麻豆淫院

A new breakthrough in the field of physics led by doctoral student Yueming Yan could allow for the creation of small, thin, low-power optical devices to be used in both medical imaging and environmental sensing.

In a study in Science Advances, Yan and his colleagues, including Associate Professor of Chemistry Janet Macdonald and Stevenson Professor of 麻豆淫院ics Richard Haglund, examined tiny nanoparticles of metals and semiconductors, specifically gold and copper.

The team laid down two ultrathin layers of gold and semiconducting copper sulfide nanoparticles, creating a "sandwich" 100 times thinner than a human hair. They then zapped this sandwich with a flash of light shorter than a trillionth of a second. Doing so caused the particles to "chat" back and forth, exchanging energy so efficiently that they re-emitted light in multiple different colors.

"It is like the way bowing a violin string can produce higher acoustic overtones," Yan said. "By shifting the layers closer together or farther apart and measuring how quickly the light flashes changed, we discovered a new, lightning-fast energy exchange between metal and semiconductor particles."

This process is called resonant energy transfer, and it is effective for many different metal and semiconductor nanoparticles, converting infrared light into visible and even ultraviolet colors.

Yan said this process could be integrated with on-chip lasers, which are miniature lasers fabricated directly onto a circuit or chip. Such lasers are already essential components of applications in optical communication, quantum information processing, and health care.

"In health care, a wearable, bandage-sized imaging patch could sense growth of healthy tissue and simultaneously monitor scarring," Yan said.

"For example, the device described in our paper produces green and blue light. The green light monitors the growth of healthy tissue, while the blue light is sensitive to scar tissue. A physician can distinguish healthy dermal collagen from scar tissue by monitoring the ratio of green to blue light and adjust treatment accordingly."

The process could also aid in environmental sensing through an ultrathin sensor woven into clothing or painted onto walls to detect pollutants, gas leaks, and pathogens with unprecedented sensitivity.

Yan said a single sensor could emit visible and ultraviolet signals to monitor both air and water quality. When pumped with near-infrared light, the sensor efficiently produces both visible light, which is strongly absorbed by nitrogen oxides from automobile exhaust, and ultraviolet light, which is absorbed by pollutants in water.

"Ultimately," Yan said, "these nanometer-thin films could replace bulky optical sensors with flexible, wearable, or even implantable devices, thus transforming health and safety technologies."