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Senior Project: Inkjet Printed Transistor

Worked under Dr. Tina Smilkstein with Nick Kaperilian and Neil Lamon to research the possibility of utilizing a Fujifilm Dimatix inkjet materials printer to produce an inkjet printed transistor. We ran into production issues that prevented the creation of functional transistors.

Abstract

Wearable sensors currently use off-the-shelf integrated circuits for signal amplification. These fabricated ICs have packages that make attaching them to a wearable substrate difficult; current integrated circuits would be too bulky for most uses in wearable technology and the silicone is not at all flexible. The current integrated circuits also have a slow turnaround time and are typically much more expensive to fabricate. Wearable substrate-based printed transistors (like an adhesive band-aid patch) eliminate the need to use fabricated amplifier ICs. This project's end goal is to print and characterize transistors on a wearable substrate and use them to build a simple amplification circuit to reduce cost and manufacturing time associated with wearable sensor fabrication. Over existing manufacturing techniques inkjet fabrication would allows for faster and lower cost changes to transistor designs and reduces the cost of very small production run integrated electronics by avoiding the expensive photolithography process used today. In addition, the inkjet process could open the door to more sustainable and biodegradable materials to be used in electronics. Our attempts at creating an usable inkjet based transistor were not successful. We ran into significant problems with the choice of dielectric; the original dielectric that we picked had barriers of use that we couldn't overcome: the toxicity and light-sensitivity. We spent a large amount of time trying to find a way to make it work and then even longer trying to find a replacement. We decided to go with zinc oxide. Zinc oxide brought with it its own troubles, but they were less significant than the issues with the photoresist. We believe with a few minor alterations, our composition could definitely be successful and it would be an improvement from the model we based our design off of. We believe if we could do the entire printing process, from filling the ink cartridges to the final round of printing and curing, consecutively, our design and process would have been highly successful.

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© Joseph Eckstein 2018