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Stretchable, Wireless Sensors and Functional Substrates for Epidermal Characterization of Sweat
Author(s) -
Huang Xian,
Liu Yuhao,
Chen Kaile,
Shin WooJung,
Lu ChingJui,
Kong GilWoo,
Patnaik Dwipayan,
Lee SangHeon,
Cortes Jonathan Fajardo,
Rogers John A.
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201400483
Subject(s) - materials science , sweat , microfluidics , nanotechnology , capacitive sensing , microporous material , inkwell , optoelectronics , computer science , composite material , oceanography , geology , operating system
This paper introduces materials and architectures for ultrathin, stretchable wireless sensors that mount on functional elastomeric substrates for epidermal analysis of biofluids. Measurement of the volume and chemical properties of sweat via dielectric detection and colorimetry demonstrates some capabilities. Here, inductively coupled sensors consisting of LC resonators with capacitive electrodes show systematic responses to sweat collected in microporous substrates. Interrogation occurs through external coils placed in physical proximity to the devices. The substrates allow spontaneous sweat collection through capillary forces, without the need for complex microfluidic handling systems. Furthermore, colorimetric measurement modes are possible in the same system by introducing indicator compounds into the depths of the substrates, for sensing specific components (OH − , H + , Cu + , and Fe 2+ ) in the sweat. The complete devices offer Young's moduli that are similar to skin, thus allowing highly effective and reliable skin integration without external fixtures. Experimental results demonstrate volumetric measurement of sweat with an accuracy of 0.06 μL/mm 2 with good stability and low drift. Colorimetric responses to pH and concentrations of various ions provide capabilities relevant to analysis of sweat. Similar materials and device designs can be used in monitoring other body fluids.