Researchers from Spain develop an ideal device for molecular detection using advanced infrared techniques.
A visionary on-chip device capable of identifying molecules by analysing their unique vibrational “fingerprints” has been developed by a team of researchers from CIC nanoGUNE, Spain. The development uses exotic light rays, known as hyperbolic phonon polaritons (HPhPs), within a graphene-based infrared detector. This approach significantly enhances sensitivity and enables the detection of nanometre-thin molecular layers, all while operating at room temperature.
Molecular identification hinges on detecting specific vibrational frequencies when illuminated with infrared light. Traditional infrared spectroscopy, while effective, struggles with weak signals due to the mismatch between molecular size and infrared wavelengths. Recent advances in surface-enhanced infrared absorption (SEIRA) spectroscopy have addressed this by using metallic nanostructures to amplify molecular signals.
“Phonon polaritons, especially in thin layers of hexagonal boron nitride (h-BN), offer ultra-high field confinement and long lifetimes,” explains Prof. Rainer Hillenbrand, CIC nanoGUNE. These properties make them ideal for boosting SEIRA’s sensitivity. However, SEIRA has historically relied on bulky equipment, limiting its scalability for on-chip applications. The new device is poised to benefit a diverse audience, ranging from researchers and medical professionals to environmental scientists, by offering compact, high-sensitivity tools for molecular analysis and diagnostics.
To overcome these challenges, researchers combined SEIRA advancements with graphene-based detectors that operate at room temperature. “We demonstrated that phonon polaritons can be electrically detected, enhancing detector sensitivity,” adds Prof. Frank Koppens, ICFO. The result is the first-ever on-chip SEIRA detection of molecular vibrations, achieved through collaborative efforts between NanoGUNE, ICFO, and theoretical support from leading physics centres.
Using ultra-confined HPhPs, the device directly detects molecular fingerprints in a graphene detector’s photocurrent, eliminating the need for traditional infrared detectors. Dr. Sebastián Castilla, ICFO highlights the potential of this technology: “By integrating this detector with microfluidic channels, we could create a true ‘lab-on-a-chip,’ ideal for medical diagnostics and environmental monitoring.”
Dr. Andrei Bylinkin, nanoGUNE envisions a future where compact infrared detectors integrated into smartphones or wearables could enable rapid molecular identification, revolutionizing fields from healthcare to environmental science. “This marks a pivotal step towards sensitive, portable spectroscopy at room temperature,” he concludes.
