CN101825743A - Fluid optical waveguide structure - Google Patents

Abstract

The invention discloses a structure of a fluid optical waveguide, which is based on the principle that the refractive index of the fluid changes with temperature, and adopts an electrode heating method to form the fluid optical waveguide. Substrate I, structural layer and substrate II are sequentially included. There is a micropipe on the structural layer, and its two ends communicate with the input port 5 and the output port 7 respectively. A pair of metal electrodes are respectively located on the corresponding positions of the base I and the base II, or are located on the two inner walls of the structural layer, or cover the entire micropipe. Openings are arranged on the substrate 1 at positions corresponding to the input port 5 and the output port 7 on the structural layer. In order to ensure the insulation between the metal electrode and the fluid, a polymer film can be covered on the metal electrode. Since any same fluid can be used, the material selection of the fluid optical waveguide is more flexible; through simple circuit control, the stable propagation of light in the fluid optical waveguide is realized, which provides a simple tool for the optical detection of biological cells and biological macromolecules.

Description

Fluid optical waveguide structure

Field

The invention relates to a fluid optical waveguide structure, which belongs to the field of fluid optical waveguides in the field of micromechanical electronic systems (MEMS) and integrated optics.

current technology

Fluid optical waveguides can provide a living liquid environment for biological detection, and at the same time provide a physical channel for optical information transmission, and have been extensively studied in recent years. The structure of the fluid optical waveguide in the current research includes three types: (1) the material of the waveguide layer is fluid, and the material of the cladding layer is solid; (2) the material of the waveguide layer is fluid, and the material of the cladding layer is fluid; (3) the guide wave The layer material is a fluid and the cover layer material is a gas.

A fluidic optical waveguide composed of a fluidic waveguiding layer and a solid covering layer. A Chinese patent (CN200710044173.3) proposes a fluid optical waveguide structure composed of a fluid waveguide layer and a solid covering layer, and a fluid with a refractive index greater than that of the solid covering layer is selected so that light is fully internal in the fluid waveguiding layer. Reflection propagation; similar structures can also be found in the article published by Datta et al. on pages 788-795 of Volume 3 of IEEE SENSORS JOURNAL in 2003. Or the solid covering layer uses the interference principle to carry out light transmission. In the article published on pages 3477-3479 of APL 85 in 2004, Yin et al. proposed a fluid optical waveguide structure composed of a fluid waveguide layer and a solid covering layer. The solid The refractive index of the covering layer is greater than the refractive index of the fluid, and coherent interference in the multilayer covering layer causes interference propagation of light in the covering layer. See also Yin et al. OPTICS EXPRESS 2005 Issue 13 No. 23. Fluid optical waveguides composed of solid cladding layers must select appropriate materials or complex manufacturing processes to satisfy the condition that the refractive index of the solid cladding layer is lower than that of the fluid.

A fluidic optical waveguide composed of a fluidic waveguide layer and a gas cover layer. Yang Seung Man et al. proposed an optical waveguide composed of a fluid waveguide layer and a gas covering layer in European patent (KR20090100956).

The fluid optical waveguide composed of the fluid waveguide layer and the fluid cover layer also adopts the waveguide layer fluid whose refractive index is higher than that of the cover layer fluid, so as to satisfy the total reflection propagation of light in the fluid waveguide layer. The US patent (US2009/0097808A1) obtained by Wolfe et al. proposes a fluid optical waveguide structure with a small diffusion coefficient when the two fluids are in a laminar flow state, and a waveguide layer and a cover layer are formed by fluids with different refractive index values. Chinese patent (200680005292) proposes a fluid optical waveguide composed of two immiscible fluids with different conductivity. The fluid with a large refractive index acts as a waveguide layer. This structure can change the interface of the liquid through the electrowetting effect to Change the transmission properties of light. In their article published on APL 88, 061112 in 2006, Tang et al. described a fluidic optical waveguide structure composed of the same fluid at different temperatures. Similar structures can also be found in the article published by Li et al. on APL 93, 193901 in 2008. The fluid optical waveguide composed of a fluid covering layer affects the stable propagation of light in the fluid optical waveguide due to the diffusion of molecules between the fluids and the instability of the temperature field.

Contents of the invention

The purpose of the present invention is: for the existing fluid optical waveguide that is made of solid covering layer, the materials of solid covering layer and fluid waveguide layer are limited, and the fluid optical waveguide made of fluid covering layer is caused by the diffusion of molecules between fluids. Based on the current situation of unstable light propagation, a fluid optical waveguide structure with a simple structure that can realize stable light propagation in a fluid micropipe and its application method are proposed.

Referring to accompanying drawing 1 and accompanying drawing 2, the technical scheme of the present invention is: a kind of fluid light waveguide structure, comprises substrate I1, structural layer 2 and substrate II3 in turn, and the micropipe parallel to substrate I1 and substrate II3 is arranged on structural layer 2 , the micropipe is filled with fluid, and its two ends communicate with the input port 5 and the output port 7 respectively, and a pair of metal electrodes 4 are respectively placed on the corresponding positions on the substrate I1 and the substrate II3 to directly heat the fluid in the micropipe; the metal electrodes 4 can also be located on the two inner walls of the structural layer 2, or the metal electrode 4 covers the whole micropipe; the substrate I1 is provided with openings at positions corresponding to the input port 5 and the output port 7 on the structural layer 2, and the for fluid input and output.

In order to ensure the insulation between the metal electrode 4 and the fluid, the surface of the metal electrode 4 is covered with a polymer film 8, see Figures 7-9.

The beneficial effect of the present invention is that the fluid optical waveguide is formed based on the principle that the fluid refractive index changes with the fluid temperature. Applying a constant current to the metal electrode 4 causes the temperature of the metal electrode 4 to rise. Due to heat transfer, the temperature of the fluid region in contact with the metal electrode 4 in the micropipe increases, so that the refractive index of the fluid in this region decreases, and the fluid in the micropipe Form regions with different refractive indices, the region in contact with the metal electrode 4 constitutes the fluid covering layer 11, and the fluid region sandwiched between the fluid covering layers constitutes the fluid waveguide layer 12; There is a refractive index gradient between them, so that the light propagates stably in the fluid waveguide layer 12 .

The fluid optical waveguide structure proposed by the present invention adopts the electrode heating method at the edge of the fluid micropipe, so that the refractive index of the fluid in the contact electrode area changes to form a fluid covering layer. Using any same fluid in the micropipe to prepare the fluidic optical waveguide makes the material selection of the fluidic optical waveguide more flexible; through simple circuit control, the stable propagation of light in the fluidic optical waveguide can be realized, which is a great support for biological cells and biological macromolecules. Optical inspection provides easy tools.

Figure overview

Fig. 1 is a structural schematic diagram of a fluid optical waveguide;

FIG. 2 is a schematic cross-sectional view of the fluidic optical waveguide 6 in Embodiment 1;

Fig. 3 is the sectional view of B-B section among Fig. 2;

Fig. 4 is a graph showing the relationship between the change in the refractive index of the fluid 9 and the distance between the fluid 9 and the metal electrode 4 when a constant current is applied to the metal electrode 4;

5A-C are schematic diagrams of the relative positional relationship between the fluid waveguide layer 12 and the fluid covering layer 11 in Embodiment 1;

FIG. 6 is a schematic diagram of the beam 10 propagating in the fluidic optical waveguide 6;

Fig. 7 is a cross-sectional schematic diagram of the fluidic optical waveguide 6 in Embodiment 2;

Fig. 8 is the sectional view of C-C section among Fig. 7;

FIG. 9 is a schematic cross-sectional view of the fluidic optical waveguide 6 in Embodiment 3;

In the figure: 1-substrate I, 2-structural layer, 3-substrate II, 4-metal electrode, 5-input port, 6-fluidic optical waveguide, 7-output port, 8-polymer film, 9-fluid, 10 - light beam, 11 - fluid covering layer, 12 - fluid guiding layer.

Detailed ways

Example 1:

Referring to accompanying drawings 1 and 2, the fluidic optical waveguide structure proposed by the present invention includes substrate I1, structural layer 2 and substrate II3 in sequence, the materials of substrate I1 and substrate II3 are both PI, and the material of structural layer 2 is PDMS; structural layer There are micro-channels parallel to the substrate I1 and the substrate II3 on the 2. The micro-channels are filled with deionized water, and the two ends of the micro-channels are respectively connected with the input port 5 and the output port 7. A pair of nickel metal electrodes 4 are respectively located on the substrate I1 and the substrate II3. on the corresponding position to directly heat the fluid in the microchannel.

In this embodiment, the method of heating electrodes is used to form the fluidic optical waveguide. Applying a constant current to the nickel metal electrode 4 causes the temperature of the nickel metal electrode 4 to rise. Due to heat transfer, the temperature of the deionized water area in contact with the nickel metal electrode 4 in the micropipe increases, so that the refractive index of the deionized water in this area decreases. , the deionized water in the micropipe forms regions with different refractive indices. Referring to accompanying drawing 4, the region in contact with the nickel metal electrode 4 constitutes the fluid covering layer 11, and the deionized water region sandwiched between the fluid covering layers 11 constitutes Fluid waveguide layer 12, refer to accompanying drawing 5. Since there is a refractive index gradient between the fluid waveguide layer 12 and the fluid cover layer 11 , the light beam 10 propagates in the fluid waveguide layer 12 in the manner shown in FIG. 6 .

Referring to accompanying drawing 4 and accompanying drawing 5, when applying identical constant current to the nickel metal electrode 4 on the substrate I1 and the substrate II3, the temperature of the nickel metal electrode 4 on the substrate I1 and the substrate II3 increases synchronously, and the transfer rate of heat is the same , therefore form the same fluid cover layer 11 with the same height h, and the fluid waveguide layer 12 is in the middle of the micropipe; if the constant current applied to the nickel metal electrode 4 on the substrate I1 and the substrate II3 is not the same, the temperature of the two nickel metal electrodes 4 will be caused The different rising rates lead to different heat transfer rates, thus forming fluid covering layers 11 with different height h, and the fluid waveguide layer 12 deviates from the middle position of the micropipe. When the constant current applied to the nickel metal electrode 4 on the substrate I1 is greater than the constant current applied to the nickel metal electrode 4 on the substrate II3, the fluid waveguide layer 12 deviates downward, as shown in Figure 5B; when applied to the substrate When the constant current of the nickel metal electrode 4 on I1 is smaller than the constant current of the nickel metal electrode 4 applied on the substrate II3, the fluid waveguide layer 12 deviates upward, as shown in FIG. 5C . Therefore, by controlling the magnitude of the constant current applied to the nickel metal electrodes 4 on the substrates I1 and II3, the relative positional relationship between the fluid waveguide layer 12 and the fluid covering layer 11 is changed to achieve spatial modulation of the beam.

Since a pair of nickel metal electrodes 4 are respectively located at the corresponding positions on the substrate I1 and the substrate II3, when a constant current is applied to the nickel metal electrodes 4, the refractive index of the deionized water in contact with the micropipelines changes, only at In the direction perpendicular to the substrate I1 and the substrate II3, the refractive index of the fluid waveguide layer 12 is greater than the refractive index of the fluid covering layer 11, thus forming a planar waveguide.

Example 2:

Referring to accompanying drawing 7 and accompanying drawing 8, the fluid optical waveguide structure that the present invention proposes comprises substrate I1, structural layer 2 and substrate II3 successively, and described substrate I1 and substrate II3 material are all PMMA, and structural layer 2 material is PDMS; There are micro-pipes parallel to the base I1 and base II3 on the 2, the micro-pipes are filled with ethanol, and the two ends of the micro-pipes are respectively connected with the input port 5 and the output port 7, and a pair of copper metal electrodes 4 are respectively located on the two inner walls of the structural layer 2 above to directly heat the fluid in the microchannel. In order to ensure the insulation between the metal electrode 4 and ethanol, the surface of the metal electrode 4 is covered with a polymer film 8 made of polyvinyl alcohol.

In this embodiment, the method of heating electrodes is used to form the fluidic optical waveguide. Applying a constant current to the copper metal electrode 4 causes the temperature of the copper metal electrode 4 to rise. Due to heat transfer, the temperature of the ethanol region in contact with the copper metal electrode 4 in the micropipe increases, so that the refractive index of the ethanol in this region decreases. The ethanol in the pipeline forms regions with different refractive indices, the region in contact with the copper metal electrode 4 constitutes the fluid covering layer 11 , and the ethanol region sandwiched between the fluid covering layers 11 constitutes the fluid waveguide layer 12 .

Since the copper metal electrodes 4 are located on the two inner walls of the structural layer 2, when a constant current is applied to the copper metal electrodes 4, the refractive index of the ethanol in contact with the copper metal electrodes in the micropipes changes, and only in the direction perpendicular to the inner walls can the fluid The waveguide layer 12 has a higher refractive index than the fluid cover layer 11, thus forming a planar waveguide.

Example 3:

Referring to accompanying drawing 9, the fluidic optical waveguide structure proposed by the present invention includes substrate I1, structural layer 2 and substrate II3 in sequence, the materials of substrate I1 and substrate II3 are both glass, and the material of structural layer 2 is SU-8; There are micro-channels parallel to the substrates I1 and II3. The micro-channels are filled with calcium chloride solution, and their two ends are respectively connected to the input port 5 and the output port 7. The nickel-aluminum alloy electrode 4 covers the entire micro-channel to directly heat the micro-channel. fluid in. In order to ensure the insulation between the nickel-aluminum alloy metal electrode 4 and the calcium chloride solution, the surface of the nickel-aluminum alloy metal electrode 4 is covered with a polymer film 8 made of PI. Due to the existence of manufacturing process errors, the nickel-aluminum alloy metal electrodes on the substrate I1 and the substrate II3 cannot be in good contact with the nickel-aluminum alloy metal electrodes on the inner wall of the structure layer 2. Therefore, the nickel-aluminum alloy metal electrodes on the substrate I1 and the substrate II3 are fabricated When using an alloy metal electrode, the width of the nickel-aluminum alloy metal electrode is greater than the width of the micropipe.

In this embodiment, the method of heating electrodes is used to form the fluidic optical waveguide. Applying a constant current to the nickel-aluminum metal electrode 4 causes the temperature of the nickel-aluminum metal electrode 4 to rise. Due to heat transfer, the temperature of the calcium chloride solution area in contact with the nickel-aluminum metal electrode 4 in the micropipe increases, so that the calcium chloride in this area The refractive index of solution reduces, and the calcium chloride solution in micropipe forms the zone with different refractive index, and the zone that contacts with nickel-aluminum metal electrode 4 constitutes fluid covering layer 11, and the calcium chloride that is sandwiched between fluid covering layer 11 The solution region constitutes the fluidic waveguiding layer 12 .

Since the nickel-aluminum-aluminum metal electrode 4 covers the entire micropipe, when a constant current is applied to the nickel-aluminum-aluminum metal electrode 4, the refractive index of the calcium chloride solution in the micropipe in contact with it changes, and the flow rate of the fluid in any direction is satisfied. The refractive index of the wave guiding layer 12 is greater than that of the fluid covering layer 11 , and light beams can propagate in any direction in the fluid guiding layer 12 , thus forming a cylindrical waveguide.

Claims (4)

1. A fluid optical waveguide structure, comprising a substrate I (1), a structural layer (2) and a substrate II (3) in turn, the structural layer (2) has a substrate parallel to the substrate I (1) and the substrate II (3) The micro-pipe is filled with fluid, and the two ends of the micro-pipe are respectively connected with the input port (5) and the output port (7). A pair of metal electrodes (4) are located on the substrate I (1) and the substrate II (3) respectively. on the position to directly heat the fluid in the micropipe; on the substrate I (1) and the corresponding positions of the input port (5) and the output port (7) on the structural layer (2), holes are arranged for the input of the fluid and output. 2. A fluidic optical waveguide structure according to claim 1, characterized in that: the position of the metal electrode (4) is replaced by being located on the two inner walls of the structural layer (2). 3. A fluidic optical waveguide structure according to claim 1, characterized in that: the position of the metal electrode (4) is replaced by covering the entire micropipe. 4. A fluidic optical waveguide structure according to any one of claims 1-3, characterized in that the surface of the metal electrode is covered with a polymer film (8).

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