Comparison between Vernier-cascade and MZI as transducer for biosensing with on-chip spectral filter

The Mach-Zehnder interferometer (MZI) and the Vernier-cascade are highly responsive photonic sensors with large design freedom. They are therefore very suitable for interrogation through a broadband source and an on-chip spectral filter, a sensing scheme that is well equipped for point-of-care applications. In this work, the MZI is shown to outperform the Vernier-cascade through a better minimum detectable wavelength shift as well as a higher power efficiency, indicating its superiority in this sensing scheme. Fabricated MZIs yield bulk detection limits down to 8.8 x 10(-7) refractive index units (RIU) in a point-of-care compatible measuring setup, indicating the potential of the proposed sensing scheme

Digital microfluidics with pressure-based actuation

One of the key issues in biosensors is the time it takes for biomolecules in a solution to reach and bind to the sensor surface (particularly in low-concentration analytes). We present a novel flow scheme without microfluidic channels for label-free biosensors to decrease the delivery time of biomolecules. Through designing the biosensor in such a way that it becomes a membrane with holes, we can apply a droplet on it and push or pull it through the membrane by means of a pressure difference. Contrary to traditional microfluidics for, e.g., flow cells where the analyte flows over the sensor, the flow is now directed through the sensor. We have implemented this scheme in silicon-on-insulator biosensors and have demonstrated in a first proof-of-principle experiment, an improvement in delivery time of at least a factor of three

Photonic crystal biosensor in spatial fourier domain

We propose a photonic crystal biosensor, operating at a single wavelength, based on analysis of resonant guided modes in the spatial Fourier domain. Sensitivities of 65 degrees per RIU and more have been simulated

The complex Jacobi iterative method for non-paraxial beam propagation in nonlinear optical waveguides

The recently introduced beam propagation method using complex Jacobi iteration adapted for modeling of non-paraxial beam propagation in nonlinear optical waveguides is presented in this paper. The beam propagation equation is based on our recently proposed modified Pad,(1,1) approximant operator. The resulting approach is very efficient and well-suited for large structures with long propagation paths