Label-Free $\hbox{Si}_{3}\hbox{N}_{4}$ Photonic Crystal Based Immunosensors for Diagnostic Applications

Immunosensors are devices that exploit immobilized antibodies to promote the binding of specific analytes related to diseases of medical importance, such as cancer or cardiac dysfunctions. Label-free immunosensors have an important role, due to their simplicity and fast read-out. Here, the proof of concept for an immunosensor based on a 2-D photonic crystal silicon nitride membrane is presented. The device has been fabricated by means of a well-tuned nanofabrication protocol, achieving a high-quality photonic pattern on a large-area membrane (1 mm $\times$ 1 mm), and it has been tested for the detection of interleukin-6, getting protein detection at pg/mL concentrations.