Our Current Research Projects at WashU

Stretchable Electronics for Display, Sensing, and Energy Harvesting Applications

In this project, our group aims to develop a large-area intrinsically stretchable electronic system comprising monolithically integrated sensors and display elements, fabricated entirely using a low-cost printing process. Such a system can be considered as a smart fabric, which is extremely lightweight, can be stretched by at least 50% to allow conformable coverage of curved surfaces, and capable of displaying information and sensing various stimuli such as pressure, strain, temperature, light, etc. Such a system could find a wide range of applications in consumer electronic devices such as stretchable display, wearable electronics for health monitoring, biomedical devices, and soft robotics areas.

Key Publications:

Low-Cost Additive Manufacturing of Flexible and Stretchable Electronics Using Inkjet Printing

We develop various types of electronic inks in-house for scalable fabrication of electronic devices and circuits on both elastic and plastic substrates.

Key Publications:

High-Performance Nanoelectronics and Optoelectronics Using 2-Dimensional Semiconductors

Our group studies a variety of 2-dimensional semiconductors such as black phosphorous and transition metal dichalcogenides that are atomically-thin. We explore their electronic and optoelectronic applications as high-performance transistors, sensors, photodetectors, infrared imagers, and so on.

Key Publications:

Devices for Energy Conversion: Actuator & Energy Harvester

In collaboration with Nelson Sepulveda at Michigan State University, we have demonstrated that it is possible to combine smart materials with complementary advantages to achieve close-to-ideal photothermal actuators (devices that convert energy from light into mechanical work) with high efficiency, fast response, and high energy density. In addition, we also study devices that can realize bi-directional conversion between mechanical energy and electrical energy. Examples include a flexible thin patch that can be used as a nanogenerator to harvest energy from human motion, as well as being operated in the opposite direction as a flexible thin-film loudspeaker when electrical signals are applied. The above energy conversion devices may find applications in wearable devices or as a propulsion mechanism for micro-sized robots.

Key Publications:

Dr. Wang’s Past Research During PhD & Postdoc

Roadmap of Our Early Work on Carbon nanotube Electronics

Two review papers about our early work on carbon nanotube electronics: 

System-Level Flexible Electronics Using Inorganic Nanomaterials

We have demonstrated heterogeneous integration of various types of nanomaterials-based electronic devices for “system-on-plastic” applications. Examples include user-interactive electronic skin, full-color AMOLED display, integrated circuits, and high speed (ft >100 GHz) transistors built on ultrathin flexible substrates.

Key Publications: 

Nanomaterials-Based Radio-Frequency Electronic Devices

We have developed a self-aligned T-gate platform for fabricating high-performance short channel RF transistors with minimized parasitic capacitance using carbon nanotubes, graphene, and 2D III-V nanomembranes.

Key Publications: 

Solution-Processed Semiconducting Carbon Nanotube Network for Macroelectronics Applications

We were one of the first to report a highly-scalable, low-cost, and solution-based platform for wafer-scale deposition of high purity semiconducting carbo nanotube thin film back in 2009. This material platform was subsequently used in numerous device applications including both p-type and n-type thin-film transistors, CMOS integrated circuits, RF electronics, display electronics, transparent electronics, flexible electronics, and printed electronics. 

Key Publications: 

Electronic Type- and Chirality-Controlled Synthesis of Carbon Nanotubes

CVD growth of aligned carbon nanotubes with well-defined electronic type (metallic vs. semiconducting) and chirality was achieved. 

Key Publications: 

CVD-Growth of Horizontally Aligned Carbon Nanotubes for Nanoelectronics Applications

In this project, we have demonstrated wafer-scale CVD growth and transfer of high density aligned carbon nanotubes for high-performance field-effect transistors and CMOS integrated circuits.

Key Publications: