Enhancing the Sensitivity of Label-Free Silicon Photonic Biosensors through Increased Probe Molecule Density

Abstract

We report a greater than 5-fold increase in the detection sensitivity and a greater than 3-fold reduction in the response time of planar silicon photonic biosensors by increasing the density of probe molecules through the use of an in situ probe synthesis approach. DNA probe molecules are grown in a base-by-base manner with the desired sequence on silicon ring resonator and photonic crystal biosensors, resulting in a greater than 5-fold increase in surface area coverage compared to traditional covalent conjugation methods. With this approach, we demonstrate enhanced light–matter interaction, reduced optofluidic assay detection times, increased transduced signal sensitivity, and improved immunity toward false positives. This work highlights the importance of improving bioreceptor surface coverage densities in low mode volume photonic crystal devices and micrometer-scale ring resonators as a means of mitigating the effects of shrinking device sizes that otherwise limit the number of available target molecul...