[16a-B508-1~10] 12.2 Characterization and Materials Physics

▲ [16a-B508-4] Fabrication of Dual-mode Miniature Surface Plasmon Resonance (SPR) Sensor Chips

〇(D)Wisansaya Jaikeandee¹, Supeera Nootchanat², Chutiparn Lertvachirapaiboon¹, Kazunari Shinbo¹, Keizo Kato¹, Sanong Ekgasit², Akira Baba¹ (1.Niigata Univ., 2.Chulalongkorn Uni.)

Keywords:Surface Plasmon Resonance, Norland Optical Adhesive 61, SPR sensor chip

In this work, a dual-mode miniature surface plasmon resonance (SPR) sensor chip was constructed using a grating-polymeric prism, as shown in Figure 1(A). Norland Optical Adhesive 61 (NOA 61) was chosen as an optical polymer for fabricating the grating-polymeric prism through soft lithography and the confined sessile drop technique. First, polydimethylsiloxane (PDMS) was used to replicate a uniform grating before drilling a hollow puncher with a diameter of 6 mm. Then, NOA 61 was dropped directly on the PDMS circular disk to get a hemispherical cap. Subsequently, the grating-polymeric prism was obtained after curing under UV irradiation. A gold film was deposited on the grating prism by thermal evaporation. After that, a 3D microfluid cell was designed for mounting with the grating-polymeric prism to achieve a dual-mode SPR sensor chip. The dual-mode SPR sensor chip was mounted on a motorized stage and characterized under wavelength modulation. The SPR excitation from the fabricated sensor can be observed in the visible and near-infrared regions by observing the incident angle from 45°-75°. In addition, it can provide two different modes of SPR excitation, including prism coupling (PC-SPR) and grating coupling (GC-SPR), as shown in Figure 1(B). To explicate the observable SPR excitation, the surface plasmon (SP) dispersion relation acquired from the dual-mode SPR sensor chip was plotted to confirm that PC-SPR mode (corresponds to +SP⁰ of the gold/NOA 61 prism) and GC-SPR mode (corresponds to -SP⁺¹ of the gold/air interface and gold/NOA 61 interface) could be excited from the fabricated sensor, as shown in Figure 1(C). In addition, the study of SPR excitation as a function of incident angle in DI water (n = 1.33) and refractive index in different concentrations (0%-50%) of ethylene glycol (n = 1.33-1.38) exhibited apparent changes in each SPR mode.