Stretchable wearable wireless sensors for physiological monitoring of humans and dogs

Abstract

Despite the significant developments of wearable devices for humans, few devices developed for dogs to monitor the vital signs unobtrusively offer limited comfort and capability. This thesis presents a dog-computer interaction system for remote, real-time and continuous physiological monitoring of dogs. The system consists of a motion sensor for posture detection, an acoustic sensor for recording heart sounds, and a pressure sensor for monitoring breathing activities, all produced using new approaches to render the systems stretchable and flexible.

This thesis detects the posture (lying, sitting, standing and moving) of a dog in real-time with high performance, achieving an accuracy of 86% using a 9-axis inertial measurement unit. This thesis reports a highly flexible, stretchable, and mechanically robust low-cost soft composite material consisting of silicone polymers and water for the recording of heart sounds. When combined with conventional acoustic transducers, the materials reported enables high-performance and real-time monitoring of heart cycles over the furry skin of dogs without the need for direct contact with the skin. This approach enables an entirely new method of fabrication that involves the encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. For monitoring of breathing activities, this thesis reports a simple and cost-effective air-silicone composite transducer which consists of a commercially available gas-pressure sensor combined with an air-enclosed silicone composite. The transducer exploits the motion of the diaphragm due to abdominal geometrical changes during inspiration and expiration.

The developed transducers have been tested both with humans and dogs, primarily focusing on monitoring the heart and breathing separately. This thesis is especially important because it is the first demonstration of stretchable wearable sensors that are suitable for use with furry animals and do not require shaving of the animal for data acquisition. This thesis also presents a custom fabricated complete silicone harness that covers the chest of dogs, in which the transducers and electronics (via silicone box) are embedded. The complete device enables the monitoring of physiological signs of both humans and dogs.