Shape memory polymer dry adhesives and their use for advanced transfer printing enabling soft microsystems

Transfer printing is a method that transfers structures from one substrate to another, allowing for the formation of a homogeneous or heterogeneous integration. A stamp composed of an elastomeric substance, such as PDMS (polydimethylsiloxane), is utilized to pick-up desired structures, referred to as 'inks,' from a donor substrate and print them onto a receiving substrate. Research on the transfer printing technique has been conducted into two branches, one is improving technique such as the yield, alignment accuracy and scaling, and the other is demonstrating its capability for multiple functionalities and diverse fields. Improving the technique of transfer printing hinges on understanding the adhesion between the ink-substrates, ink-stamp, and even between different inks. In general, higher adhesion between ink-stamp than ink-donor substrate is preferred when picking, while higher adhesion between the ink-receiving substrate or ink-ink than ink-stamp is preferred when printing. Researchers have been studying to enhance the transfer printing technique by implementing microstructures, optimizing the speed and pressure, and using PDMS as a stamp material. However, PDMS lacks the ability to actively control its material properties. This dissertation introduces the use of shape memory polymer (SMP) as a stamp for transfer printing. SMPs possess two or more states that can be toggled via external stimuli, such as heat. When the SMP stamp comes into contact with the ink on the donor substrate, the adhesion between the stamp and the ink is increased through van der Waals forces. In contrast to PDMS stamps, SMPs can maintain a flat shape while in contact, preserving their adhesion strength, and recover their shape during the printing stage to release adhesion. The first section of this dissertation also explores the use of SMPs as soft robotic grippers and thin adhesives for flexible adherends like fabric, providing a better understanding of SMPs as adhesives. In the following section, demonstrations of transfer printing using SMPs for single inks with a single stamp and on a large scale with an array of SMP stamps are presented. In order to broaden the potential applications of transfer printing, this dissertation also explores its use in fabricating a variety of soft microsystems. Firstly, a vibrational energy harvester has been created which is capable of scavenging electric current from the electrostatic interaction between the dielectric and the metal electrodes. Secondly, a magnetically actuated microfluidic skin has been developed, allowing for external manipulation of a droplet through the use of a magnetic field. Finally, double-sided electronic devices have been fabricated on ultra-thin substrates, enabling dual functionality by designing different functions on the front and back sides, or by patterning the same design on both sides to double its volume efficiency.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Son, ChangHee

Contributors dc:contributor

• Kim, Seok
• Ferreira, Placid M.
• Feng, Jie
• Shim, Moonsub

• Shape Memory Polymer
• Adhesives
• Transfer Printing
• Soft Microsystems

Statement dc:rights

• Copyright 2023 ChangHee Son

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/120569

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F120569