Biosensing using straight long-range surface plasmon waveguides

Abstract

Straight long-range surface plasmon waveguides are demonstrated as biosensors for the detection of cells, proteins and changes in the bulk refractive index of solutions. The sensors consist of 5 μm wide 22 nm thick Au stripes embedded in polymer (CYTOP™) with microfluidic channels etched into the top cladding. Bulk sensing is demonstrated by sequentially injecting six solutions of different refractive indices in 2 × 10(-3) RIU increments; such index steps were detected with a signal-to-noise ratio of ~1000. Selective capture of cells is demonstrated using Au waveguides functionalized with antibodies against blood group A, and red blood cells of group A and O in buffer as positive and negative analyte. Bovine serum albumin in buffer was used to demonstrate protein sensing. A monolayer of bovine serum albumin physisorbed on a carboxyl-terminated self-assembled monolayer on Au was detected with a signal-to-noise ratio of ~300. Overall, the biosensor demonstrated a good capability for detecting bulk changes in solution and for sensing analyte over a very wide range of mass (from cells to proteins). The biosensors are compact, inexpensive to fabricate, and may find use over a wide range of cost-sensitive sensing and detection applications.

Experimental demonstration of titanium nitride plasmonic interconnects

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Histogram analysis for smartphone-based rapid hematocrit determination

“…In microfluidic platforms for various point-of-care testings (POCTs), a number of opticaldetection techniques have already been demonstrated including absorbance [10,11], surfaceplasmon resonance [12,13], high-resolution near-field and far-field fluorescence, and chemiluminescence methods [14][15][16]. While these methods include the advantage of a minimal sample preparation for the provision of a real-time detection, they are excessively expensive and highly trained technical personnel with the necessary laboratory setup are required [17,18].…”

Nonlinear effects in propagation of long-range surface plasmon polaritons in gold strip waveguides

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