The study revealed that perception, attention and intolerance thresholds, qualitative and spatial perception are comparable indicating that future studies with the textile cuff electrodes can be generally based on the previous results with TENS electrodes.

A review of textile-based electrodes developed for electrostimulation

“…Excerpts of analyzed electrode designs categorized by production technique; figures reprinted from the respective publication. (I)(a) Ag nano-ink printed electrode on plain weave 61 ; (I)(b) screen-printed electrode array 52 ; (I)(c) screen-printed electrodes integrated into knee orthesis 41 ; (I)(d) poly(3,4-ethylenedioxythiophene) polystyrene sulfonate coating using a polydimethylsiloxane frame 53 ; (I)(e) Ag coated electrodes covered with C-loaded silicone rubber 66 ; (II)(a) Ag/polyamide (PA) embroidered electrodes 40 ; (III)(a) multi-layered circular electrode with Ag fabric and a dual-lock button on the backside 54 ; (III)(b) multi-layered rectangular electrode with Ag/PA fabric on top 50 ; (IV)(a) knitted Ag/PA electrodes integrated in a cuff 35 ; (IV)(b) Ag-AgCl coated PA electrodes integrated into a functional electrical stimulation shirt 21 ; (IV)(c) Ag/PA electrodes integrated into a transcranial electrical stimulation cap 67 ; (IV)(d) flat-knitted Ag/PA electrodes, as presented by Euler et al. 65 …”

“…50 However, it can be assumed that most probably yarns were used, especially for woven fabrics. Further, D€ olker et al 66 mentioned that they used a silver-coated knitted fabric to construct their electrodes. However, information is missing regarding the coating method and coating paste composition.…”

“…Within this, Popovi c-Bijeli c et al 62 and Keller et al 63 developed control systems that could activate selected electrode fields to create 'virtual electrodes' of various shapes and sizes. 20 In recent years, the focus has shifted to the integration of electrodes into electrode garments for FES and TENS, as presented by Curteza et al, 35 Poboroniuc et al, 37 D€ olker et al, 66 Goncu Berk 40 and Liu et al, 41 who manufactured various kinds of electrode sleeves and cuffs to stimulate limb muscles and nerves, whereas Moineau et al 21 and Li et al 54 designed entire electrode shirts or pants, and Hunold et al 67 developed an electrode cap for transcranial electrical stimulation.…”

“…Ten studies (presented in 11 publications) used electrodes in a wet condition with either water, saline solution or gel, 21,35,37,39,50,53,54,60,62,65,67 whereas three studies (presented in four articles) used dry electrodes without additional electrolytes. 41,50,52,66 Yet it must be noted that, although D€ olker et al 66 chose dry electrodes, the skin was moistened with a wet towel before use, making the electrodes a between-state of dry or wet electrodes. In the other studies, no electrolyte was reported.…”

“…Although three studies successfully developed dry textile electrodes that did not exceed users' pain thresholds, 41,50,52,66 most researchers came to the conclusion that wet electrodes are more reliable and the risk for painful sensations is reduced. For example, Zhou et al 50 compared the performance of the same electrode construction in dry and wet conditions.…”