Porous silicon platform for optical detection of functionalized magnetic particles biosensing.

The physical properties of porous materials are being exploited for a wide range of applications including optical biosensors, waveguides, gas sensors, micro capacitors, and solar cells. Here, we review the fast, easy and inexpensive electrochemical anodization based fabrication porous silicon (PSi) for optical biosensing using functionalized magnetic particles. Combining magnetically labeled biomolecules with PSi offers a rapid and one-step immunoassay and real-time detection by magnetic manipulation of superparamagnetic beads (SPBs) functionalized with target molecules onto corresponding probe molecules immobilized inside nano-pores of PSi. We first give an introduction to electrochemical and chemical etching procedures used to fabricate a wide range of PSi structures. Next, we describe the basic properties of PSi and underlying optical scattering mechanisms that govern their unique optical properties. Finally, we give examples of our experiments that demonstrate the potential of combining PSi and magnetic beads for real-time point of care diagnostics.