Editors' ChoiceBiosensors

Mass-producing wearable sensors: No sweat

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Science Translational Medicine  11 Dec 2019:
Vol. 11, Issue 522, eaaz9766
DOI: 10.1126/scitranslmed.aaz9766


Laser engraving can mass-produce cost-efficient, wearable sensors that monitor vital signs and sweat, detecting biomarkers linked to chronic diseases.

Wearable sensors can enhance the management of chronic diseases. Attached to the patient’s body, wearable sensors enable real-time, noninvasive monitoring of the body’s biological processes. Vital signs, including heart rate and body temperature, can be measured. Particularly useful is the monitoring of sweat, which contains biomarkers associated with chronic diseases. However, wearable sensors can be expensive to manufacture: To enable precise measurements, the production of wearable sensors often requires expensive equipment, long processing time, and extensive personnel training, which elevate costs.

Yang and coauthors created a cost-efficient method to mass-produce wearable sensors. Instead of using semiconductor-based technology that is commonly used to produce components for wearable sensors, the authors used a laser to directly convert a plastic sheet into a multifunctional wearable sensor, which could simultaneously measure respiration or heart rate, body temperature, and biomarkers from sweat. Resembling inkjet printing, the laser beam was driven by a precision motor to scan the plastic sheet following a microscopic pattern. Along this micropattern, the laser energy was adjusted to convert the plastic either into microchannels, which guided sweat, or into graphene, a form of carbon that changes electric properties in the presence of biomolecules from the sweat. The graphene elements also produced electric signals in response to forces or temperature change, which enabled the measurement of heart and respiration rates and body temperature. The laser-patterned plastics were used as disposable sensors applied to human subjects and were connected to a thumb-size microcontroller, which wirelessly transferred the sensor signals to a smartphone. On the smartphone, sweat-based signals were analyzed to quantify concentrations of uric acid and tyrosine, which are biomarkers for cardiovascular diseases, diabetes, gout, and liver function.

This simple yet revolutionary method of laser engraving can enable a cost-efficient and roll-to-roll production of wearable sensors. Although it may take several years to industrialize such new technology, this invention could potentially benefit individuals that suffer from chronic diseases, especially people in low-resource environments.

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