Microfluidic thread‐based electrode system to detect glucose and acetylthiocholine

Abstract

A reusable and simple to fabricate electrochemical sensor for the detection of glucose and acetylthiocholine using thread‐based electrodes and nylon thread is described. The fabrication of the device consisted of two steps. First, three nylon‐based electrodes (reference, working, and counter) were painted with one layer of conductive inks (silver and carbon ink, or silver/silver chloride ink). The electrodes were taped onto parafilm, and a piece of white nylon thread was wrapped around each electrode connecting the three electrodes. For the glucose system, a PBS solution containing glucose oxidase (GOx) (10 mg/mL), and potassium ferricyanide (K3[Fe(CN)6]) (10 mg/mL) as mediator, was dried onto the thread, and increasing concentrations of glucose (0–15 mM) was added to the thread and measured by cyclic voltammetry (CV). The current output from the glucose oxidation was proportional to the concentration of glucose. For the second system, a solution of acetylcholinesterase (AChE) (0.08 U/mL) in PBS was added to the nylon thread, and increasing concentrations of acetylthiocholine (ATC) (0–9.84 mg/mL) was added and measured by CV. The current output from the oxidation of thiocholine (produced by AChE reacting with ATC) was proportional to the concentrations of ATC added to the thread. From both systems, a graph of current output versus substrate concentration was produced and fitted with a linear regression line that gave R2 values of 0.985 (GOX/glucose) and 0.995 (AChE/ATC).

Thread- and Capillary Tube-Based Electrodes for the Detection of Glucose and Acetylthiocholine

“…Despite the decrease in electrode size and solution volume, the results obtained are comparable to the results obtained in this work. The oxidation and reduction peaks did not experience any notable potential shifts with an increase in concentration, and the potential at which the oxidation peak occurred is consistent with similar work [ 37 , 38 ]. Results obtained for glucose detection using the wax-printed circles platform are comparable to previous work and demonstrate consistent increases in the measured current output proportional to increases in glucose concentration (R 2 = 0.998).…”

“…Compared with earlier work, the detection site of the thread electrodes was significantly smaller in size (cm 2 scale to ~5 mm 2 ) [ 37 , 38 ]. The minimization of the electrode, along with the implementation of microfluidic materials, allowed for a significant decrease in solution volume (from 90 µL in earlier work to 12 µL for the wax-printed circles platform) [ 37 , 38 ]. Despite the decrease in electrode size and solution volume, the results obtained are comparable to the results obtained in this work.…”

“…The sensors consist of a reference electrode, a working electrode, and a counter electrode. The reference electrode, constructed of Ag/AgCl, carries a fixed potential against the electric potential applied to the working electrode, made with carbon ink, when measuring the electron flow from each concentration of analyte [ 38 ]. This effective three-electrode system allows the opportunity to incorporate paper and thread-based materials into fabrication.…”

Recent advances in thread-based microfluidics for diagnostic applications

“…Agustini et al (2016Agustini et al ( , 2017 made some efforts in making low-cost thread-based microfluidic devices for electroanalytical applications, such as a thread based device for micro flow injection analysis based on electrochemical technique. By using thread-based electrodes and nylon thread, Gaines et al (2018b) made another electrochemical sensor to detect glucose and acetylthiocholine. A relative high flow rate of 2.2 µL/s could be achieved.…”

“…More recently, thread substrate has been introduced into microfluidic devices, known as thread-based microfluidics, due to its features such as wide use, high availability, low cost, general hydrophilic nature, as well as the lightweight and easy biodegradability Gaines et al, 2018aGaines et al, , 2018bKabariya and Ramani, 2018;Ochiai et al, 2017;ChuanáYeo and TeckáLim, 2016). Thread-based microfluidic devices utilize threads to construct fluidic channels to perform various analytical assays.…”