Programmable micro-transfer-printing for heterogeneous material integration

Micro-transfer printing is an emerging assembly technique to deterministically transfer ink comprising micro-/nano-objects from a donor substrate to a receiver substrate. This technique has generated increasing interest over the last decade due to its unique capability of integrating diverse heterogeneous materials into various structures and layouts. The growing number of applications enabled by micro-transfer printing includes flexible electronics, sensors, photovoltaics, and micro-LED displays. This work presents a micro-transfer printing approach, which relies on thermally induced adhesion modulation of shape memory polymer materials. An individually addressable micro-fabricated resistive heater array is used to locally deliver the heat for transfer pixel actuation. Selectively transferring chips from a closely packed microchip donor array (pitch: 100 µm, size: 50 × 50 µm2) is demonstrated. The transfer head can be dynamically configured to assemble micro-objects in arbitrary patterns, allowing digital manufacturing, object sorting, or in-line assembly correction of defects. These capabilities, together with the simple and robust structure of the transfer head, can enable high process scalability and flexibility for heterogeneous material integration.