667975 event 1685733229 1685741829 <![CDATA[Ph.D. Dissertation Defense - Devin Brown]]> Title:  Nanoscale Strain Gauges in Flexible Polymer for Biological Cell Force Measurement

Committee:

Dr. Oliver Brand, ECE, Chair, Advisor

Dr. Wilbur Lam, BME

Dr. Muhannad Bakir, ECE

Dr. Azadeh Ansari, ECE

Dr. Fatih Sarioglu, ECE

]]> The goal of this work is to transduce blood platelet cell contractile forces in the 1-100 nN range to a change in measured electrical signals using nanoscale strain gauges. Currently, most cellular force measurement methods utilize optical techniques that examine before and after high resolution images of soft pillar deflections or micro-dot displacement. These approaches are time consuming and produce limited data due to image analysis. Other MEMS based (e.g. cantilever, rotor, or micro-gripper) approaches can transduce signals but typically have form factors too large to work with 2-3 micron diameter platelets or would occupy excessive space when scaled up. The aim of this thesis is threefold: 1) to develop a device appropriately sized to interact with platelets, 2) to create a device which could measure a signal in real time, and 3) to create a device that is able to be scaled to measure thousands of platelets simultaneously. Two different fabrication approaches are investigated to achieve these goals. The first approach embeds a nanoscale metal strain gauge in soft polymer using a transfer process. Platelets could then be applied to the polymer surface and their compressive surface strain would be coupled into shallow underlying strain gauges. The second approach suspends a nanoscale wire over a cavity in conventional silicon based fabrication materials. SU-8 pillars are placed on the suspended nanowires and lateral compressive forces from platelets would deflect the pillars and create strain in the suspended nanowires.

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