Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems, such as flexible electronics and micro LED displays. Here, we report a robust design of a thermal actuated switchable dry adhesive, which features a stiff sphere embedded in a thermally responsive shape memory polymer (SMP) substrate and encapsulated by an elastomeric membrane. This construct bypasses the unfavorable micro- and nano-fabrication processes and yields an adhesion switchability of over 1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere. Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive. Demonstrations of this concept in stamps for transfer printing of fragile objects, such as silicon wafers, silicon chips, and inorganic micro-LED chips, onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications, such as flexible electronics manufacturing and deterministic assembly.

Ultraflexible neural probe is an ideal tool for brain research, which can reduce the mechanical interfacial mismatch between electrodes and brain tissue and can thus reduce the tissue's inflammation and extend the electrodes' service life. However, the low stiffness of ultraflexible neural probe makes it susceptible to bending and buckling during insertion into brain. Here, a simple yet robust design of removable insertion shuttle consisting of a steel needle with a dissolvable spheroid micropost is reported for ultraflexible neural probe implantation. The dissolvable spheroid micropost of insertion shuttle is fabricated by the simple dip‐coating process based on the competition and balance between the surface tension and gravity. A temporary engaging mechanism enabled by the micropost engaged into the via hole on the tip of ultraflexible neural probe is adopted to enable an easy and quick implantation. Experimental studies reveal the fundamental aspects of the design of removable insertion shuttle and the operation of implantation. In vivo implantation of ultraflexible neural probes into rat's brain illustrates the unusual capabilities of removable insertion shuttle with the accurate positioning of probe at desired depth and the stable chronic brain electrophysiological recording, which show great potential in both basic neuroscience and clinical applications.

Surface wrinkling of an elastic graded layer is studied theoretically, numerically and experimentally.

Exiting strategies for 3D shape-changing structures are constrained by either the complicated fabrication process or the harsh demands of active materials. Facile preparation of 3D shape-changing structures with an extremely simple approach based on the elastomeric polymer still remains a challenging topic. Here, we report a fast digital patterning of surface topography of a single-layer elastomeric polymer toward 3D shape-changing structures. The surface topography features digitally engraved grooves by a laser engraver on a poly(dimethylsiloxane) (PDMS) sheet, which is surface oxidized by the UV-ozone treatment. The resulting engraved PDMS sheets exhibit programmable shape-changing behaviors to form various 3D structures under the action of organic solvent. Experimental and numerical studies reveal the fundamental aspects of surface topography-guided 3D shape-changing structures. Demonstrations of this concept in developing various complex 3D shape-changing structures illustrate the simplicity and effectiveness of our approach, thereby creating engineering opportunities in a wide range of applications such as actuators and soft robots.