Fig. 2: Brain-interfacing functionalities of SMCA.
From: A shape-morphing cortex-adhesive sensor for closed-loop transcranial ultrasound neurostimulation
a, Comparison of the tissue-adhesive strength between Alg and Alg–CA according to stretching direction. Both hydrogel materials were coupled with the SHP substrate. Data points are mean ± standard error of the mean (s.e.m.) (n = 3). Unpaired two-tailed t-test: *P = 0.0417 between Alg/SHP and SMCA groups for tensile adhesive strength, ***P = 0.0009 between Alg/SHP and SMCA groups for shear adhesive strength. b, Shear adhesive strength of the tissue-attached Alg–CA-coated bilayers (coated on PI (grey), PDMS (green) and SHP (SMCA) (blue)) with a backing stiff film (PET). Data points are mean ± s.e.m. (n = 3). One-way analysis of variance test: NS, not significant, indicates P = 0.3370 between the Alg–CA/PDMS and SMCA groups, ***P = 0.0002 between the Alg–CA/PI and SMCA groups. c, Shear stress curves of the tissue-attached Alg/SHP (red), Alg–CA/PDMS (green) and SMCA (blue) films without the backing substrate as a function of tensile strain (elongation rate of 100% min−1). Inset illustration depicts a cross-sectional view of a tissue-attached bilayer patch. d, Normalized plot of shear stress of the tissue-attached Alg–CA/PDMS (green) and SMCA (blue) films as a function of time at an elongation strain of 80%. The inset illustration describes the cross-sectional view of a tissue-attached patch while stretched. e, Comparative images regarding tissue-adhesion performances of Alg/SHP (top), Alg–CA/PDMS (middle), SMCA (bottom) films on bovine brain while shear strain was applied. f, Comparative sequential schematics of the FEA model illustrating the time-variant stress distribution of brain-interfaced PDMS (top) and SMCA (bottom) for 1 h. g, Comparative sequential images of Alg–CA/PDMS (top) and SMCA (bottom) mounted on bovine brain tissue with flexuous cortical morphology illustrating the mechanical behaviour of bilayer films over time. The surface temperature of the brain tissue was set at 37 °C. h, Cross-sectional photographs (top) and corresponding confocal fluorescence images (bottom) of Alg–CA/PDMS (left) and SMCA (right) films mounted on the largely winkled surface of bovine cortex. Each image was obtained 1 h after tissue contact.
