Contactless Glucose Sensing at Sub‐Micromole Level Using a Deep‐Subwavelength Decimeter‐Wave Plasmonic Resonator
Xuanru Zhang, Tie Jun Cui
Abstract
Abstract Microwave resonance sensing has found a wide variety of applications and exhibits promising potentials in compact integrated sensors. However, its distinguishing ability to trace‐amount targets remains challenging, which can be characterized by the effective wavelength and the quality factor (Q‐factor). Here, a contactless sensing scheme for detecting sub‐micromole glucose using a deep‐subwavelength spoof localized surface plasmon (SLSP) resonator working at the decimeter‐wave band is proposed. The SLSP resonator sustains a mixed‐mode of an electric monopole and a magnetic dipole, compressing the electromagnetic mode into a diameter smaller than λ 0 /41 ( λ 0 is the free‐space wavelength) and achieving a measured Q‐factor of 187. In experiments, contactless sensing has been realized using a polydimethylsiloxane (PDMS) microfluidic channel, which separates the resonator and the solution. The solution sample under test features an ultra‐compact volume of 3.7 × 10 –8 λ 0 3 , and a detection limit of 0.45 µmol glucose is demonstrated. This work envisions the applications of spoof localized surface plasmons in the contactless and trace‐amount biomedical sensing.