Abstract
This study experimentally analyses the binding characteristics of analytes mixed in liquid samples flowing along a micro-channel to the receptor fixed on the wall of the micro-channel to provide design tools and data for a microfluidic-based biosensor. The binding or detection characteristics are analyzed experimentally by counting the number of analytes bound to the receptor, with sample analyte concentration, sample flow rate, and the position of the receptor along the micro-channel length as the main variables. A mathematical model is also proposed to predict the number of analytes transported and bound to the receptor based on a probability density function for Brownian motion. The coefficient in the mathematical model is obtained by using a dimensionless mathematical model and the experimental results. The coefficient remains valid for all different conditions of the sample analyte concentration, flow rate, and the position of the receptor, which implies the possibility of deriving a generalized model. Based on the mathematical model derived from mathematical and experimental analysis on the detection characteristics of the microfluidic-based biosensor depending on previously mentioned variables and the height of the micro-channel, this study suggests a design for a microfluidic-based biosensor by predicting the binding efficiency according to the channel height. The results show the binding efficiency increases as the flow rate decreases and as the receptor is placed closer to the sample-injecting inlet, but is unaffected by sample concentration.
Highlights
Adapting micro/nano-channels or beads for higher surface-to-volume ratio is an effective method to increase the binding probability between low concentration of analytes in liquid samples and receptors fixed on the surface of the channels or beads such as micro-fluidic biosensor [1,14,15,16,17]
This article investigates experimentally and mathematically the process of analyte-receptor binding within the channel for a microfluidic biosensor
A mathematical model is proposed based on the probability density function for Brownian motion
Summary
Detection using biosensors is achieved through a process in which measurable optical or electrical signals are derived from the binding of an analyte and a receptor specific to this analyte (Figure 1a) [2,3,4,5]. A wide variety of studies are being conducted on improving the binding efficiency between analytes and receptors, or the signal efficiency and intensity from the analyte-receptor binding [9,10,11,12,13]. Adapting micro/nano-channels or beads for higher surface-to-volume ratio is an effective method to increase the binding probability between low concentration of analytes in liquid samples and receptors fixed on the surface of the channels or beads such as micro-fluidic biosensor [1,14,15,16,17]
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