A grating coupled porous silicon (pSi) Bloch Surface Wave (BSW) biosensor capable of supporting a surface mode is demonstrated for the real-time detection of both small and large molecules. In contrast to most pSi based sensor platforms that are unable to perform high sensitivity detection of large molecules that do not infiltrate into the porous matrix, the pSi BSW sensor has more than 15% of the field intensity confined to the surface of the structure, allowing for high sensitivity detection of surface-bound large molecules. Angular interrogated reflectance measurements were carried out to benchmark the performance of the pSi BSW against two common pSi sensor platforms, the waveguide and microcavity, after exposing each sensor to two different small molecules and one large molecule in a flow-cell environment. All of the sensors showed comparable sensitivity towards the detection of the small molecules, but the BSW sensor was clearly superior for detection of the large molecules. The experimental results were found to be in good agreement with simulations based on rigorous coupled wave analysis and the transfer matrix method.
In this work, we theoretically and experimentally demonstrate a highly sensitive polymer-cladded porous silicon (PSi)
membrane waveguide based on a ~1.55 μm thick porous silicon membrane coated on one side with a low loss polymer.
The sensor operates in the Kretschmann configuration, which is amenable to microfluidics integration, with a high index
cubic zirconium prism. The sensitivity of the sensor is investigated through PNA hybridization in the PSi membrane. We
demonstrate that higher angle resonances and a proper ratio of PNA length to PSi pore diameter lead to significantly
improved detection sensitivity. A detection sensitivity below 0.1°/μM is reported for 16mer target PNA. Calculations
and complimentary experiments show that careful tuning of the polymer cladding thickness can further improve the
In this work, we theoretically and experimentally demonstrate a highly sensitive porous silicon membrane
waveguide biosensor in the Kretschmann configuration, and show how the cladding material directly impacts
the waveguide sensor detection sensitivity and resonance width. Dielectric and metal-clad porous waveguides in
the Kretchmann configuration have the potential to achieve significantly enhanced performance for small
molecule detection compared to planar waveguide and surface plasmon resonance sensors due to increased
surface area and strong field confinement in the porous waveguide layer. First order perturbation theory
calculations predict that the quality factors of polymer-cladded porous silicon waveguides with porous silicon
losses less than ~500 dB/cm are at least two times larger than the quality factors of gold-cladded porous silicon
waveguides and traditional surface plasmon resonance sensors.