uniaxially stretching the substrate (right column), all with overlaid FEA predictions. Scale bars, 50 μm. (D) Measured and computed frequency dependence of the inductance and the Q factor of a single 3D toroidal inductor mechanically configured into two different shapes by partial (21%, in an absolute sense, of an original prestrain of 54%; blue) and then complete release of prestrain (red), along with the corresponding 2D precursor (green) as reference. The panels on the right show simulated magnetic field distributions of these structures for feed-in power of 1 W. The arrows indicate direction and their colors indicate magnitude.
The ability to naturally integrate state-of-the-art electronic materials and devices represents an essential, defining characteristic of these approaches. A mechanically tunable inductor based on a 3D toroidal structure with feed and ground lines, all constructed with polyimide encapsulation (1.2 μm) and Ni conducting layers (400 nm), provides an example. Here, the geometry is similar to the “circular helix III” in Fig. 2D, with the addition of contact pads located at the periphery for electrical probing. The graph of Fig. 4D shows measurements and