Low-Cost and Portable Plasmonic Biosensor for Label-Free Detection of Viruses in Resource-Limited Settings

The development of rapid diagnostic kits is very critical for the early diagnosis and treatment of infectious diseases. In this study, a lightweight and field-portable biosensor that uses a plasmonic chip based on nanohole arrays integrated into a lens-free imaging framework was presented for label-free virus detection in field settings. A high-efficiency CMOS camera was used in the biosensor platform to observe the diffraction field patterns of nanohole arrays under uniform illumination from a spectrally-tuned LED source, which is specifically configured to excite the plasmonic mode supported by the nanohole arrays. The portable biosensor presented reliable label-free detection of H1N1 viruses and produced accurate results at medically relevant concentrations. A low-cost and user-friendly sample preparation kit was developed in order to prepare the surface of the plasmonic chip for analyte binding, e.g., virus-antibody binding. A Python-based graphical user interface (GUI) was also developed to make it easy for the user to access the biosensor hardware, capture and process diffraction field images, and present virus information to the end-user. The portable biosensor platform employs nanohole arrays and lens-free imaging for highly sensitive virus detection with an LOD of 10³ TCID₅₀/mL. It is accurate and efficient, making it suitable for diagnostic use in resource-limited settings where access to advanced equipment may be limited. The presented platform technology could quickly adapt to capture and detect other different viral diseases, e.g., COVID-19 or influenza by simply coating the plasmonic chip surface with an antibody possessing affinity to the virus type of interest.