Submicrometer Cavity Surface Plasmon Sensors

Abstract

A miniaturized spherical surface plasmon sensor for measuring the binding kinetics of unlabeled molecules is introduced. The sensor has a submicrometer footprint with a sensitivity that rivals that of state-of-the-art commercial planar surface plasmon sensors, which makes it valuable for applications requiring integration of detection of molecular species in microfluidic channels. The basic principle of the sensor is exploiting the wavelength shifts of the cavity resonances of a metal-coated submicrometer sphere embedded in an opaque metal film due to molecular adsorption. The sensor has been found to be exquisitely responsive in air to water and ethanol vapor adsorption on the bare gold sensor surface. When immersed in a liquid, the sensor can detect the adsorption of less than one monolayer of dodecanethiol (∼1.5 nm) on the gold coating of the sphere.

Label-Free Microcavity Biosensors: Steps towards Personalized Medicine

“…When excited with non-polarized white light perpendicular to the glass substrate (Figure 3) the microsensor emits light with a characteristic spectrum dominated by peaks, or microcavity resonances , with widths sometimes as narrow as 15 nm [105]. When excited with monochromatic light, the microcavity emission wavelength is the same as the excitation wavelength, with an amplitude depending on the microcavity resonance strength at that wavelength.…”

“…When excited with monochromatic light, the microcavity emission wavelength is the same as the excitation wavelength, with an amplitude depending on the microcavity resonance strength at that wavelength. Refractive index changes in the solution above the microsensor and biomolecular interactions at the microsensor surface change the microcavity resonance widths, strengths and center frequencies [105]. …”

“…The microsensor’s emission spectrum has characteristic spectral peaks ( microcavity resonances ) generated by surface plasmon (SP) waves confined to a gold cavity wrapped around a sub-micron dielectric sphere [105,106]. These microsensors have a number of advantages compared to the technologies we have just discussed.…”

Surface plasmon resonance enhanced coupling to whispering-gallery modes in optical micropillar resonators

“…Recently, surface plasmon resonance (SPR) [1] enhanced optical phenomena have been attracting considerable interest in a wide range of applications including biochemical sensing [2,3] and microscopy. Here we report initial experimental demonstrations of SPR enhanced coupling to whispering-gallery modes (WGMs) in silica micropillar resonators.…”

“…Here we report initial experimental demonstrations of SPR enhanced coupling to whispering-gallery modes (WGMs) in silica micropillar resonators. Compared with microsphere resonators, micropillar resonators offer a long mm-cm length for coating with biochemical molecules for SPR-enhanced sensing [2]. Fig.…”