[Brand-New Ge₂₀Ga₅Sb₁₀S₆₅ Prism Biosensor Based on Inverted SPR]

Based on inverted surface plasmon resonance (ISPR) a novel biosensor consisting of Ge₂₀Ga₅Sb₁₀S₆₅-palladium-graphene layer-biomolecule layer is proposed. The refractive index of biomolecule layer alters as biomolecule experience interactions, thus leading to a shift of ISPR angle. On this basis, the spectrum output of sensor is derived by transfer matrix method. The sensitivity, the resolution, the dynamic detection range and the signal to noise ratio of the presented sensor are discussed and compared with the performance of traditional sensors. Moreover, the influences of grapheme layer thickness on sensors are analyzed with comparative study. Finally, near infrared is used as the incident light of the presented sensor. The results show that, the best thickness of grapheme layer is monolayer; the peak intensity of the ISPR reflection is about 80%~90% of intensity of incident light, guaranteeing a high signal to noise ratio; In the visible light, when λ = 632.8 nm, the presented sensor is 1.9 times the resolution of the sensor based on SiO₂ coupling inverted surface plasmon resonance, is 3. 5 times the resolution of the sensor based on surface plasmon resonance(SPR), and is 2 times the dynamic detection range of pre-existing biosensor based on SPR. The application of Ge₂₀Ga₅Sb₁₀S65 prism extends the detection light wavelength from the visible region to the near infrared region. When λ = 1,000 nm, the sensor is 3-4 times of the sensor in visible region. The research greatly contributes to the realization and application of biosensor based on inverted surface plasmon resonance.