□ DGIST (President Kunwoo Lee) announced that a research team led by Prof. Jae Youn Hwang of the Department of Electrical Engineering and Computer Science, in collaboration with a research team led by Profs. Euiheon Chung and Hyuk Sang Kwon of GIST’s Department of Biomedical Science and Engineering, has developed an “AI-based thickness-optimized acoustic hologram (TOAH)” technology that directly optimizes the thickness of a 3D-printed lens to simultaneously and precisely stimulate multiple regions of the brain. The technology is characterized by its ability to precisely control the phase and amplitude of ultrasound waves through the lens, thereby generating three-dimensional ultrasound focal patterns of desired shapes.
□ Conventional ultrasound brain-stimulation technologies suffer from a critical limitation: When ultrasound passes through the rigid, irregular skull, the focal region becomes distorted and the energy delivered to multiple targets becomes non-uniform. Overcoming this limitation has required complex and expensive multichannel systems equipped with numerous ultrasound transducers.
□ Prof. Jae Youn Hwang’s research team achieved a breakthrough in addressing this challenge by combining artificial intelligence (AI) with physics-based optimization technology. To ensure that ultrasound accurately reaches multiple brain targets despite refraction by the skull, the AI directly designs the three-dimensional thickness profile of the lens to be fabricated using a 3D printer, thereby substantially reducing errors.
□ A key feature of this technology is its ability to enable multi-site brain stimulation using only a single thin 3D-printed lens and a single ultrasound transducer. It simultaneously and uniformly focuses ultrasound on multiple brain regions without the need for expensive equipment.
□ Experiments using rat skulls and simulation results showed that the newly developed technology (TOAH) formed ultrasound focal patterns far more accurately than conventional methods while delivering energy uniformly to multiple targets. It also significantly reduced skull-heating side effects by reducing unnecessary energy concentrated in the skull. Furthermore, simultaneous stimulation of the brains (bilateral thalamic regions) of rats with neuropathic pain using this technology demonstrated its effectiveness in reducing excessive neural activity and markedly improving pain responses. Simulations using human skull data also confirmed that focal accuracy and the balance of energy delivery across multiple targets were similarly improved.
□ “The key is that AI directly designs the structure of the lens, enabling ultrasound to be delivered accurately to multiple brain regions through the skull,” said Prof. Jae Youn Hwang of the Department of Electrical Engineering and Computer Science at DGIST. “By enabling precise multi-site brain stimulation using only a single ultrasound transducer and a 3D-printed lens, this technology could be expanded into a patient-tailored, non-invasive therapeutic platform that safely delivers energy without surgery or incisions for the treatment of not only pain but also neurodegenerative brain disorders as well as neurological and psychiatric disorders.”
□ This study was conducted with support from the Ministry of Science and ICT and the National Research Foundation of Korea’s Future Promising Convergence Technology Pioneer Program and Mid-Career Researcher Support Program. The study, with Dr. Moon Hwan Lee of DGIST (currently at the Max Planck Institute in Germany) as the first author and Prof. Jae Youn Hwang of DGIST and Profs. Euiheon Chung and Hyuk Sang Kwon of GIST as the corresponding authors, was published in the July 2026 issue of Brain Stimulation, a leading international journal in the field of brain stimulation.
