Fig. 2: STR sensing process at the nanoscale. | npj Biosensing

Fig. 2: STR sensing process at the nanoscale.

From: Surface Transmon Resonance (STR): a handheld nanogap biosensor for real-time, label-free molecular binding kinetics

Fig. 2

The light blue arrow indicates the flow of the solution. A shows the sensing region before any binding occurs; Overlaid COMSOL simulation (at 150 MHz) shows electric field confinement in the nanogap region. B Injection of bovine serum albumin (BSA), which adsorbs to gold surfaces inside the nanogap. C Introduction of anti-BSA antibodies, which selectively bind to surface-adsorbed BSA. D Buffer is reintroduced to wash out unbound antibodies, allowing dissociation dynamics to be monitored. E Accumulation of molecules inside the nanogap perturbs local permittivity, shifting the resonant frequency. F Real-time tracking of resonance frequency shift captures kinetic binding curves over the measurement period.

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