Research

Printed Electronics

In the coming age of more personalized medicine, data-driven diagnostics, and the “Internet of Things”, there is a fundamental need for research regarding flexible and low-cost electronic sensors. A promising approach to realizing such devices includes solution-processed fabrication of non-traditional electronic materials, specifically through printing.  Printed electronics can be defined as the additive deposition of liquid electronic materials onto substrates to form functional electronic devices. The field is particularly attractive due to the potential for high customization, low-cost when compared to vacuum-based deposition tools, and compatibility with flexible, stretchable, or even three-dimensional substrates. To move the field forward, the Andrews Laboratory for Printed Electronics and Sensors (LPES) focuses on three key aspects of printing electronics.

1. 

   Ink Development: While there have been many advancements and interesting technological breakthroughs in printable electronics, few have made it into the commercial market due to pitfalls including performance, reliability, and environmental robustness, primarily stemming from the inks used. Examples are abundant. The flexibility of solution-processed organic semiconductors does not outweigh the low electronic mobility and reliability. The high performance of printed carbon nanotube (CNTs) thin-film transistors is tempered by low uniformity. This motivates the development and discovery of new printable electronic inks. In particular, our lab is currently focusing on two ink-related projects:

• Developing doped silicon carbide nanowire-based inks to enable thin-film transistors capable of operating in extreme environments.
• Functionalizing CNTs using organic semiconducting polymers to form nanohybrid structures to be used in inks. This project will capitalize on the high mobility of CNTs with the high uniformity of organic semiconductors to fabricate next-generation flexible TFTs.

2. Sensor Development and Validation: The emergence of two general fields – the internet of things (IoT) and connected health care – motivates the development of novel electronic sensing devices. Our lab collaborates with experts in various fields, ranging from medical diagnostics to nuclear reactor technology development, to discuss parameters where new sensing is imperative. Next, we develop and design printable electronic devices to target the desired sensing application. This process is followed by fabrication and validation. The current sensor development projects in our lab include:

• Fully printed electronic biosensor for simultaneous detection of p24 antigen and HIV-antibodies for a portable, 4^th generation HIV diagnostic device.
• Active-matrix temperature and radiation sensing backplane for flexible spatially resolved physical parameter mapping. 

3. 

   Print Process Control Systems: Printed electronics offers the ability to additively manufacture electronic devices and systems. However, many print processes themselves (aerosol jet printing, inkjet printing, etc.) are excessively variable over time and therefore require trained operators throughout the printing process. Our lab seeks to mediate this by designing the appropriate feedback and associated controls for sustained printing operation. This work will begin with computational fluid dynamics to understand the temporal instabilities. Ultimately, the work will manifest itself in the design of novel control systems for continuous aerosol jet printing.