Sub-microscale Contact Transfer Printing

Background

Over the past two decades, contact transfer printing has evolved into a viable manufacturing technology that can deposit and pattern various organic, polymeric, and inorganic ink materials with micro‐ and nano‐ scale precision, and its inherent amenability to replicate large‐area patterns on flat or curvilinear substrates gives it potential to evolve into a universal platform for parallel deposition of multiple types of materials at the sub‐micrometer length scale. However, the key to enabling such manufacturing is to establish clean and reliable methods for controlling interfacial adhesion and fracture mechanics during ink pickup and release. Interfacial adhesion of elastomers can be affected by their viscoelasticity, stiffness, surface energy, and the geometrical shape and roughness of the interface that forms the contact, as well as the chemical composition and stiffness of the polymeric stamps, but optimization of all of these parameters would require a different composition for each new ink‐substrate system. While prior research has demonstrated modulation of interfacial adhesion using stamps made of shape‐memory polymers (SMP) that can change their contact area with inks using external stimuli, these were limited to only two adhesive states: continuous large-area contact with flattened features and small contact with raised features. Such bimodal adhesion controls limit the size of the printed features to the size of the continuous large stamp areas.

Technology Overview

Researchers at the University of Rochester have invented a method to pick up and transfer thin films of inorganic and/or organic materials, or stacks thereof, by inducing thermomechanical responses in shape-memory elastomers to modulate adhesive interactions. The elastomeric stamp is first deformed at an elevated temperature to achieve high contact area. Then, while maintaining deformation, the temperature is lowered to induce a transition of the shape-memory stamp into a significantly stiffer semi-crystalline or glassy state. This process fixes the stamp (or stamp features) into a temporary shape with a high contact area that is maintained when the deformation forces are removed. After shape-fixing, the good adhesive contact between the stamp and the film to be transferred should enable pick-up and transfer to a target location. The film release then is achieved by heating the deformed elastomeric stamp with the film which softens the material and eventually breaks adhesive contact. By optimizing the stamp feature geometry via a) prepatterning the elastomer with small geometrical features or b) using flat elastomers with enhanced surface roughness, it is possible to continuously modulate the stamp‐ink contact area through thermo‐mechanical SMP cycles, thus enabling tunable adhesive contacts between the individual stamp features and the inks.

Benefits

Such shape‐memory assisted transfer of thin film patterns could potentially increase print resolution to the sub‐micrometer scale by reducing the size of the ink features to the dimensions of the individual stamp features. Such contact area modulation removes the need to control adhesive interactions kinetically or through chemical modification. Potentially, this approach could be generalized to transfer different inks using identical printing conditions and materials.

Applications

Contact transfer printing

URV Reference Number: 2-19047
Patent Information:
Category(s):
Materials
For Information, Contact:
John Fahnervihtelic
Senior Licensing Manager
University of Rochester
585.276.6600
john.fahner-vihtelic@rochester.edu
Inventors:
Mitchell Anthamatten
Alexander Shestopalov
Keywords: