Ion‐Selective Sensors Based on Laser‐Induced Graphene for Evaluating Human Hydration Levels Using Urine Samples

Abstract

Complex graphene electrode fabrication protocols including conventional chemical vapor deposition and graphene transfer techniques as well as more recent solution‐phase printing and postprint annealing methods have hindered the wide‐scale implementation of electrochemical devices including solid‐state ion‐selective electrodes (ISEs). Herein, a facile graphene ISE fabrication technique that utilizes laser induced graphene (LIG), formed by converting polyimide into graphene by a CO2 laser and functionalization with ammonium ion (NH4+) and potassium ion (K+) ion‐selective membranes, is demonstrated. The electrochemical LIG ISEs exhibit a wide sensing range (0.1 × 10−3–150 × 10−3 m for NH4+ and 0.3 × 10−3–150 × 10−3 m for K+) with high stability (minimal drop in signal after 3 months of storage) across a wide pH range (3.5–9.0). The LIG ISEs are also able to monitor the concentrations of NH4+ and K+ in urine samples (29–51% and 17–61% increase for the younger and older patient; respectively, after dehydration induction), which correlate well with conventional hydration status measurements. Hence, these results demonstrate a facile method to perform in‐field ion sensing and are the first steps in creating a protocol for quantifying hydration levels through urine testing in human subjects.

Process-property correlations in laser-induced graphene electrodes for electrochemical sensing

“…Other groups have modified DLW-created carbon electrodes with copper nanoparticles alone or in combination with diamine oxidase to detect glucose or biogenic amines respectively [ 17 , 18 ]. The group of Claussen has used LIG to make ion-selective electrodes for the detection of ammonium and nitrate in soil [ 19 ] or ammonium and potassium in human urine [ 20 ]. Cardoso et al and Beduk et al reported the successful use of molecularly imprinted polymers (MIP) on LIG electrodes to detect chloramphenicol and bisphenol A, respectively [ 21 , 22 ].…”

Flexible Hybrid Sensor Systems with Feedback Functions

“…[ 78–81 ] Until now, LIG has been applied in versatile flexible sensors to measure strain, [ 82,83 ] pressure, [ 84 ] humidity, [ 85 ] temperature, [ 86 ] sweat biomarkers, [ 87 ] and urine. [ 88 ] Representative research has focused on employing LIG for voice recognition, [ 89 ] human sweat analysis, [ 77,90 ] and gas sensing. [ 76,91 ] For instance, Tao et al.…”

Pattern Directive Sensing Selectivity of Graphene for Wearable Multifunctional Sensors via Femtosecond Laser Fabrication

“…[ 1–4 ] It has been developed to be the core materials of flexible electronics, such as radio frequency identification device (RFID), flexible circuit, transparent electrode, and especially wearable sensors. [ 5–8 ] The graphene‐based sensors have been researched widely in recent years, including strain sensors, [ 9–15 ] gas sensors, [ 16–18 ] chemical sensors, [ 19–21 ] and biological sensors, [ 22–24 ] etc. Wherein, graphene‐based strain sensor is the most popular with the researchers, owing to its high sensibility to tactile.…”

“…Additionally, the graphene or graphene oxide has been applied to detect dopamine, glucose, deoxyribonucleic acid, heavy metal ions, toxic chemicals, and so forth. [ 22–24 ]…”

“…The main reason is that the raw materials and the material processing they reported are uniform and homogeneous. The graphene textiles [ 9–15 ] and graphene/graphene oxide powder or suspension [ 16–24 ] are the popular raw materials for sensors. To improve the sensitivity, a large quantity of active sits and defects should be introduced by weaving, [ 15 ] doping, [ 25 ] oxidating, [ 10 ] and mechanical processing.…”