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Surface-Treated Nanofibers as High Current Yielding Breath Humidity Sensors for Wearable Electronics

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journal contribution
posted on 04.06.2019, 00:00 by Sathvik Ajay Iyengar, Pillalamarri Srikrishnarka, Sourav Kanti Jana, Md Rabiul Islam, Tripti Ahuja, Jyoti Sarita Mohanty, Thalappil Pradeep
As wearable electronics have gained momentum in the past few years, there is a dire need for smart, responsive, and, most importantly, affordable sensors for biological monitoring. One such noninvasive method to gauge body metabolism is via breath analysis. In a successful attempt to sense and record relative humidity levels (%RH) in nasal and oral breath, this work presents an economical route to fabricate a wearable humidity sensor with high sensitivity and a response time of ∼1 s. The sensor consists of a flexible backbone of electrospun poly­(vinylidene fluoride)/reduced graphene oxide (PVDF/rGO) nanofibers which have been selectively sensitized to humidity via surface polymerization of aniline using the inexpensive successive ionic layer adsorption and reaction (SILAR) technique. We report a high sensitivity and a full response range (0–95% RH) supported by a low working voltage and minimalistic circuitry as an attractive feature for integration into wearable electronics. Moreover, as the device sensitivity is adequate even up to 95% RH, it is conducive to detect nasal breath and saturated humidity conditions accurately. As the method utilizes electrospinning, this work involves the preparation of such humidity sensors on a large scale (up to 400 units using 8 mg of rGO) with the benefit of having affordable and cost-effective devices.