Apr 19 2019
Quite similar to other biofluids, sweat includes a lot of information about what exactly is happening within the body. But, it can be messy and time-intensive to collect the fluid for analysis, typically by dripping or absorbing it from the surface of the skin.
Biosensor bandage before (left) and after (right) sweat secretion. (Image credit: American Chemical Society)
Currently, scientists have created a bandage-like biosensor that not just collects sweat but also analyzes it in conjunction with a smartphone. The device has been described in the Analytical Chemistry journal from ACS and could someday assist in diagnosing diseases.
When compared to other biofluids like blood, sweat can be obtained less invasively for the purposes of diagnostic testing. Scientists have created tools to gather and analyze sweat, for example, microfluidic devices or temporary tattoos, but they usually need electronics, wires, or intricate structures. Tailin Xu, Li-Ping Xu, Xueji Zhang, and teammates intended to develop a wearable biosensor that resembles a bandage for sampling sweat using a simple color-changing assay for the quantification of different components.
The researchers created their device by coating a flexible polyester film with a super-hydrophobic silica suspension. Subsequently, they etched microwells into the silica layer to collect sweat. Dyes that change color with pH or concentration of glucose, chloride, or calcium were placed at the bottom of the wells. An adhesive backing was added and the biosensor bandage was attached onto the skin of a volunteer.
While the person performed exercises, their sweat was collected in the microwells, and the colors of the spots changed. Following imaging and analysis of the colors using a cell phone, the scientists determined that the pH of sweat was 6.5–7.0, with trace amounts of glucose and calcium and a chloride concentration of about 100 mM. Currently, the researchers are making efforts to increase the sensitivity of the device.
The National Natural Science Foundation of China, Beijing Natural Science Foundation, Fundamental Research Funds for Central Universities, National Postdoctoral Innovative Talents Support Program of China, Program for Guangdong Introducing Innovative and Entrepreneurial Teams, and the Shenzhen Fundamental Research Program funded the study.