The key to the technique, according to Associate Professor Karl Böhringer in the UW's Department of Electrical Engineering, lies in temperature-driven changes in the material with which the less-than-one-millimeter-wide electric heaters are coated. Proteins stick to the material as its temperature rises, and release when it goes back down. That, according to Böhringer, opens the door to a wide array of possibilities.
"The proteins stick locally to the areas we heat, and we can stick cells to the proteins," he said. "This provides a relatively simple, low cost way of creating cell chips to run experiments and to create other useful devices."
Böhringer and colleague Buddy Ratner, director of the UW Engineered Biomaterials program, presented the research recently at the 12th International Conference on Solid-State Sensors, Actuators and Microsystems in Boston, and a patent is pending for the process.
To make the chips, researchers started with a thin slide of glass, on which they built arrays of microheaters using lithographic techniques. They then deposited poly-N-isopropylacrylamide (pNIPAM), a temperature sensitive polymer, onto the microheater arrays.
At temperatures below about 90 degrees Fahrenheit in a liquid environment, the polymer exists in a water-saturated, gel-like state. But when the temperature exceeds that threshold, the polymer's chemical properties change. It becomes water-repellant and allows proteins to stick to it.
"When you go above this low critical solution temperature, there is a transition from the gel-like wet state to a dry, more den
Contact: Rob Harrill
University of Washington