Scientists develop biosensor bandage to collect and examine sweat

Researchers have developed a biosensor bandage that can help collect and analyse the body sweat. The bandage developed in conjunction with a smartphone could someday help diagnose diseases.

The research was published in the American Chemical Society.

Like other biofluids, sweat contains a wealth of information about what is going on inside the body. However, collecting the fluid for analysis, usually by dripping or absorbing it from the skin's surface, can be time-consuming and messy.

Compared with other biofluids such as blood, sweat has the potential to be obtained less invasively for diagnostic testing.

Earlier, researchers had developed tools to collect and analyse sweat, such as temporary tattoos or microfluidic devices, but they typically required wires, electronics or sophisticated structures.

Researchers Tailin Xu, Li-Ping Xu, Xueji Zhang and colleagues wanted to make a wearable biosensor resembling a bandage that samples sweat and uses a simple colour-changing assay to quantify various components.

To make their device, the researchers coated a flexible polyester film with a super-hydrophobic silica suspension. They then etched microwells into the silica layer to collect perspiration. At the bottom of the wells, they placed dyes that change colour with pH or concentration of chloride, glucose or calcium.

The team added an adhesive backing and attached the biosensor bandage onto a volunteer's skin. When the person exercised, their perspiration collected in the microwells, and the spots changed colour.

By imaging and analysing the colours with a cell phone, the researchers determined that the sweat pH was 6.5-7.0, with a chloride concentration of about 100 mM and trace amounts of calcium and glucose. The researchers are now working on increasing the sensitivity of the device.