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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 CO2laser 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 × 10−3mfor NH4+and 0.3 × 10−3–150 × 10−3mfor 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.
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Wearable Organic Electrochemical Transistor Patch for Multiplexed Sensing of Calcium and Ammonium Ions from Human Perspiration
Abstract Wearable health monitoring has garnered considerable interest from the healthcare industry as an evolutionary alternative to standard practices with the ability to provide rapid, off‐site diagnosis and patient‐monitoring. In particular, sweat‐based wearable biosensors offer a noninvasive route to continuously monitor a variety of biomarkers for a range of physiological conditions. Both the accessibility and wealth of information of sweat make it an ideal target for noninvasive devices that can aid in early diagnosis of disease or to monitor athletic performance. Here, the integration of ammonium (NH4+) and calcium (Ca2+) ion‐selective membranes with a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐based (PEDOT:PSS) organic electrochemical transistor (OECT) for multiplexed sensing of NH4+and Ca2+in sweat with high sensitivity and selectivity is reported for the first time. The presented wearable sweat sensor is designed by combining a flexible and stretchable styrene‐ethylene‐butene‐styrene substrate with a laser‐patterned microcapillary channel array for direct sweat acquisition and delivery to the ion‐selective OECT. The resulting dermal sensor exhibits a wide working range between 0.01 × 10−3and 100 × 10−3m, well within the physiological levels of NH4+and Ca2+in sweat. The integrated devices are successfully implemented with both ex situ measurements and on human subjects with real‐time analysis using a wearable sensor assembly.
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- Award ID(s):
- 1804915
- PAR ID:
- 10458533
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Healthcare Materials
- Volume:
- 8
- Issue:
- 24
- ISSN:
- 2192-2640
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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