A silicon sheath that can completely envelope a rabbit heart is reported in a study published in Nature Communications this week. The elastic multifunctional membrane is capable of measuring various physiological parameters simultaneously across the entire surface of an isolated beating heart, something that has not been possible in the past.
Devices that can measure and map physiological parameters of the heart - such as mechanical strain, temperature or electrical activity - are important tools for basic and clinical cardiac research. Previous sensors had to be glued or sewn to the heart surface and only covered relatively small areas, therefore there were drawbacks regarding practicality and functionality. John Rogers and colleagues use a 3D printer to create an anatomically accurate reproduction of a rabbit heart based on anatomical information obtained from a medical imaging scan. This 3D-printed template heart allowed them to develop their sensors using a complex design so they were precisely located by specific areas on the heart. They could then embed them in a silicon membrane. The resulting form-fitting multifunctional silicon sheath naturally keeps the sensors in place on the heart surface without the need of glue or sutures, but, at the same time, remains sufficiently elastic not to interfere with cardiac pump function. As a proof-of-principle, the team apply their sensor membranes to isolated rabbit hearts in a perfusion chamber and use them in various scenarios, for example to measure heart rhythm, electrical stimulation of the heart, real-time changes in pH during restriction of blood supply in the heart or changes in temperature as a result of localized burns during a procedure known as cardiac ablation.
The flexibility of the design allows, in principal, for the integration of a range of other functionalities that not only allow to measure but could also control heart function. So far, this device has only been used in isolated hearts - for chronic, implanted devices, further developments with regards to power supply, wireless data communication, and device encapsulation must be made.