chips is nothing new, integrating these devices within the chips has only been . and B. Eggleton, “Integrated optofluidics: A new river of light,”. C. Monat, P. Domachuk and B. J. Eggleton, “Integrated Optofluidics A New River of Light,” Nature Photonics, Vol. 1, No. 2, , pp. Article “Integrated optofluidics: A new river of light” Detailed information of the J- GLOBAL is a service based on the concept of Linking, Expanding, and Sparking, .
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Skip to main content. Log In Sign Up. A new river of light. A new river of light The realization of miniaturized optofluidic platforms offers potential for achieving more functional and more compact devices.
Integrated optofluidics: A new river of light – Dimensions
Such integrated systems bring fluid and light together and exploit their microscale interaction for a large variety of applications. The high sensitivity of compact microphotonic devices can generate effective microfluidic sensors, with integration capabilities. By turning the technology around, the exploitation of fluid properties holds the promise of highly flexible, tunable or reconfigurable microphotonic devices. We overview some of the exciting developments so far.
Optofluidics fundamentally aims at manipulating fluids and light Applications have been found in clinical analysis, drug discovery at the microscale and exploiting their interaction to create highly and small-volume DNA replication and testing13, The analytical versatile systems.
The integration their functionality1,2, a wide variety of optofluidic devices have x monolithic or hybrid optical and optoelectronic devices light also recently been demonstrated3. Combining fluids and light has sources, filters or photodetectors into the lab-on-a-chip15—18 is produced all sorts optofluidcis creative devices, such as adaptive optical being investigated at nrw to improve the performance and lenses4,5 or optofluidic microscopes6. Further opportunities were portability of these systems1,2.
In the context of circuit lacks at the micrometre scale: In this respect, microfluidics has some unique to be analysed through highly sensitive microphotonic circuits. Microfluidic laminar flows can efficiently transport Conversely, microfluids can be exploited to control microphotonic various species or nanostructures with desirable optical properties.
Those species that are otherwise difficult to handle can be brought Photonics has evolved towards device miniaturization with the into targeted locations of a microphotonic circuit. Microfluidics also ultimate goal of integrating many optical components onto a compact offers a wealth of ways to control microphotonic devices. The range of chip, producing photonic integrated circuits with low cost and high index modulation achievable through fluid manipulation is very large degrees of functionality.
Planar photonic crystals7, formed from periodic and can be induced locally using microfluidic circuitry.
Because of the lattices of submicrometre air holes inscribed in a slab nea, mobile nature of the fluid phase, it can be used as a changeable part provide a generic platform to realize photonic integrated circuits8. Liquid—liquid The generation of microstructured optical fibres with micrometre- L2 and liquid—air flexible interfaces can produce highly adaptive sized air voids9,10 and the capability of tapering aa also offer new optofluidic devices.
Eventually, microfluidics will provide unique opportunities to achieve miniaturized optical functions. Nonetheless, means to exploit the specific behaviour of fluids that are confined at control systems should be developed simultaneously to operate such the microscale Box 1.
We first review a new class of optofluidic light properties of a photonic circuit through substantial and local variations sources. Second, we demonstrate how the high sensitivity of integrated in the refractive index, n. As the spatial scale is reduced in microscopic microphotonic devices can generate effective and miniaturized fluidic devices, the necessary range of index modulation becomes higher and sensors.
The last range of applications relies on the use of microfluids to more challenging to achieve. For instance, loght a tunability range of control, tune and reconfigure optical microdevices.
Since the s, microfluidics has been the subject of Microdevices, for example MEMS, are traditionally fabricated fo concerted research efforts both in academic institutions and silicon or silica, using the well-established micromachining process nature photonics VOL 1 FEBRUARY www.
Although numerous microfluidic systems have been built from those techniques and materials, more recently Box 1 The physics of microfluidics alternative cheaper processes, using low-cost polymeric materials such as polydimethylsiloxane PDMS or polymethylmethacrylate The dynamics of fluids on nrw microscale obey the governing PMMAhave been developed. PDMS has attractive properties equations of fluids on the macroscale — the Navier—Stokes such as elasticity, optical transparency ndw a biocompatible surface equations.
However, microflows exhibit characteristic behaviours chemistry For flows confined or adaptive lenses Soft over inertial forces and the flow has damping nonlinearity.
This mould can then replicate many identical devices flow — a lack of turbulent flow means that all mixing is driven easily, owing to the low surface affinity of PDMS that allows it to by diffusion of the species, providing design challenges in be easily detached.
Resolution is limited only by the fidelity of the making microfluidic mixers that produce homogenous output mould23; rapidity and economy are possible by restricting complex in a compact space.
Capillarity phenomena play a major role on the Various microfluidic components, such as micromechanical micrometre scale. The surface tension at the phase boundary valves20, microchannels, micropumps24, microfluidic mixers25 and of a fluid dominates over the viscous forces inside the fluid. Their large-scale integration27 onto one chip micrometre scale, by several orders of magnitude. It can be allows for the construction of compact functional microfluidic used to introduce a fluid into a void but similarly renders the platforms Microfluidic systems can perform multiple same fluid difficult to remove.
However, these effects may also be used to create fabricated from the same materials using the same processes, structures such as L2 waveguides or highly efficient actuation potentially during the same fabrication step; or they can be mechanisms electro-wetting.
Indeed, the nature and fabricated separately and post-assembled2. However, despite recent engineering of these effects is a topic of ongoing research in demonstrations30—32, complete integration of both complex platforms fundamental microfluidics.
Exploration of optofluidic functionality is the aim of most current investigation.
J-GLOBAL – Japan Science and Technology Agency
The following three sections highlight some examples of developing techniques and devices derived from this research. An alternative process based on nanoimprinted thermoplastic has been successfully Typical biochemical analysis relies on bulky, costly and lossy free- developed The technique involves a high-resolution silicon space optics carefully coupled through a microfluidic system.
Integrated optofluidics could provide photonic integration for Li et al. Integrwted this context, integrated, planar light polymer stamp The laser maintains single-mode operation while sources are essential. These devices Another class of microfluidic light sources relies on L2 waveguides, use active species dissolved in a liquid solution as the gain medium.
The range are commercially available. Light microfluidic channels to specific locations where the active medium emission, collection and propagation all occur within the liquid dye will efficiently interact with the optical modes of the device; dye core. These devices possess a high degree of flexibility enabled by bleaching effects are avoided by regenerating a continuous flow of the dynamic control of the optical and geometrical properties of the dyes through the laser cavity; and most importantly, unlike their liquid core and cladding.
The emission wavelength can be tuned by solid-state counterparts, liquid dye lasers are inherently tunable. The output beam size Since the first demonstration33 inmicrofluidic light and intensity are changed by the manipulation if the liquid flow sources have progressed in terms of functionality, compactness rates Eventually, L2 waveguides with different dye molecules can and manufacturing.
By have been explored.
The microring-based lasers have a switchable achieved with equally good ligbt, Note that these lasers output coupled into an integrated polymer waveguide but are are still not stand-alone devices because they usually rely on: The distributed-feedback microlasers display an external gas pressure source to ensure a microfluidic continuous narrowband laser operation by exploiting antiguiding effects and are flow; and 2 free-space external pumping lasers. Changing the dye molecules, the solvent, the dye concentration or the liquid flow rates are all different ways to tune these od.
This is possible by integrating microvalves, Output micropumps, and mixers30, This integrated microfluidic system involved a closed-loop-based mixer and a micropump to adjust the concentration of the nanolitre dye solution and the flow rate. This provides the continuous tuning of both the laser wavelength over 8 nm and the intensity. Eventually, additional devices may be integrated to increase the degree of functionality of optifluidics optofluidic platform A wide variety of optical methods have been used for biochemical 20 sensing, such as absorbance, fluorescence, Raman-scattering, refraction or surface-plasmon-resonance measurements.
Integrated 10 optics can be successfully combined with all these schemes2,47, bringing the unique advantages associated to its planar format. In particular, it has proved useful for directly exciting48 or collecting49 0 or both50,51 particle fluorescence, improving the limit of detection 0 10 20 optofluidice 40 and reducing the probed volumes Reference 47 presents a comprehensive Intensity a.
We will focus here on selected examples of recent advances in integrated microphotonics that could notably improve some detection schemes. Some sensors involve evanescent coupling: Other sensors exhibit direct coupling: The degree of the Wavelength nm interaction strongly determines the device sensitivity.
Optocluidics increasing the optical pathlength represents one if to raise the light—fluid interaction, many integrated optical Figure 1 Optofluidic laser.
A similar trend is obtained for couplers that exploit spectrum. Reproduced with permission from ref. Hollow-core antiresonant reflecting optical waveguides ARROWs benefit from a high sensitivity owing to the direct interaction between fluids and light as they are could be addressed by using emerging integrated techniques to both guided inside the waveguide core51, However, the waveguide actuate microfluids see below.
Regarding the second issue, an length should be large enough about 2 cm to collect substantial internal pumping configuration, in which the pump beam is guided signal modulations Optical waveguides have also been combined to the chip intefrated an optical fibre, is also possible They rely on the selective Liquid-dye microlasers can be tuned by manipulating the coupling between a dielectric waveguide and a leaky metal-coated cavity conditions using, for instance, elastomer to construct the waveguide.
Scanning electron micrographs of various microcavities, which can be used as effective biosensors owing to their low optical losses and high compactness. Absorbance, Raman or interface extends far into the surrounding liquid. However, relatively fluorescence schemes, whose sensitivities are proportional to the high interaction lengths 1. Resonant optical in recent years Fig. Furthermore, input and output ports. Silicon microdisks with intensity of the analytes63, improving the respective signals of moderate Q about 5, have enabled the detection of fluid fluorescence and absorbance detection methods.
The resulting high index variations down to 10—4 for 10 femtolitres surrounding sensitivities on compact areas reduce the limit of detection, in terms fluid volume Indeed, optofluidicd device to detect lighht differences in the water absorption Beam path Bragg gratings provide another kind of resonator structure channel with sensing capabilities: Despite their good performance, the sensitivity of the above microresonators and more generally of evanescent-wave sensitive devices is intrinsically limited by the restriction of the fluid—light b Planar integration interaction over the short penetration depth of light in the fluid about a wavelengthat the device surface.
Having the analysed Microfluidic solution directly located inside the optical resonator should provide channel Single-mode fibre more efficient sensors.
This can be achieved through interference effects, as involved in hollow ARROWs or integraetd structures. Planar photonic-crystal cavities c can be engineered to concentrate light in their nanometre-sized air pores, where analytes can be directly introduced. Slot waveguides82, which consist of —12 two close and parallel waveguides, represent another innovative Transmission dB geometry to maximize the overlap between light and fluids.
Arrays of —20 waveguides can provide multipoint detection47,2, possibly useful for single-particle detection