Figure 4: Biaxial stretching on a soft diaphragm.
(a,b) Biaxially stretchable Co/Cu second maximum GMR sensor on a VHB membrane spanned over a plastic tray to create a sealed chamber. Water is pumped through the inlet to inflate the VHB membrane and stretch the sensor along both lateral directions. A permanent magnet was fixed inside the water chamber, to enable the dynamic detection of diaphragm inflation/deflation cycles. The flat and fully inflated states are shown in the left and right inset, respectively. (c) GMR curves recorded for different areal strains, as stated in the legend. The left and right insets show the biaxially wrinkled sensor at 0% and 175% strain. (d) GMR magnitude (red dots) and sensor resistance (black squares) as a function of applied areal strain. The strain was estimated from side-view photographs of each inflated state (Supplementary Fig. 11). (e) Sensor signal for a pulsating diaphragm for the dynamic magnetic detection of its inflation/deflation (see Supplementary Movie 6). The dashed line is a smoothed graph to guide the eye.
