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FLEXIBLE ELECTRONICS

Wearable pH sensing beyond the Nernst limit

Nature Electronics volume 1, pages 580–581 (2018)Cite this article

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A flexible charge-coupled device can be used to create a sensor capable of measuring the pH of a person’s sweat with high sensitivity.

The fluids in our bodies contain chemicals that could be used to reveal the condition of our health. For many years, researchers have tried to extract and decode pieces of information from these fluids, be it blood, saliva or urine. However, the extraction process can be painful, or sometimes inconvenient and embarrassing. In recent years, wearable devices (or wearables) have become increasingly popular and have been used to monitor physical parameters such as heart rate. Some researchers have thus started to consider whether wearables might be of use in the analysis of sweat1,2,3,4,5 — a fluid that can be easily obtained. There are, indeed, numerous chemicals in sweat that can act as indicators of physical and health conditions, from those that can monitor athletic performance to those that can diagnose lung diseases1,2. To detect these chemicals, wearable electrochemical sensors have been developed. Some of these electrochemical sensors can achieve high accuracy and stability, but the sensitivity is usually limited. For example, the sensitivity of pH sensors is usually around 59 mV pH–1, a limit defined by the Nernst equation6, which relates the reduction potential of an electrochemical reaction to the concentrations of chemical species undergoing the reaction. With a limited sensitivity, fluctuations in the sensor reading from external interference can cause errors and inaccuracies in measurements. Writing in Nature Electronics, Kuniharu Takei and colleagues7 now report a flexible and compact pH sensing device that breaks the sensitivity limit imposed by Nernst theory.

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Fig. 1: A wearable charge-coupled device for monitoring the pH of sweat.

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Authors and Affiliations

  1. Department of Medical Engineering, California Institute of Technology, Pasadena, CA, USA

    Yiran Yang & Wei Gao

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  1. Yiran Yang
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  2. Wei Gao
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Correspondence to Wei Gao.

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Yang, Y., Gao, W. Wearable pH sensing beyond the Nernst limit. Nat Electron 1, 580–581 (2018). https://doi.org/10.1038/s41928-018-0166-1

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