A Hydrogel-Based Ultrasonic Backscattering Wireless Biochemical Sensing.

Juhong Nam,Esther Kim,Seung Hyun Song,Albert Kim,Hyunji Shim,Moonchul Park,Eunjeong Byun,Sayemul Islam

doi:10.3389/fbioe.2020.596370

Juhong Nam, Esther Kim + Show 6 more

Open Access

https://doi.org/10.3389/fbioe.2020.596370

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Abstract

Wireless monitoring of the physio-biochemical information is becoming increasingly important for healthcare. In this work, we present a proof-of-concept hydrogel-based wireless biochemical sensing scheme utilizing ultrasound. The sensing system utilizes silica-nanoparticle embedded hydrogel deposited on a thin glass substrate, which presents two prominent interfaces for ultrasonic backscattering (tissue/glass and hydrogel/glass). To overcome the effect of the varying acoustic properties of the intervening biological tissues between the sensor and the external transducer, we implemented a differential mode of ultrasonic back-scattering. Here, we demonstrate a wireless pH measurement with a resolution of 0.2 pH level change and a wireless sensing range around 10 cm in a water tank.

Highlights

Assessments of the analytes in biofluids through biochemical monitoring have been a major goal for healthcare
We demonstrated an ultrasonic hydrogel biochemical sensor system operated in a pulse-echo mode using a prototype pH-sensitive hydrogel sensor
The silica nanoparticle loading is introduced to the hydrogel network to increase the scattering of the propagating ultrasonic waves, which enables the inference of the hydrogel volume from the pressure ratio of the backscattered ultrasonic waves (Equation 5)

Summary

Introduction

Assessments of the analytes in biofluids through biochemical monitoring have been a major goal for healthcare. The swelling/deswelling responses of hydrogels typically do not involve the use of enzymes or catalysts; the lifetime of the hydrogel based systems can be much longer than those involving enzymatic reactions (Hassan et al, 1997; Heo et al, 2011) For these advantages, numerous hydrogel-based systems with many different applications including sensors, electronics, and soft robotics have been reported (Hassan et al, 1997; Qiu and Park, 2001; Lee et al, 2004; Lei et al, 2006; Heo et al, 2011; Song et al, 2014; Cangialosi et al, 2017; Park et al, 2018; Yang and Suo, 2018; Yuk et al, 2019)

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