Wearable health-monitors are everywhere, from Fitbits for the health conscious to continuous glucose monitors for diabetics, but most are limited in what they can tell us, and there are issues around accuracy, calibration and reliability. Researchers in Sweden are working to change that.

The technology, developed by scientists at KTH Royal Institute of Technology in Sweden, employs multi-purpose electrochemical sensors to take measurements of blood and sweat which can be woven into clothes, incorporated into skin-patches or deployed as microneedles, depending on sample requirements. It can also be integrated with existing sensors such as accelerometers and ECG, providing a broad-spectrum overview of important physical parameters.

These multi-purpose sensors differ from much of the current technology, in that they're able to measure a broad range of important biochemical compounds such as sodium, chloride, calcium, magnesium, ammonium, glucose, uric acid, as well as amino acids such as glycine. The sensors are also able to monitor lactic acid buildup during intense exertion.

"Both technology platforms can be used in medical contexts at home or during athletic activity" says Gaston Crespo, Associate Professor in the Division of Applied Physical Chemistry at KTH. "They could also be tools in hospitals and clinics."

One potential medical application is the monitoring of electrolyte balance as well as optimal hydration for patients with kidney disease.

"Kidney problems in particular are associated with the secretion of potassium ions for example and creatinine level in blood, which the technology can identify," says Crespo. "The sensors can also measure how stressed a person is, and their attentiveness."

While the field of wearable health devices has been with us for a while, it's far from mature. Calibration issues abound; the quality and reliability of sampling-cells varies wildly and trustworthy validation of on-body test data are all challenges that need to be faced for the field to advance. In addition, there's the problem for consumers in knowing if they've chosen apps which analyze the data in a reliable – or even useful – way.

The majority of current devices are consumer-based, monitoring basic data during physical activity, but it's the the medical application of wearable sensors that has the greatest potential, and which requires significant advances in sensor accuracy, capability, analysis and reporting.

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