ECE PhD Defense: Guo Chen

ECE PhD Defense: Guo Chen

Title: Optoacoustic neuromodulation mediated by fiber devices and blood.

Presenter: Guo Chen

Advisor: Professor Chen Yang

Chair: TBA

Committee: Professor Chen Yang, Professor Ji-Xin Cheng, Prof. David Boas, Prof. Jerome Mertz.

Google Scholar Link: https://scholar.google.com/citations?user=be26MdAAAAAJ&hl=en

Abstract: Neuromodulation has become an essential tool for probing and treating the nervous system, offering precise control of neural activity through electrical, magnetic, acoustic, optical, or chemical approaches. By enabling targeted and reversible manipulation, neuromodulation supports causal investigations of brain function and provides effective therapeutic strategies for conditions such as Parkinson’s disease, epilepsy, chronic pain, and treatment-resistant depression. Recent advances in minimally invasive and noninvasive techniques—including focused ultrasound, transcranial magnetic stimulation, and emerging photoacoustic (PA) stimulation—are further expanding access to deep-brain targets while reducing systemic side effects.

Despite rapid progress, key obstacles limit the broader adoption of PA neuromodulation. Current PA emitters exhibit suboptimal optoacoustic conversion efficiency, requiring high optical fluence that elevates the risk of photothermal toxicity and constrains long-term use. In addition, the underlying biophysical mechanism of PA neuromodulation remains insufficiently understood. Extending PA neuromodulation into in vivo applications introduces further challenges related to device stability, biocompatibility, and compatibility with widely used brain-recording platforms, including calcium imaging, electrophysiology, and integrated multimodal systems.

To address these limitations, this thesis presents a next-generation PA emitter architecture with a ten-fold improvement in conversion efficiency, enabling safer and more energy-efficient stimulation. This enhanced performance provides the foundation for mechanistic studies at the cellular scale. Furthermore, an optical imaging system was designed to capture direct optical evidence for understanding the PA modulation mechanism. Finally, a novel in vivo PA neuromodulation strategy was demonstrated that uses blood as an endogenous absorber, achieving excellent compatibility with existing brain-imaging technologies. Together, these advances establish a robust framework for non-genetic, high-precision PA neuromodulation both in vitro and in vivo.