Osaka Prefecture University

Flexible and Highly Sensitive pH Sensor Using CCD Platform -One Step Closer to Better Health-

LastUpDate: November 13, 2018

The main point of research

  • With a success of fabricating CCD(*1) platform on a thin and soft film, a highly sensitive flexible pH sensor(*2) with four times more sensitivity than the Nernst theoretical limit has been realized.
  • Integrating temperature sensor with CCD-based chemical sensor, real-time tracking of pH in human sweat as well as monitoring skin temperature have been verified. Such easy-to-wear sensors can potentially boost next generation healthcare management.
  • Human-friendly, practical digital health applications enable to optimize individual’s own health trends and help them identify and address personal risk of developing or managing diseases. This research finding can make preventive healthcare more mainstream, promoting more cost-effective medical treatment.

Overview of research

Figure of CCD-type high sensitive flexible pH sensor, imageDr. Kuniharu Takei, Graduate School of Engineering, Osaka Prefecture University, and other members of his research group succeeded in fabricating a CCD platform on a flexible film. Applying charge transfer and accumulation technology (i.e. CCD) enabled to produce highly sensitive flexible pH and temperature sensors. This high sensitive sensor platform may open a door to build a next class of daily healthcare applications.

This CCD-based flexible pH sensor shows high sensitivity of four times higher than that of the traditional sensor based on the Nernst theory. The soft and human-friendly sensors can be worn on a body like a feeling of a bandage. In the future, low concentrate chemicals (glucose, sodium, potassium etc.) in sweat or skin gas can be monitored based on the fundamental technology of the flexible CCD-based chemical sensor developed in this study.

The research has been published in online journal of Nature Electronics.

Article title: A wearable pH sensor with high sensitivity based on a flexible charge-coupled device.


*1 Charge-coupled device (CCD) using charge transfer technique

CCD is based on the charge transfer generated by a capacitive structure between electrode and semiconductor. The electron charge is continuously transferred from the input to output by controlling the potential well. By repeating the transfer cycle, electron charge in the capacitor is accumulated, resulting in large output (high sensitivity). CCD is the device structure to realize this transfer charge continuously.

*2 pH sensor

pH is a scale used to specify the acidity or alkalinity of an aqueous solution, and pH sensor is to measure the level of pH. The most common method of measuring pH is to use an electrochemical pH sensor.

Research Grant

This work was partially supported by KAKENHI grant (JP17H04926), a JST PRESTO grant (JPMJPR17J5) and the TEPCO Memorial Foundation.

Related links


Graduate School of Engineering, Osaka Prefecture University
Dr. Kuniharu Takei

E-mail takei [at] *Please change [at] to @.