Not everyone is comfortable with being injected for blood samples, which is why scientists have created a ‘smart’ bandage-like plaster that collects sweat in place of blood.

Scientists from China and the US have created a bio-sensing, sweat-collecting smart plaster in order to put an end to all those painful blood tests via injections.

The device consists of an adhesive-backed flexible polyester film that is coated with a super-hydrophobic (water-repelling) silica suspension. Also, four tiny super-hydrophilic (water-attracting) wells with dye are also fitted into the coating.

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When the bandage is attached to a patient’s skin, their sweat gets channeled into those tiny wells, where it is collected. The dyes applied to the bottom of each well consequently change color according to the sweat’s pH level, and its concentrations of chloride, glucose and calcium, as per Telegraph.

A smartphone app and camera are then used to assess the color of the well, giving users with readout of the four parameters. When the device was tested on a volunteer, the app found that their sweat had a pH level of 6.5-7.0, a chloride concentration of about 100nM (nanomolars), and trace amounts of calcium and glucose, wrote New Atlas.

Currently, the bandages fail to give real-time measurements on people’s sweat, but the team is working on advancing the device’s sensitivity, according to the study published in the journal Analytical Chemistry.