Optical and Electrochemical Biosensors Using Electrochemically Etched Porous Silicon

Versatile nanostructured materials based on electrochemically etched porous silicon (pSi) are being developed, which have tuneable pore morphology and unique optical and electrochemical properties that enable their effective biosensing applications. It has been shown that fabrication parameters critically influence pore formation and sensor performance, yet challenges remain in reproducible synthesis, structural stability and device integration. Here we review the electrochemical etching synthesis of pSi and recent advances in pSi-based optical and electrochemical biosensors for detecting bacteria, biomolecules, and viruses. We highlight strategies such as surface functionalisation, incorporation of nanomaterials, and integration with microfluidic and lab-on-a-chip technologies that enhance sensitivity and response times by addressing mass transfer limitations. These developments highlight pSi's potential as a low-cost, adaptable biosensing material with applications in clinical diagnostics and environmental monitoring, while mapping future directions to overcome current fabrication and stability challenges.