Title: Implantable Optoelectronic Devices for Deep-Brain Neural Modulation and Sensing
Recent progresses in the design of mechanics and materials have given birth to flexible and stretchable electronics and photonics, enabling the integration of rigid inorganic devices with soft, elastic and curved biological systems. While current flexible photonic devices are mostly based on organic materials, bio-integrated high performance inorganic optoelectronic devices will provide new insights on interactions between light and bio-systems. Here we present unconventional strategies to design and fabricate thin-film, microscale III-V based optoelectronic devices and use them in implantable systems for biomedical applications. Specifically, high performance InGaN and GaAs based LEDs and photodetectors with dimensions less than 100 um and thicknesses less than 5 um are formed by epitaxial liftoff methods. These devices are integrated with organic based substrates to realize unusual flexibility and stretchability. In addition, the organic/inorganic interfaces are studied and optimized to achieve ideal optical, electrical and thermal performance. Furthermore, the integrated microscale devices are implanted into living animals for biological signal sensing and stimulation. Specifically, LEDs are utilized to work as light sources to interact with genetically encoded neural actuators, stimulating neural activities, while photodetectors are used to monitor the fluorescence signals of light sensitive proteins, probing neural signals. Optical simulation methods are developed to understand the light propagation in deep brain tissue and optimize the device structures. Encapsulation schemes are developed to obtain prolonged device lifetime and improved biocompatibilities in living biological systems. Implanted devices are wirelessly powered and controlled by a miniaturized circuit system. These devices are implanted deeply into the mouse brain, demonstrating close loop monitoring and manipulation of neural activity in vivo. Such an integrated, deeply implanted and microscale optoelectronic system provides new insights on interactions between optical signals and neural systems.
Xing Sheng is currently an assistant professor in the Department of Electronic Engineering at Tsinghua University, China. He obtained his PhD degree at Massachusetts Institute of Technology in 2012, and his B.Eng degree at Tsinghua University in 2007. From 2012 to 2015, he was a postdoctoral researcher at University of Illinois at Urbana-Champaign. His awards and honors include Best Poster Award (2nd prize) in Nature Conference on Flexible Electronics, Nanjing, 1000 Plan Program for Young Talents, Gordon Engineering Leadership Teaching Assistantship, etc. His research interests include Non-conventional optoelectronics for biomedical applications; Silicon, III-V and tandem thin-film solar cells and concentrators;Photonic integrated circuits; Inorganic (Si, Ge and III-V) thin-film photonic devices (photodetectors, LEDs, lasers, etc); Biocompatible and biodegradable photonics.