Fingertip Touch-based Non-invasive Glucose Sensor Using Visible Laser Light in a SiO2-Au-SiO2 Coated Prism: Design and Implementation Using the Matrix Method
S.P. Dash, M. Hota and S.K. Triapthy
Electromagnetic waves still show a great interest in non-invasive blood glucose detection (BGD). Near infrared (NIR), which is heavily used for this purpose, suffers due to cost, low absorption in biological chromospheres, and stratum corneum, and accuracy. One of the candidates that has not been widely investigated for BGD is visible laser light. Compared to NIR, the refractive index of red laser light is more sensitive to the variations in glucose level concentration resulting in faster response times. Red laser light also demonstrates both higher linearity and accuracy for BGD. On the other hand, a visible laser source is essential to realize low-cost sensor devices. The difficulty in using red laser for BGD is its low penetration depth. Long range surface plasmon resonance (LRSPR) can considerably improve the penetration depth. In this paper we designed and simulated with finite difference time domain (FDTD) a fingertip touch based non-invasive glucose sensor with LRSPR using a visible laser diode (LD) in an insulator-metal-insulator (IMI) structure coated onto a glass prism employing the matrix method. The results show that a symmetric design of SiO2-Au-SiO2 (420 nm – 50 nm – 420 nm) is necessary for achieving better sensitivity. Besides, a considerable improvement in the SPR dip for sensing application was observed when BK7 is used as a glass material. The detection limit and the sensitivity of detection of the proposed sensor are calculated and found to be 3.1 mM and 0.0139 o/mg/dl, respectively. The simulated model concludes a great potential towards the fabrication of a low cost, non-invasive glucose sensor based on visible laser light.
Keywords: Laser diode (LD), insulator-metal-insulator (IMI) structure, glucose detection, blood glucose detection (BGD), visible laser light, non-invasive biosensor, long range surface plasmon resonance (LRSPR), finite difference time domain (FDTD)