Handheld high-throughput plasmonic biosensor using computational on-chip imaging

We demonstrate a handheld on-chip biosensing technology that employs plasmonic microarrays coupled with a lens-free computational imaging system towards multiplexed and high-throughput screening of biomolecular interactions for point-of-care applications and resource-limited settings. This lightweight and field-portable biosensing device, weighing 60 g and 7.5 cm tall, utilizes a compact optoelectronic sensor array to record the diffraction patterns of plasmonic nanostructures under uniform illumination by a single-light emitting diode tuned to the plasmonic mode of the nanoapertures. Employing a sensitive plasmonic array design that is combined with lens-free computational imaging, we demonstrate label-free and quantitative detection of biomolecules with a protein layer thickness down to 3 nm. Integrating large-scale plasmonic microarrays, our on-chip imaging platform enables simultaneous detection of protein mono- and bilayers on the same platform over a wide range of biomolecule concentrations. In this handheld device, we also employ an iterative phase retrieval-based image reconstruction method, which offers the ability to digitally image a highly multiplexed array of sensors on the same plasmonic chip, making this approach especially suitable for high-throughput diagnostic applications in field settings. A handheld biosensor that employs lens-free imaging on a plasmonic chip could simplify high-throughput protein detection. The device, developed by Arif Cetin and co-workers at Boston University and the University of California at Los Angeles in the USA, promises label-free quantitative detection of large variety of proteins on the same sensor chip. The unit, which is battery-powered, 7.5 cm tall and just 60 g in weight, operates by transmitting light from an LED through a functionalized plasmonic chip containing an array of periodic nanoholes in a gold film. The diffraction pattern of the nanoapertures is recorded by a CMOS image sensor. The presence of a protein monolayer as thin as 3 nm that binds to the plasmonic chip induces a dramatic change in the diffraction pattern sampled by the image sensor chip.