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Flexible printed sensor tape based on solution processed materials

Flexible Electronics Symposium

17 August 2010 - 18 August 2010
Binghamton, New York, USA



PARC is conducting a technical program to develop and prototype disposable flexible blast dosimeter tapes to detect the occurrence of events that cause traumatic brain injury (TBI). TBI is a medical condition that is cumulative and triggered by events such as blast pressure waves, noise, acceleration and possibly also extremely bright light. In order to meet the low cost target of the tapes, fabrication techniques such as inkjet printing, laser machining and lamination are employed with all deposition and patterning steps expected to be compatible with future roll-to-roll manufacturing. The sensor tape requires sensors, signal conditioning electronics, non-volatile memory and a thin-film battery. Jet-printed organic materials are used for electronic circuits; pressure, acoustic, acceleration and temperature sensors are based on piezoelectric polymers, and light sensors are fabricated using jet-printed polymer/polymer blends. These materials were chosen because of low-power requirements, atmospheric stability, low drift and relatively simple fabrication.

In this talk I will focus on the main challenges of the program: materials performance, TFT operation, and inkjet printing as a manufacturing technology. We have demonstrated p-type TFTs with a mobility up to 1.6 cm2 V-1 s-1 and n-type TFTs with a mobility up to 0.8 cm2 V-1 s-1. We have characterized the charge trapping rates for n- and p-channel devices and assessed the inverter gain and noise margin. All printed inverters showed a typical gain of 8 with VDD at 10V and -3dB cutoff at 150 kHz for a load of 0.02pF. We have integrated printed inverters with printed accelerometers, printed acoustic and pressure sensors and showed operation between 0-1000g, 100-140dB and 5-100 psi respectively. All-printed photosensors show a relatively linear response at high illuminance (100-400 klux).