Ultra-compact Biosensor Research Articles

Ultracompact biosensor based on a metalens with a longitudinally structured vector beam.

The refractive index is one of the essential parameters in describing biochemical reactions and biomedical diagnostics, and in situ measurement of the refractive index is very important for the micro total analysis system. We proposed an ultracompact biosensor based on a high numerical aperture metalens that was designed as two parts for generating the Pancharatnam-Berry phase and propagation phase, respectively, by using zinc sulfide nanofins, and nanopillars. Then incident light was modulated into a right-circularly polarized vortex beam and a left-circularly polarized vortex beam in the focal spot. The superposition of both beams can generate a structured vector beam with various polarization states along the focus direction. The polarization is sensitive to the difference of optical path, which has a potential application in index detection and biochemical analysis.

An optofluidic metasurface for lateral flow-through detection of breast cancer biomarker

The rapid growth of point-of-care tests demands for biosensors with high sensitivity and small size. This paper demonstrates an optofluidic metasurface that combines silicon-on-insulator (SOI) nanophotonics and nanofluidics to realize a high-performance, lateral flow-through biosensor. The metasurface is made of a periodic array of silicon nanoposts on an SOI substrate, and functionalized with specific receptor molecules. Bonding of a polydimethylsiloxane slab directly onto the surface results in an ultracompact biosensor, where analyte solutions are restricted to flow only in the space between the nanoposts. No flow exists above the nanoposts. This sensor design overcomes the issue with diffusion-limited detection of many other biosensors. The lateral flow-through feature, in conjunction with high-Q resonance modes associated with optical bound states of the metasurface, offers an improved sensitivity to subtle molecule-bonding induced changes in refractive index. The device exhibits a resonance mode around 1550 nm wavelength and provides an index sensitivity of 720 nm/RIU. Biosensing is conducted to detect the epidermal growth factor receptor 2 (ErbB2), a protein biomarker for early-stage breast cancer screening, by monitoring resonance wavelength shifts in response to specific analyte-ligand binding events at the metasurface. The limit of detection of the device is 0.7 ng mL−1 for ErbB2.

Design of grating couplers and MMI couplers on the TriPleX platform enabling ultra-compact photonic-based biosensors

We present the design of a novel photonic chip for a biosensor for food analysis, which is based on arrayed micro-ring resonators (MRRs) on the TriPleX platform. The novelty of the photonic chip lies on the fact that it eliminates the need for fiber pigtails and external polarization control and enables ultra-compact implementations by virtue of the hybrid integration of the laser source and the photodetectors on-chip. We present the MRR-based sensing mechanism, and we explain the associated power budget limitations that are particularly present in a fully integrated and arrayed version of this type of sensor. We then present in detail the simulations for the design of the grating coupler that couples the light from the flip-chip bonded laser source into the TriPleX platform and the multi-mode interference (MMI) coupler that splits the optical power among the eight parallel MRRs. We show that we can achieve a grating coupler with coupling efficiency close to 30% and an MMI coupler with insertion loss and power imbalance below 0.5dB. We finally explain why this performance is sufficient in terms of available power budget on-chip for the proper operation of the novel ultra-compact biosensor.

光子晶体微腔生化传感器的研究

The ultra-compact biosensor based on the two-dimensional (2D) photonic crystal (PhC) microcavity is investigated. The performances of the sensor are analyzed theoretically using the Fabry-Perot (F-P) cavity model and simulated using the finite-difference time-domain (FDTD) method. The simulation results go along with the theoretical analysis.

Full-field photonic biosensors based on tunable bio-doped sol–gel glasses

A full-field generic photonic biosensor approach, which relies on a bio-doped polymeric strip waveguide configuration, is described. We show the potential of tailor-made hybrid polymeric materials prepared by sol-gel technology for the fabrication of ultra-compact biosensor devices, where both the transducer and the recognition elements are merged into one single microstructure. Such devices were fabricated by micromolding in capillaries (MIMIC) soft lithographic technique. In contrast to evanescent field sensors, the sensor response does not only rely on the interaction of the evanescent wave with the recognition element, but on the interaction of the whole field, thus enabling a reduction of the sensor dimensions and/or a decrease of its limit of detection (LOD). The potential of this generic approach was demonstrated by developing a biosensor for the detection of H(2)O(2) using horseradish peroxidase (HRP) as the doping agent. Solutions containing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) and different concentrations of H(2)O(2) were dispensed over the waveguide and the green-coloured cation radical ABTS*(+) product was mainly obtained inside the photonic structure, resulting in a maximum absorption increase of 2.5 a.u. at a set working wavelength of 670 nm over the H(2)O(2) concentration range studied. The sensor exhibited a sensitivity of (3.1+/-0.2) x 10(3) a.u./mol L(-1) and a limit of detection (LOD) of 4.4 x 10(-5) mol L(-1) H(2)O(2). These results anticipate that full-field waveguide microstructures based on bio-doped sol-gel polymers will enable the fabrication of cost-effective photonic biosensors. Moreover, the ease of fabrication by a soft lithography technique and the use of such polymeric materials are fully compatible with their integration in compact automatic analysis systems.