Abstract for NC3Rs symposium

Non-invasive, on-skin sensors are finding many uses for long-term monitoring of vital signs. Their emergence can be attributed to advances in the manufacture of flexible electronic materials which can be integrated into soft substrates that readily interface with the body. There is now a substantial opportunity for ‘reverse translating’ such sensors to interface with animals non-invasively. Preclinical research utilising transgenic mice relies on electrophysiology monitoring, and has been instrumental in advancing our understanding of cardiovascular, muscular, and neurological disorders. However, current monitoring tools for mice are rigid and necessitate invasive surgeries. For example, the gold-standard for electrocardiogram (ECG) collection in free-moving mice requires implantation of a device weighing 20% the animal’s body weight, and demands a 2-week recovery period where the animal is burdened.
This work explores the development of an on-skin device for monitoring mouse ECGs, which would reduce animal burden and enable signal acquisition without invasive surgery. Probes were fabricated by screen printing Ag/AgCl onto thin-film temporary tattoo paper, polyester, or polyurethane (PU). Probe designs were then characterised for their ability to collect ECGs and overcome challenges presented by free-moving mice, such as grooming behaviour and fur regrowth. Our results showed that probes printed on PU and tattoo paper connected capacitively with the body, and could collect ECGs from unconscious mice with a signal-to-noise ratio comparable to an electrode attached using conductive paste. Furthermore, probes printed on PU were able to endure three-days of attachment to free-moving animals whilst still being able to record ECG features.