Fabrication and measurement of microtip-array-based LSPR sensor using bundle fiber

In this paper, we present a micro electro mechanical systems (MEMS)-technology-based localized surface plasmon resonance (LSPR) sensor using a uniformly distributed noble metal nanostructure array on a silicon microtip. The conventional LSPR sensor based on chemically synthesized metal nanoparticles exhibits a lack of reproducibility, which is caused by rearrangement and irregular sizes of metal nanoparticles. This problem strongly affects the LSPR sensing performance and reliability. To overcome this problem, we propose a novel fabrication process of the LSPR sensor using the microtip. The deposited gold is exposed using a self-aligned etching process at the tip end and it is used as gold nanoparticles. The whole process for the fabrication of the microtip is possible using a single photolithography mask. The detailed fabrication process is introduced and analyzed. In addition, the improved reproducibility in terms of fabrication and measurement of the fabricated sensor is assessed by reliability tests. Moreover, the LSPR signals with varying refractive indices of media are measured to verify the feasibility of the microtip-based LSPR sensor system.