The Micro-ring resonator detector can determine the speed of blood flow and the oxygen metabolic rate at the back of the eye. This information could help diagnose such common and debilitating diseases as macular degeneration and diabetes. The tiny, transparent device can fit into a contact lens, and could help a range of scientific endeavors from biomedicine to geology.
The Micro-ring device builds upon prior work to develop photoacoustic imaging, which combines sound and light waves to create images of biological materials. The imaging technique is being studied for both fundamental biological investigations and clinical diagnosis from nanoscopic cellular imaging to human breast cancer screening.
The prior work in retinal imaging technologies led to the development of the current diagnostic device, which required a large bandwidth for spatial resolution, as well as optical transparency to allow light to pass through freely. Ultrasound detection devices were previously bulky, opaque, and lacked sufficient sensitivity.
The radically different type of detector is small enough to be used with human eyes, soft enough to be integrated into a contact lens, and generates a super-high resolution of hundreds of megahertz. The first iteration of the device placed the needle-sized detector on the eyelid, but that method was not ideal. The next iteration was a tiny ring implanted in a single-use contact lens worn during diagnosis, which added the extra challenge of making the device transparent. The resulting plastic Microring resonator is a transparent device that is 60 micrometers in diameter and 1 micron high.
Potential applications for the device are for studying the optics of breast cancer cells — information that could lead to new treatments. The device could also be used by neuroscientists as a window into rodent brains for studying drug protection for the cortex during different points of a stroke. Typically, researchers use a pure piece of glass, but the new device allows for more types of imaging.
Geologists could use the technology to investigate the Earth's crust and earthquakes.