Graduate Student, Materials Science and Engineering

Office:
3714 Beckman Institute

Telephone: 217-244-2460
E-mail: rbarry@uiuc.edu

 

Three Dimensional structures using Robocasting

Three-dimensional micro-periodic materials have many potential applications, including but not limited to basic photonics, communications, sensors and more. Inverse opal templating is one of the approaches used here, as well as Robocaster direct drawing. Inverse opal templating involves forming an opal from self assembly of particles, and then infilling the structure with some other material, the original colloids can then be removed to yield the inverse structure. This method can easily be expanded past simple photonics into functional devices. There is considerable room for customization with selection and variation of the infilling material. We have already created a functional humidity sensor using this approach [1] and are working on additional devices. Robocasting is a direct drawing method using a computer controlled extrusion head that can raster in x, y and z dimensions. This moving nozzle can build up a structure to our specifications allowing for very robust and variable structure options. Our robocasting is done with a unique ink mixture we have devised that allows considerable strength while possessing elastomeric qualities, with additional optional steps to harden the structure. We are currently working to draw and characterize several interesting structures and explore other possible applications using our unique materials system.

Humidity Sensing Hydrogels

The effort put in on this project is warranted by the potential applications and useful properties of photonic crystals. One of those promising applications is for use as sensors. Currently, we are working on a hydrogel based photonic crystal humidity sensor. This system uses an inverse opal structure, resulting from filling the assembled colloidal photonic crystal with a polymer and cross linking the network, then removing the original colloids. This creates a negative image of the original structure, which lends itself more to the properties needed for good stop gap formation (that is, prohibition of certain wavelengths of light from propagating in the structure). Because of its chemical structure, the hydrogel responds strongly the presence of water in the air, causing a shift in the stop gap. This means that the color of reflected light from the material changes with ambient humidity.

 

References

[1] R.A. Barry, P. Wiltzius, Langmuir 22 (3), 1369-1374, 2006

People

• Prof. Pierre Wiltzius
• Dr. Masao Miyake
• Dr. Joe Geddes
• Robert Barry
• Andrew Brzezinski
• Christy Chen
• Sidhartha Gupta
• Vinayak Ramanan
• James Rinne