High-sensitivity nanophotonic sensors with passive trapping of analyte molecules in hot spots

Photonic sensors: trapping analytes by digging into nano-trenches An innovative sensor can make it easier to use infrared light for label-free, picogram-scale detection of amino acids and other molecules. Photonic sensors avoid the need for large quantities of analytes by using nanoscale gap structures to trap targets and subject them to ultrahigh optical fields. Peter Liu and colleagues at the State University of New York at Buffalo in the United States have developed a microchip that naturally drives molecules into nanoscale gap regions. The team fabricated arrays where aluminum ribbons overhang narrower strips of insulating crystals. When a drop of test solution is placed onto the chip and left to evaporate, surface tension creates concave profiles that concentrate molecules under the aluminum layers. The resonant frequencies within this device’s “nano-trenches” can be tuned to specific molecular targets by tweaking the array’s geometric parameters.