Novel Photonic Bio-Chip Sensor Based on Strained Graphene Sheets for Blood Cell Sorting.

Fatemeh Ghasemi,Sepehr Razi

doi:10.3390/molecules26185585

Abstract

A photonic biochip with a tunable response in the visible range is suggested for blood cell sorting applications. Multi-layers of ZnS and Ge slabs (as the main building blocks), hosting a cell in which bio-sample could be injected, are considered as the core of the sensor. In order to increase the sensitivity of the chip, the bio-cell is capsulated inside air slabs, and its walls are coated with graphene sheets. Paying special attention to white and red blood components, the optimum values for structural parameters are extracted first. Tunability of the sensor detectivity is then explored by finding the role of the probe light incident angle, as well as its polarization. The strain of the graphene layer and angle in which it is applied are also suggested to further improve the performance tunability. Results reflect that the biochip can effectively identify selected components through their induced different optical features, besides of the different figure of merit and sensitivity amounts that are recorded for them by the sensor.

Highlights

For more than two decades, remarkable efforts have been made to design and fabricate label-free, photonic chips for the fast detection of the key agents in biological solutions [1]
A multilayer photonic bio-chip based on alternating slabs of ZnS and Ge semiconductors and a single bio-cell with graphene covered walls was suggested for the detection of blood components
The results indicated that the isolation of the bio-cell with the air slabs has a significant effect on the performance of the chip

Summary

Introduction

For more than two decades, remarkable efforts have been made to design and fabricate label-free, photonic chips for the fast detection of the key agents in biological solutions [1]. As the dielectric constants of the WBC and RBC components are different, their role in these optical changes will be different and their detection via the suggested bio-chip would be possible It is worth noting, as just a single monolayer of graphene has been considered on each wall, the large non-zero imaginary dielectric constant of graphene cannot cause a significant damping effect on the probe light intensity. When we try to optimize the bio-chip response in this wavelength range, it is in line with that finding and makes it possible to reduce the bio-chip size into nanometer levels Another advantage of using graphene in the suggested sensor is related to the extra tunability in the sensor’s performance (that the graphene layer causes). To the best of our knowledge, studying the effect of linear (uniaxial) strains on the sensitivity of a graphene-based bio-sensor has not been reported before, and this research is the first study in this regard

Theoretical Approach

Results and Discussions

Incident Angle Dependency

Conclusions