Wearable sensors have become mainstream for human health monitoring, but what about our friends with fur?

This thought crossed the minds of researchers from the Department of Bioengineering at Imperial College London, who recently unveiled a sensor that can measure vital signs through a thick coat of fur or up to four layers of clothing.

The sensor is composed of either a water or hydrogel silicone composite and acts as an acoustic transducer by harnessing sound waves’ ability to travel through the body — effectively a “watery, squishy stethoscope,” said Yasin Cotur, one of the sensors’ developers, in Imperial’s press release.

The fabrication process ensures that air bubbles are absent in the final system, which could reduce the quality of the data recorded by the microphone encapsulated into the device. The data is wirelessly transmitted to a computer for processing and analysis.  

When the device is integrated into a stretchable, silicone‐based harness and worn over several layers of clothing, it can capture a human subject’s heart rate better than a conventional stethoscope. Similarly, a dog’s heart rate could be monitored easily, although heavy panting can obscure the collection of high-quality data.

External noise in the wearer’s environment reduced the quality of the sound recordings, but the researchers are confident that this can be reduced or corrected through improved soundproofing of the device.

One unique application of the sensor is for working animals like police or military dogs that sniff out bombs, drugs, or other targets. By establishing baseline conditions for heart and breathing rates, a dog’s “sureness” in identifying a target could be gauged.

Along with its low cost and easy fabrication, the device’s noninvasive design circumvents any potential discomfort that might be experienced by wearing a sensor directly on the skin and eliminates the need to shave hair.

“The next step is to validate our system further with animals, primarily focusing on sniffer dogs and then horses and livestock later on,” said Yasin.

Research article available at Y. Cotur, et al. Advanced Functional Materials, 2020, doi/10.1002/adfm.201910288