Graphene-Enhanced Refreshable Metasurface Expands Analytes of THz Label-Free Sensing and Achieves Picogram Limit of Detection
Y. F. Chen, Qingkang Wang, Kaiyu Wu
Abstract
THz sensing offers unique advantages including strong penetrability, low photon energy, and specific recognition of biomolecules and chemicals. However, current label-free THz sensors all operate below 1 THz, severely limiting applications as many drugs and chemicals vibrate at higher THz frequencies. Moreover, the THz detection of analytes at picogram levels is challenging. Here, a modern graphene-enhanced THz metasurface label-free sensor is presented. Its tunable resonance from ∼1.8 to 2.6 THz matches the fingerprint resonant frequencies of various analytes not currently detectable by label-free THz sensing. Quantitative detection of trace 1,3-DNB (absorbing at ∼2.52 THz) is first achieved with a maximum reflectance sensitivity of ∼10% pmol –1 and a detection limit of 42 pg. The sensor can also be refreshed, minimizing cost and being more environmentally friendly. Our strategy expands application scenarios of label-free THz sensing, enhancing its potential in fields such as the pharmaceutical industry, environmental monitoring, and security.