Fig. 6: In vivo validation of a soft robotic thera-gripper for epicardial sensing and electrical stimulation (E-stim).

A Schematic illustration showing the thera-gripper features minimally invasive insertion at the resting state and wraps onto the surface of a beating heart at the actuation state. The thera-gripper contains four strain sensors made of serpentine Au/PI resistors, two E-stim electrodes based on Au, and two temperature sensors made of thermal resistors. B Finite element modeling of the actuation state. The colors in the legend indicate the magnitude of the von Mises stress. C Image of a soft robotic thera-gripper grasping on the epicardial surface of a living mouse heart. Scale bar, 5 mm. D Schematic illustration showing the thera-gripper position on a mouse heart, where the strain sensors (labeled as S1, S2, S3, and S4) are located onto different heart chambers for locally monitoring of dysfunctional tissue. E Confocal microscope images of 3T3-J-2 cells before (control) and after exposure to as-prepared soft robots integrated with an e-skin layer and a PNIPAM hydrogel-muscle layer, incubated at 37 °C and 39 °C for 48 h. Scale bars, 50 μm. F Comparative cell viability before and after soft robot’s exposure, indicating that 3T3-J-2 cells exposed with the soft robot and cultured at the elevated temperature (39 °C) have no decreased viability. Scale bars, 50 μm. Mean ± S.D. n = 3. P value by Unpaired t-test. G Temperature measurements from the thera-gripper during its deployment onto the mouse heart, demonstrate the device’s capability to monitor thermal variations in real-time. H The surface ECG trace during electrical stimulation using a pair of Au E-stim electrodes. Optical images of a healthy heart (I) and an injured heart 2 weeks after myocardial infarction (MI) (J). The MI area is shown by the white dashed circle in (J). M-mode echocardiographic images from a healthy (K) and post-MI heart (L). Representative measurements of local cardiac contractions before (M) and after MI (N) using a soft robotic thera-gripper wrapping onto a living mouse heart.