An electrode made with a molded Tootsie Roll® and aluminum tubes can help monitor ovulation status and kidney health. Credit: Adapted from ACS Applied Materials & Interfaces 2021, DOI: 10.1021/acsami.1c11306

Single-use diagnostic tests often aren’t practical for health professionals or patients in resource-limited areas, where cost and waste disposal are big concerns. So, researchers reporting in ACS Applied Materials & Interfaces have turned to a surprising material, Tootsie Roll^® candy, to develop an inexpensive and low-waste device. The candy was used as an electrode, the part of the sensor that detects salt and electrolyte levels in saliva, to monitor ovulation status or kidney health. 

Disposable test strips have advanced the speed and

In preliminary tests, the device could measure salt levels that were physiologically relevant for health monitoring in a salt-water solution and artificial saliva. For example, when covered in diluted artificial saliva, the sensor could reliably measure a change in voltage low enough to detect the 10-30% drop in salts that occurs when a person ovulates.

While the maximum salt content in the artificial saliva samples was similar to that of a healthy adult, the researchers used calculations to estimate that conductivities three times higher, which signal a problem with the kidneys, would be within the measurable range of the device.

Although testing with real human samples is still needed, the researchers say that using soft candy as electrodes opens up the possibility for low-waste, inexpensive electrochemical sensors and circuits in the future.

Reference: “Soft Candy as an Electronic Material Suitable for Salivary Conductivity-Based Medical Diagnostics in Resource-Scarce Clinical Settings” by Donghyun Lee and Beelee Chua, 10 September 2021, ACS Applied Materials & Interfaces.DOI: 10.1021/acsami.1c11306

The authors acknowledge funding from the National Research Foundation of Korea.