Sensitivity‐enhancement methods for surface plasmon sensors

Abstract

Surface plasmon resonance (SPR) sensors have been a mature technology for more than two decades now, however, recent investigations show continuous enhancement of their sensitivity and their lower detection limit. Together with the recent investigations in localized SPR phenomena, extraordinary optical transmission through nanoapertures in metals, and surface-enhanced spectroscopies, drastic developments are expected to revolutionize the field of optical biosensing. Sensitivity-enhancement (SE) techniques are reviewed focusing both on the physical transduction mechanisms and the system performance. In the majority of cases the SE is associated with the enhancement of the electromagnetic field overlap integral describing the interaction energy within the analyte. Other important mechanisms are the interaction between plasmons and excitons and between the analyte molecules and the metal surface. The lower detection limit can be reduced significantly if systems with high signal-to-noise ratio are used such as common-path interferometry, ellipsometry or polarimetry systems.

Lasing Enhanced Surface Plasmon Resonance Sensing

“…Surface plasmon sensors operate on the principle that small changes in refractive index at the vicinity of metal surface can result in a shift of surface plasmon resonance, which can be detected at optical far field, allowing non-contact, realtime and label-free sensing and detection [2][3][4][5][6]. In the past two decades, the surface plasmon resonance (SPR) sensors based on propagating surface plasmon polaritons have become a prominent tool for characterising and quantifying biomolecular interactions and are perhaps the most extensively utilised optical biosensors [3,7,8]. However, the propagating surface plasmons on flat surface cannot be directly excited due to their large momentum.…”

“…However, the propagating surface plasmons on flat surface cannot be directly excited due to their large momentum. In most SPR sensors, the Kretschmann configuration of attenuated total reflection is used to excite surface plasmons, which requires precise adjustment of the incident angle of the probing radiation [3,7,8]. Therefore, it remains a challenge for SPR sensors to have point-of-care performance and satisfy modern nanobiotechnology architectures [3,7,9].…”

Optimized Dielectric Film for Maximum Sensitivity of Nearly Guided‐Wave Surface Plasmon Resonance Sensor

“…[19] In Figure 4, we plot the reflectivity curves as a function of incident angle for NGWSPR sensors with optimal thickness of Si, AlAs, TiO 2 , and Si 3 N 4 film. Four reflectance curves all exhibit low depth of dip (R res < 10%), which indicates high SNR of optimized NGWSPR sensors.…”

“…Although it has been demonstrated that under the condition of the same thickness of the dielectric film a NGWSPR sensor with a higher refractive index dielectric film can achieve higher sensitivity, [15,19] it is still doubtful whether the dielectric film with higher refractive index is more beneficial for the sensitivity improvement, because the sensitivity of a NGWSPR sensor can be further improved by optimizing the thickness of the dielectric film. [20] So, to achieve the maximum sensitivity for a NGWSPR sensor, the material (or refractive index) and the thickness of the top dielectric film need to be optimized simultaneously, which has not been studied until now.…”

Enhancing sensitivity of SPR sensors by using nanostructured Au chips coated with functional plasma polymer nanofilms

“…Even though SPR biosensors are more sensitive than other label-free devices, they are still unable to achieve the direct detection of small molecular species (a few hundreds of Daltons). Consequently, various proposals have been developed to enhance the sensitivity or resolution of biosensors [8,9].…”