Figure 2: Properties of a tunable adhesive gel.
From: A strain-absorbing design for tissue–machine interfaces using a tunable adhesive gel

(a) Photograph of a large piece of a gel sheet (8 × 8 cm, 1 mm thick) in contact with a hand and supporting a coin (5 g). (b) Adhesive gel, which consists of polyrotaxane, photoinitiator and poly(vinyl alcohol). (c) Typical stress–strain curves of the gels containing different concentrations of PVA, and the shape of the strips used for the measurements (inset). (d) Average Young’s moduli and standard deviation from five samples (error bar) of the gels containing PVA in different concentrations. (e) Average values of the shear stress and peel-off force required to slide (or delaminate) the Au film on the gel and the standard deviation from nine samples (error bar) of values corresponding to nine samples each of the different gels (Inset represents adhesion force measurement setup for lateral direction, top left, and perpendicular direction, bottom right). (f) Resistance and capacitance values of the rotaxane gel and the 5 wt% PVA gel as functions of the frequency, which ranged from 20 to 106 Hz (dashed line represents the capacitance).