Thermal Controlled Tunable Adhesive for Deterministic Assembly by Transfer Printing

Abstract

Transfer printing techniques based on tunable adhesives that enable heterogeneous integration of materials in desired layouts are essential for developing existing and envisioned systems such as flexible electronics and micro‐LED (µ‐LED) displays. Here, a novel thermal controlled tunable adhesive, which not only has the ability of eliminating the interfacial adhesion for printing but also provides a new strategy for enhancing the interfacial adhesion for pick‐up is reported. The tunable adhesive features cavities filled with air on the surface. This simple construct offers thermal controlled suction and thrust with their amplitudes on the order of a few tens of kPa within 100 °C temperature change, which enables a reliable damage‐free transfer printing. Systematically theoretical and experimental studies reveal the underlying thermal induced pressure change mechanism and provide insights into the design and operation of the thermal controlled tunable adhesive. Demonstrations of this smart adhesive in manipulation of various surfaces and transfer printing of micro‐scale Si inks and µ‐LEDs illustrate its unusual capabilities for deterministic assembly by transfer printing.

Transfer printing based manufacturing process for flexible micro-light emitting diode phototherapy devices

“…Magnetic and electrostatically driven micro-transfer manipulators are advanced form of conventional PDMS structured manipulators with higher adhesion on/off ratio and superior control of adhesion, but additional external stimuli can cause impairments on transferred objects such as micro-LED, which requires further modification and improvement for broader adaptations. Thermally actuated transfer printing have also been proposed by Luo et al 22 in 2021, where hermetically sealed interface between manipulator and device with pressure inside the cavity of manipulator is tuned by temperature. Albeit of advances in transfer printing manipulator tools, more credible and reliable apparatus with expediting operating mechanism in cost-effective manner needs to be developed for wider adaptation of micro-LED in integrated photo-biomodulation or phototherapy purpose.…”

Magnetically Driven Non‐Contact Transfer Printing Based on a Bi‐Stable Elastomeric Stamp

“…As a versatile material assembly technique that enables the heterogeneous integration of a variety of materials in desired 2D or 3D layouts, transfer printing with unique capabilities to transfer inks (e.g., electronic components) from their fabricated substrate (i.e., donor) onto a receiving substrate (i.e., receiver) using an elastomeric stamp is essential for developing adhesion. [59][60][61] Despite the merit of offering an infinite adhesion switchability, this laser-driven non-contact transfer printing technique based on the interfacial thermomechanical mismatch still requires a relatively high temperature of over 200 °C.…”

“…To meet the above stringent requirement, a good attempt is to introduce interfacial thermomechanical mismatch via laser heating to eliminate the interfacial adhesion. [ 59–61 ] Despite the merit of offering an infinite adhesion switchability, this laser‐driven non‐contact transfer printing technique based on the interfacial thermomechanical mismatch still requires a relatively high temperature of over 200 °C. To further reduce the temperature to be within 100 °C, shape memory effect and active surface design [ 62–67 ] of stamp have been explored to improve the reliability of laser‐driven transfer printing process.…”

Challenges in Materials and Devices of Electronic Skin

“…A mechanism is shown in Figure 7c that depicts a laser beam heating inks selectively to facilitate the interface bonding/debonding, completing the patterned layer. 245 Although there are challenges that patterns may be incomplete and the combination of active layers and substrates is not unbreakable, transfer printing is still applicable for a wide range materials and active elements can be distributed over a large area with successive transferring, leading to cost-effective large-area production. 246 Inkjet printing provides a method that no masks and stamps are needed to fabricate E-skin with large scales and low cost, as well as high resolution.…”

“…256 However, a 3D printer usually has one nozzle that can not print multiple materials at the same time, 243 (c) Realizing transfer printing based on laser-assisted temperature control that high temperature promotes adhesion elimination while low temperature promotes adhesion enhancement. 245 (d) Schematic of inkjet printing of nanoparticle suspension inks. 248 (e) Asymmetric microsupercapacitor fabricated by inkjet printing.…”