Carbon Nanotube-Based Ion-Sensitive Field-Effect Transistors with an On-Chip Reference Electrode Toward Wearable Sodium Sensing

Abstract

Ion-sensitive field-effect transistors (ISFETs) are a promising platform for real-time, continuous monitoring of sodium ions in human sweat. However, realization of true wearable sensors is restricted owing to bulky reference electrodes. Herein, we demonstrate carbon nanotube (CNT)-based ISFETs with an onchip reference electrode suitable for wearable sodium detection. An Ag/AgCl ink and a polyvinyl butyral membrane are utilized to fabricate the integrated reference electrode with a compact size. The CNT surface is functionalized with a polyvinyl chloride-based sodium-selective membrane composed of a specific ionophore to capture sodium ions. The sodium sensor shows the sensitive detection of sodium ions in a range from 0.1 to 100 mM, which covers human sweat sodium concentrations and good selectivity for interfering ions existing in sweat such as potassium, calcium, and magnesium ions. The miniaturized reference electrode can provide a stable potential comparable to that of a commercial reference electrode. The sensor has the ability to selectively detect the sodium ions in artificial sweat.

Environment-friendly degradable zinc-ion battery based on guar gum-cellulose aerogel electrolyte

“…With the gradual progress of science and technology and the continuous development of society, an increasing number of problems are faced by human beings. Various types of electronic devices are developing rapidly, such as lithium-ion batteries, 1–3 sodium-ion batteries, 4,5 zinc-ion batteries 6–8 and supercapacitors. 9,10 However, they are usually built using nondegradable materials that exist stably in the environment.…”

High‐Performance Bioelectronic Circuits Integrated on Biodegradable and Compostable Substrates with Fully Printed Mask‐Less Organic Electrochemical Transistors

“…The performance of current‐driven OECTs printed on biodegradable and compostable substrate are benchmarked with several ion‐sensitive transistor technologies in Table 2 showing that our printed OECT ion sensors outperforms silicon, [ 67 ] metal‐oxide, [ 68 ] carbon nanotubes, [ 69 ] graphene, [ 70 ] electrolyte‐gated organic field‐effect transistors, [ 71 ] and OECTs. [ 20,21,63,72–74 ] Moreover, we note that the majority of state‐of‐art approaches [ 20,21,60,67–70,72,74 ] use silicon or glass substrates and photolithography that, because of wet processing and chemical etching, is not ideally suited for biodegradable and compostable substrates.…”

Applications of Carbon Nanotubes in the Internet of Things Era

“…The CNT materials have shown efficient therapy in musculoskeletal tumors [67], restoration of neural activity [68], engineering vascularized oriented tissues [69], and treatment of cancer [70,71] as well as artificial joint materials [72]. Besides, CNT transistor-based sensors provide early diagnosis by acquiring the sodium concentration of sweat [73] and respiration gases [74]. The electronic skin based on piezoelectronics and synaptic transistor [75] provides promising intelligent prosthetics [76].…”