Hit or Miss: Sensor Design via Scaled Collision Theory

Abstract

The working characteristics of targeted surface sensing systems—such as fluid velocity and concentration limits—have mostly been explored through experimental trials. Here we develop a novel scaled collision theory to facilitate the experimental screening process in determining the optimal system parameters specific to sensing discrete molecular or particulate targets with low concentration in a bulk fluid system, such as biomarkers, pollutants, or explosives. A simple fluid sensor system was developed and subjected to steady-state Couette flow to explore key parameters. Validated by 177 particle-based coarse-grain simulations, this theory indicates that the chance of successful pairing events between molecular markers and its corresponding targets—or hits—is determined by their concentrations, binding affinity or energy, and more importantly the flow velocity. Scaled collision theory reveals great potential to be used as a system design tool for a wide spectrum of sensing applications, ranging from water and air quality monitoring to biomedical detection and disease diagnostics.