We report an experimental demonstration of an integrated biochemical sensor based on a slot-waveguide microring resonator. The microresonator is fabricated on a Si3N4-SiO2 platform and operates at a wavelength of 1.3 microm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n=1.33 to 1.42. A linear shift of the resonant wavelength with increasing ambient refractive index of 212 nm/refractive index units (RIU) is observed. The sensor detects a minimal refractive index variation of 2x10(-4) RIU.

We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 x 10(-6) refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm(-2), to our knowledge the best reported values for integrated planar ring resonators.

QC 20100715

We demonstrate label-free molecule detection by using an integrated biosensor based on a Si 3 N4/Si0 2 slotwaveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm 2 ) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm 2 for anti-BSA and BSA, respectively, limited by wavelength resolution.Label-free biomolecule optical sensing technologies are of great interest because of their flexibility to analyze biomolecular interactions without using fluorescence, absorptive, or radio-labels. This simplifies the assay and allows time-resolved study of the kinetics of biomolecular interactions. Integrated photonic devices used as biosensors present important advantages, such as high sensitivity, small size, and high scale integration. Thus, label-free integrated optical biosensors based on Mach-Zehnder interferometers , directional couplers , microring , and disk resonators have been demonstrated to be very sensitive label-free biosensors.Recently, we have reported an integrated photonic sensor based on a slot-waveguide resonator . This photonic structure takes advantage of the remarkable property of slot-waveguides to provide high optical intensity in a subwavelength-size low refractive index region (slot-region) sandwiched between two high refractive index strips (rails) . This permits a very high interaction between the slot-waveguide mode probe and a liquid analyte. As a result, the reported slot-waveguide sensor exhibited a bulk ambient sensitivity as high as 212.1 nm/refractive index unit (RIU), which is more than twice as large as that exhibited by ring resonator optical sensors based on conventional strip waveguides. In this Letter we demonstrate the detection of label-free molecular binding reactions on the surface of a slot-waveguide ring resonator. Bovine serum albumin (BSA) protein and anti-BSA are used to study the biosensor performance.The device consists of a 70 /mm radius slotwaveguide ring resonator made of Si 3 N 4 on Si0 2 The Si 3 N4 rails of the slot-waveguide ring are separated by 200 nm (w sht ), and their widths are 400 and 550 nm for the outer and inner rails, respectively, as illustrated in Fig. 1(a). A beam propagation method calculation of the quasi-TE optical mode of the ring slot-waveguide at 1.3 /mm operation wavelength is

Integrating two-dimensional (2D) materials into semiconductor manufacturing lines is essential to exploit their material properties in a wide range of application areas. However, current approaches are not compatible with high-volume manufacturing on wafer level. Here, we report a generic methodology for large-area integration of 2D materials by adhesive wafer bonding. Our approach avoids manual handling and uses equipment, processes, and materials that are readily available in large-scale semiconductor manufacturing lines. We demonstrate the transfer of CVD graphene from copper foils (100-mm diameter) and molybdenum disulfide (MoS2) from SiO2/Si chips (centimeter-sized) to silicon wafers (100-mm diameter). Furthermore, we stack graphene with CVD hexagonal boron nitride and MoS2 layers to heterostructures, and fabricate encapsulated field-effect graphene devices, with high carrier mobilities of up to $$4520\;{\mathrm{cm}}^2{\mathrm{V}}^{ - 1}{\mathrm{s}}^{ - 1}$$ 4520 cm 2 V − 1 s − 1 . Thus, our approach is suited for backend of the line integration of 2D materials on top of integrated circuits, with potential to accelerate progress in electronics, photonics, and sensing.

This is the accepted version of a paper published in. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.

We present an experimental study of an integrated slot-waveguide refractive index sensor array fabricated in silicon nitride on silica. We study the temperature dependence of the slot-waveguide ring resonator sensors and find that they show a low temperature dependence of -16.6 pm/K, while at the same time a large refractive index sensitivity of 240 nm per refractive index unit. Furthermore, by using on-chip temperature referencing, a differential temperature sensitivity of only 0.3 pm/K is obtained, without individual sensor calibration. This low value indicates good sensor-to-sensor repeatability, thus enabling use in highly parallel chemical assays. We demonstrate refractive index measurements during temperature drift and show a detection limit of 8.8 x 10-6 refractive index units in a 7 K temperature operating window, without external temperature control. Finally, we suggest the possibility of athermal slot-waveguide sensor design.

We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of <20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.

Optofluidics, nominally the research area where optics and fluidics merge, is a relatively new research field and it is only in the last decade that there has been a large increase in the number of optofluidics applications as well as in the number of research groups devoted to the topic. Nowadays optofluidics applications include, without being limited to, lab-on-chip devices, fluid-based and controlled lenses, optical sensors for fluids and for suspended particles, biosensors, imaging tools, etc. The long list of potential optofluidics applications, which have been recently demonstrated, suggests that optofluidic technologies will become more and more common in everyday life in the future, causing a significant impact on many aspects of our society. A characteristic of this research field, deriving from both its inter-disciplinary origin and applications, is that in order to develop suitable solutions it is often required to combine a deep knowledge in different fields, ranging from materials science to photonics, from microfluidics to molecular biology and biophysics. As a direct consequence, also being able to understand the long-term evolution of optofluidics research is not an easy target. In this article we report several expert-contributions on different topics, so as to provide guidance for young scientists. At the same time we hope that this document will also prove useful for funding institutions and stake holders, to better understand the perspectives and opportunities offered by this research field.