Prof. Chii-Wann Lin
Medical Micro Sensor and System Laboratory
Institute of Applied Mechanics
National Taiwan University
Title : Pervasive Biosensing with Advanced Surface Plasmon Resonance Technologies
Biosensors exploiting mobile phone technology are emerging as a promising solution to solve point-of-care issues. For pervasive sensing platform, we proposed a “smart” DNA biosensor combining single-wavelength colorimetry and digital Lock-in Amplifier within a smartphone is proposed.We successfully demonstrated a cost-effective and portable sLIA optical detection platform that is applied to DNA detection using gold nanoparticle (AuNP) colorimetry. The implemented sLIA suppresses the 1/f noise and the intrinsic noise from audio phone jack. Due to the digital Lock-in amplifier implemented within the system, the measurement noise-to-signal ratio is greatly reduce to -63 dB. Taking advantage of the improved NSR, our platform demonstrate a Limit-Of-Detection (LOD) at 1.34 nM in AuNP colorimetry DNA sensing for the considered wavelength. Secondly, we demonstrated a novel phase interrogation of SPR sensing mechanism called Shearing Interferometer based Surface Plasmon Resonance (SiSPR) biosensor. Through the shearing interferometer chip design, wave-front division/beam recombination is carried out within the chip. To extract the phase information from such SiSPR system, “a” is set to 3.8317 while performing a modified generalized LIA on the interfeogram. The controlling of phase modulation depth is relying on precise estimation of wavelength-to-current sensitivity factor and I-V characteristic of the laser diode. Typically, S is around 0.6~1.1 nm/mA. We will demonstrate how reflective layer thickness and glass quality strongly affect the contrast of the SiSPR and thereby it final measurement performances. Finally, a glucose standard solutions series are used to construct the phase response curve of the SiSPR device. The sensitivity the SiSPR is around 2.3x10-6 RIU with a dynamic range of 7.0x10-3 RIU.