WashU develops portable OCT based on photonic integrated circuits

21 Feb 2024

Grant of $20 million will support research into platform for eye screening at lower cost.

A project at Washington University in St. Louis (WashU) is developing a portable OCT system based on photonic integrated circuits (PICs).

Supported by a grant of up to $20 million from the Advanced Research Projects Agency for Health (ARPA-H), the technology could offer advanced eye screening to more patients at lower cost, and find uses in other applications such as cardiology, dermatology, dentistry, endoscopy and urology.

The contract is part of ARPA-H's first call for proposals relating to "unconventional approaches to improving health outcomes across patient populations, communities, diseases and health conditions," to be achieved through breakthrough research and technological advancements.

"The integration of photonic and electronic integrated circuits simplifies the assembly process and lowers production costs, making OCT more accessible to a wider range of health care facilities and patients," commented WashU project leader Chao Zhou.

"Integrating components on a photonic chip also enhances overall stability and robustness, making these systems less susceptible to environmental influences and wear and tear, ensuring a longer lifespan and lower maintenance costs."

Zhao's previous work at WashU's Biomedical Engineering department included the 2020 development of space-division multiplexing (SDM) OCT, which takes advantage of the long coherence length of micro-electro-mechanical VCSEL laser sources to multiplex multiple images along a single imaging depth.

Although SDM-OCT is potentially 10 times faster than existing OCT scanners, useful in limiting the effects of patient movement, the SDM-OCT system required extensive time and labor to assemble components for each channel, which limited their broad use according to the WashU developers.

The new five-year project using PICs envisages assembling the system components in a photonic chip using current advances in CMOS manufacturing, and streamlining the production process so as to lower costs. Once a functioning device is available, the project will carry out studies using the device on adult and pediatric patients.

Photonic integrated circuits as transformative tech for healthcare

Integration of an OCT system's elements onto a chip has been the subject of much research, spurred by these potential clinical advantages. An EU project named OCTChip, concluded in 2021, investigated how to integrate optics and electronics for parallel swept-source OCT channels on a hybrid chip, including interferometer, photodetectors, amplifiers, and gigabit transceivers.

WashU's development of a new fully integrated PIC-OCT system will still face several challenges, commented the project team, which has divided the research effort into eight distinct stages ranging from developing components to testing.

Once achieved, however, the new system could be "more than 50 times faster than existing state-of-the-art commercial OCT systems at a fraction of the cost," noted the researchers.

At the end of its five-year project the team expects to have developed photonic and electronic chips and portable PIC-OCT prototypes specifically for ophthalmic imaging. Further optimization and integration of the photonic and electronic circuits could then lead to an integrated image acquisition and signal processing engine suitable for uses such as glucose sensing and portable skin imagers.

The ultimate goal for OCT is to move the technique nearer to becoming a true point-of-care option, as an example of how PIC technology can be transformative in areas other than communication and computing.

"Not only does this fully integrated PIC-OCT system outperform conventional OCT systems, but it also boasts excellent manufacturability and robustness and reduces device footprint," said Chao Zhou. "Mass production would significantly reduce manufacturing costs, paving the way for widespread future dissemination."