Composite Layer Stamp for Microcontact Printing

Technology #16796

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Clear PDMS bears the features, whereas a dye-loaded backing contains the fluorescent dye.
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Inventors
Professor David Hardt
Department of Mechanical Engineering, MIT
External Link (meche.mit.edu)
Muhammad Hawwa
King Fahd University of Petroleum and Minerals
Hussain Al-Qahtani
King Fahd University of Petroleum and Minerals
Scott Nill
Department of Mechanical Engineering, MIT
Larissa Nietner
Department of Mechanical Engineering, MIT
Hassen Ouakad
King Fahd University of Petroleum and Minerals
Managed By
Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Fluorescent Contact Imaging for In-Process Print Sensing

US Patent 9,678,011

Microcontact printing is a versatile process to create micro- and nano-scale patterns using an elastomeric stamp. The inventors created a novel layered stamp design that separates functional components of the stamp to allow for their greater individual control in the production and printing process. Layers of varying optical properties were used to integrate sensing components into the tool.

Applications

This technology has applications in the printing industry generally, specifically in soft lithography, imprint and microcontact printing of electronics. The ability to produce stamps with layers of varying properties leverages a great set of sensing and actuating methods which allow for the precise, high resolution, continuous and cost-effective printing of displays, circuits, photovoltaics and other devices on flexible substrates.

Problem Addressed

In microcontact printing, selective contact between the substrate and the micro- or nano-scale features on the stamp results in transfer of a molecular or fluid ink. Other layered stamps alter layer elasticity to improve mechanical properties of the stamp. This invention aims to vary optical properties instead. This allows for greater active control of the print process to meet rapidly increasing resolution demands of printed electronics.

Technology

The inventors developed a bi-/multi-layer PDMS (silicone) soft-lithography stamp. One layer is either chemically modified or doped with fluorescent particles or dye, so that functional groups, molecules or particles provide different optical or electrical properties. This stamp is used for microcontact printing. The stamp is produced by casting layers on top of each other. Each layer is entirely or partially crosslinked by the time the next layer is cast. The stamp material is cast into a centrifuge to create a seamless cylindrical stamp. To create the mold on the inner surface of the centrifuge, two layers of photoresistive polymer are applied to it: a fully-covering coat for creating a planar surface and a laser-structured layer that provides the pattern. The technique of varying optical properties allows for new methods of continuous inspection and control of the print process. Other functional properties can be introduced to the layers with regard to applications in advanced metrology and contact control; such layers could provide for various sensing, actuating or thermal control purposes.

Advantages 

  • Low-cost stamp
  • Few moving parts with more range of flexibility
  • Varied optical properties of layers allows for new methods of control and inspection during printing process