Session 8: Direct Write & 3D Printing I

Aerosol Jet Printed Carbon-Nanotube-Network Thin-Film-Transistors on Flexible Substrates
Wednesday, February 14, 2018
11:10 AM - 11:30 AM

The printed flexible electronic devices has attracted large interests because of the promise of these devices for cost-effective and scalable production. They also do not require fabrication of masks or templates which provide significant design flexibility compared to the traditional photolithography process. Aerosol jet, as one of the thriving printing solutions, can be used to deposit wide range of materials such as metal, dielectrics, and carbon nanotubes (CNTs) because it is capable of handling inks with viscosity as large as 1000 cP. The superior compatibility of aerosol jet printing with flexible substrate makes it one of the excellent techniques for the fabrication of future wearable devices. In this work, CNT network based thin film transistors (TFTs) is printed on flexible substrate by Optomec aerosol jet 200 system. Novele IJ-220 PET is used as flexible substrate and JS-B25P silver ink for metallic contacts of TFTs. The mesoporous surface of this flexible PET substrate can promote uniform deposition and strong adhesion, which can be cured after printing inks at room temperature. Low temperature Atomic layer deposition (ALD) is used to deposit thin layer of Al2O3 as gate-dielectric of TFTs. The overall low temperature processing can avoid major deformation of the substrate, which not only helps in increasing the accuracy of alignment to reach resolution less than 10µm, but also makes possible the printing of other materials conveniently. The printed flexible CNT-TFTs will be used as gas sensor to detect NO2, NH3, and other gases such as organic vapors at low ppm level. These sensors can be used for monitoring hazardous molecules, vehicle and industrial emission control as well as environmental pollution identification.