Fig. 5: Ultrasoft devices for bio-interfaced applications with suppressed immune responses and mechanical compatibility with living tissues.

a–c Images of Masson’s trichrome staining for immune responses to three types of model devices after 4-week subcutaneous implantation in mice: an ultrasoft device with a soft interlayer (i.e., SEBS/hydrogel bilayer with the thicknesses of 1.2 μm and 200 μm, respectively), a SEBS device, and a hydrogel device (both in the thickness of 200 μm for the latter two). Implants labeled with #; scale bar, 200 μm. d Measured scar tissue thicknesses from the Masson’s Trichrome staining images for the three cases. Data for scar tissue thickness are represented as mean values ± standard deviation (s.d.) from five samples, and the corresponding data points are overlaid. (statistical significance was analyzed via two-tailed T test, ***P = 0.00032; n.s., not significant). e Schematics showing an ultrasoft EP-record device attached to a rat heart for measuring ECG signals. f Pictures showing an ultrasoft device wrapping on a beating heart without visible location shift during a period of 5 minutes recording (top). In comparison, an EP device built on a SEBS substrate is observed with some rotation and upward shifting (bottom) (scale bar, 5 mm). g ECG signals recorded by an ultrasoft device (top) and a conventional SEBS device (bottom). The maintained recording location of the ultrasoft device on the heart is also reflected by the consistency of the signal features across the 5-min period, which is very different that those from the conventional device. h Left ventricle pressure (LVP) recorded when the devices are wrapped on the heart: stable LVP is maintained before and after mounting the ultrasoft device (top), whereas a conventional device with higher mechanical constraint to the heart beating induced an obvious increase in the LVP amplitude (bottom).