Screen Printed, Skin-compliant Sensors for Mouse Electrocardiography

Advances in flexible electronic materials have seen the emergence of ultra-thin epidermal sensors for monitoring human electrocardiography (ECG), with some designs only micrometers in thickness. Application of this technology to mice could refine current pre-clinical protocols by enabling more humane, non-invasive monitoring systems. This work characterises the electrical properties and skin-conformity of three screen printed Ag/AgCl ECG electrode designs for mice. Specifically, we examine substrates of temporary tattoo paper and 25 μm thick polyester, which attach to the skin using conductive paste or a polyurethane-film (PU). This work demonstrates how skinconforming sensors can collect acceptable quality mouse ECG signals. Whilst electrical characterisation suggests that probes without conductive paste are reliant on capacitive coupling, where interface adhesives and the mouse’s thin stratium corneum act as a dielectric. Finally we examine skin conformity with histological imaging, revealing tattoo substrate and PU to be considerably more compliant than polyester. This opens up discussion into which materials would be most suitable in developing an ECG interface for free-moving mice.