A low-cost flexible pH sensor array for wound assessment

Abstract

The pH level in a chronic wound bed is a key indicative parameter for assessment of the healing progress. Due to their fragility and inability to measure multiple wound regions simultaneously, commercial glass microelectrodes are not well-suited for spatial mapping of the wound pH. To address this issue, we present an inexpensive flexible array of pH sensors fabricated on a polymer-coated commercial paper (palette paper). Each sensor consists of two screen-printed electrodes, an Ag/AgCl reference electrode and a carbon electrode coated with a conductive proton-selective polymeric (polyaniline, PANI) membrane. Laser-machining is used to create a self-aligned passivation layer with access holes that is bonded over the sensing and reference electrodes by lamination technology. Characterization of the pH sensors reveal a linear (r 2 = 0.9734) relationship between the output voltage and pH in the 4-10 pH range with an average sensitivity of −50 mV/pH. The sensors feature a rise and fall time of 12 and 36 s for a pH swing of 8-6-8. The sensor biocompatibility is confirmed with HaCaT immortal human kertinocyte cells.

Flexible Substrate-Based Devices for Point-of-Care Diagnostics

“…This wearable potentiometric sensor exhibited a Nernstian behavior to pH ranging from 5.5–8 with good reproducibility against mechanical stress. In another report, a flexible pH electrochemical sensor array was developed on polyaniline, and it showed a linear dynamic range of pH from 4–10 [57]. Recently, a flexible hydrogel fiber-based dressing has been developed for monitoring pH during wound healing [58].…”

A toolkit of thread-based microfluidics, sensors, and electronics for 3D tissue embedding for medical diagnostics

“…The biocompatibility of the carbon/PANI, silver/silver chloride, and nafion utilized for the fabrication of chemical sensors has already been demonstrated in prior work 37 . Physical sensors were covered with layers of PDMS, which is a well-known biocompatible material.…”

An Intelligent Air Quality Sensing System for Open-Skin Wound Monitoring

“…Their proposed approach facilitated a smart bandage preparation, which helped to observe wound healing. Rahim Rahimi [12] proposed a wound assessment approach based on a pH sensor array. The work discussed how the pH level is a key indicator for the assessment of wound healing in a chronic wound bed; therefore, an approach for the measurement of pH level by a low cost pH sensor array was presented, which was placed on palette paper.…”

“…The matrix value showing the total predicted "favourable" classes was 89, out of which one class was truly unfavourable and wrongly predicted to be favourable, while the total unfavourable classes were 145, out of which 116 were predicted correctly, and 29 were truly favourable, but predicted to be unfavourable. By the given confusion matrix of the accuracy and error rate for both classes, prediction could be measured with the help of the formulae given in Equations (12) and (13).…”

“…IoT provides more flexible and low-cost solutions for daily life problems, which ultimately improve the user's life [4,5]. Although many previous researchers proposed air quality sensing systems by using different sensor combinations [6][7][8][9][10][11][12][13], as shown in Table 1, with the detailed description of previous studies provided, we may conclude that there are three reasons for the motivation to design an efficient wound monitoring system.…”