Novel Thin Film Materials for Large Area Electronics

The Palo Alto Research Center (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) in military environments. 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 been compatible with future roll-to-roll manufacturing. The sensor tape has integrated sensors, signal conditioning electronics, non-volatile memory and a thin film battery. The electronic circuits are based on jet-printed organic electronics with the emphasis on low-voltage electronics due to the limitations of the battery size. We integrate pressure, acoustic, acceleration and temperature sensors based on piezoelectric polymers such as PVDF or PVDF-TrFE copolymer. These materials were chosen because of low-power requirements, low drift and relatively simple fabrication. Polymer/polymer and polymer/small molecules blends are used in the fabrication of light sensors. Conventional fluorescence, fluorescence scanning near-field optical microscopy and atomic force microscopy have been combined to relate film morphology with photovoltaic and photoluminescence efficiencies as a function of surface treatment, concentration, and processing conditions. In this talk I will focus on the main challenges of the program: materials performance, TFT voltage operation, and inkjet printing as a manufacturing technology. Our design uses multiple sensors for each sensing parameter in order to reliably collect the data associated with blasts. The sensors are based on printed metal nanoparticle electrodes and membranes of piezoelectric polymer. We have also designed a printed non-volatile analog memory that operates without the use of A/D conversion. I will discuss the memory design and the parameters that influence voltage operation and data retention time. The electronics required to process the output of the sensors before writing data into the memory is based on printed CMOS. Currently we use solution processed p and n-type semiconducting materials that exhibit TFT mobility of 0.05cm2/Vs.

Bio:
Ana Claudia Arias is currently the Manager of the Printed Electronic Devices Area and a Member of Research Staff at PARC Inc (Palo Alto Research Center), Palo Alto, CA. At PARC she uses inkjet printing techniques to fabricate organic active matrix display backplanes for paper-like displays and flexible sensors. She came to PARC from Plastic Logic in Cambridge, UK where she led the semiconductor group, working in collaboration with chemical companies to develop polymeric semiconductors for thin film transistors. She did her PhD on semiconducting polymer blends for photovoltaic devices at the University of Cambridge, UK. Prior to that, she received her master and bachelor degrees in Physics from the Federal University of Paraná in Curitiba, Brazil. Her research work in Brazil focused on the use of semiconducting polymers for light emitting diodes. She the author of numerous papers and patents in the field of organic based electronic and optoelectronic devices and in printed electronics.