JP4041895B2 - Micro flow sensor - Google Patents

Description

  The present invention relates to a flowmeter that measures the flow velocity of various fluids, and more particularly to a micro flow velocity sensor that can accurately measure the flow velocity of a minute fluid flowing in a narrow fluid flow path.

  Conventionally, when measuring the flow rate of a fluid flowing in a pipe, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-130703, a tracer is supplied into the fluid and the flow velocity of the tracer moving between two points in the pipe is measured. To measure the flow rate.

  However, in this method, it is necessary to mix some kind of tracer in the fluid. For example, when measuring the flow rate of a chemical reaction fluid, or using a fluid for analyzing the composition and characteristics of the fluid, such as high performance fluid chromatography (HPLC). In the field where it is not preferable to mix other substances in the fluid when it is necessary to accurately supply the microfluid, such as a bioreactor for bioresearch, when it is used for a precise supply part, It is not appropriate to measure the flow rate using the tracer as described above.

  On the other hand, as shown in, for example, Japanese Translation of PCT International Publication No. 2-503597, a cylinder for generating eddy currents is arranged in a fluid pipeline, and the cylinder generated by the vortex generated in accordance with the flow velocity of the fluid, that is, the flow rate is used. Vibration is also measured by an optical measuring unit provided in the cylinder, thereby measuring the flow rate.

  However, in such a vortex flow meter, the vortex is not generated unless the fluid flowing in the tube has a flow velocity higher than a predetermined flow rate, and therefore, it is not suitable for measuring the minute flow rate of the fluid flowing through the micropipe.

  In addition, for example, as shown in Japanese Patent Publication No. 9-348573, a heater is provided on a part of the peripheral wall of the fluid pipe line, a thermal resistance is provided at a position away from the heater, and the temperature change of the fluid heated by the heater is changed. There is also a method for measuring the mass flow rate by detecting the thermal resistance.

However, even in the method using the above-described thermal resistance, the temperature of the fluid is increased by heating the fluid, which is often not suitable for measuring the flow rate of the chemical reaction fluid. As described above, various flow rate measuring methods have conventionally existed. However, none of the flow meters suitable for the flow rate measurement of the chemical reaction fluid as described above, the flow rate measurement in the HPLC, or the bioreactor yet exist. Moreover, in the various prior arts as described above, when the flow direction is reversed, it is not possible to cope with the same apparatus.
JP 2003-130703 A JP-T-2-503597 JP-A-11-160120

  The problem to be solved by the present invention is that there is no need to introduce impurities into the fluid or cause a temperature change, and the minute flow rate can be accurately measured by directly measuring the amount of the machine that operates by the fluid flow. It is possible to obtain a micro flow meter that can measure and easily cope with the case where the flow direction is reversed.

In order to solve the above problems, the micro flow rate sensor according to the present invention has an opening that communicates with the outside at the end face, and forms a fluid flow path that flows in a direction perpendicular to the fluid flowing through the opening and communicates with the flow path of the passive unit body. And a passive part body comprising a passive plate disposed in the fluid flow path and displaced by the fluid, the fluid flow path flowing in a direction perpendicular to the fluid flowing through the opening of the substrate and the flow path cover. And an end surface located on the opposite side of the end surface having the opening of the substrate, and an opening communicating with the outside, and a fluid flow path that flows in a direction perpendicular to the fluid flowing through the opening and communicates with the flow path of the passive unit body A transparent flow path cover that forms a flow path forming body that forms a series of flow paths by sequentially stacking the substrate, the passive portion main body, and the flow path cover. To measure the displacement of the passive plate That includes a laser interferometer, in which to detect the flow velocity of the fluid flow path in the measurement displacement of the driven plate by the laser interferometer.

  Further, in another micro flow rate sensor according to the present invention, the passive plate is disposed in an opening of a flow channel chamber formed in the passive portion main body, and is supported by a flexible passive plate support member extending from a peripheral edge of the opening. Is.

  In another micro flow rate sensor according to the present invention, the passive plate support member and the passive plate are integrally formed with the passive portion main body.

  Since the present invention is configured as described above, it is not necessary to mix a tracer or the like in the fluid, and a minute fluid flow rate can be accurately measured by simple means, and the flow direction is reversed. There is an advantage of having bidirectionality that can be easily handled even in cases.

  In order to accurately measure a minute fluid flow rate by a simple means without mixing a tracer or the like, the present invention irradiates a laser on a passive plate that is arranged in a fluid flow path and is displaced by the fluid. The displacement of the passive plate is measured by a meter.

Substrate 2 is provided with apertures 7 formed in the end surface 6 as shown in the perspective view of FIG. 2, is provided with a substrate flow grooves 8 communicating with the opening 7 on the upper surface side in the figure in the substrate 2. In addition, although this board | substrate 2 can be formed from a various raw material, glass can be used as an example.

  As shown in the perspective view of FIG. 2, the substrate 2 includes an opening 7 formed in the end surface 6, and a substrate flow path groove 8 leading to the opening 7 is provided on the upper surface side of the substrate 2 in the drawing. In addition, although this board | substrate 2 can be formed from a various raw material, glass can be used as an example.

  Similarly, the flow path cover 4 is provided with an opening 11 on an end surface 10 facing the end surface 6 opposite to the end surface 6 on which the opening 7 of the substrate 2 is formed. It is provided on the lower surface side in the figure. Since the flow path cover 4 needs to transmit light from a laser interferometer disposed above, the flow path cover 4 is preferably made of glass.

As shown in FIGS. 2 and 3, the passive part main body 3 includes a central flow path chamber 14 that opens at the lower end surface 13 in the figure, and the central flow path chamber 14 is disposed on the upper end face 15 side of the passive part main body 3. Bei Eteiru passive plate 16 having a thickness of t. The passive plate 16 is supported at the upper center portion of the central flow channel chamber 14 by four passive plate support members 18 extending from the four corners of the rectangular opening edge 17 at the upper end of the central flow channel chamber 14. The above-mentioned passive plate 16 is actually 150 μm square, and the thickness t is manufactured to about 1.75 μm. Such a structure can be easily formed by etching technology in the field of semiconductor manufacturing technology by using a silicon material as the passive portion main body 3.

  Four passage openings 20 are formed by the four passive plate support members 18, and as a result, as shown in FIG. 3A, the openings 7 of the substrate 2, the substrate passage grooves 8, and the center of the passive portion main body 3. A series of fluid flow paths including a flow path opening 20 between the flow path chamber 14 and the passive plate support member 18, a cover flow path groove 12 of the flow path cover 4, and an opening 11 of the flow path cover 4 are formed. In the example shown in FIG. 3, an example is shown in which fluid flows in this order, and FIG. 1 shows an example in which fluid flows in a flow path opposite to this.

  As shown in FIG. 1, the laser interferometer 5 allows laser light to pass through a transparent flow channel cover 4 made of glass, and covers the flow channel groove 12 of the flow channel cover 4 and the fluid flowing through the cover flow channel groove 12. Is arranged so that the reflected light can be received, and the light reception signal is output to the personal computer 6. Various laser interferometers can be used as the laser interferometer 5, but a laser Doppler interferometer is preferably used in order to detect the movement of the passive plate 16 at high speed. At present, such a laser interferometer having a small size of about 47 mm × 38 mm × 19 mm is available, and detects the movement of a minute movable plate in the minute channel as described above of about 500 μm square. It has become easy to do.

  When using the micro flow rate sensor according to the present invention having the above-described structure, in the example shown in FIG. Inflow and discharge from the opening 7 of the substrate 2 are performed. In such a fluid flow, the passive plate 16 is displaced downward in accordance with the fluid velocity. The displacement is detected by the laser interferometer 5, taken into a personal computer, processed by a signal, and the flow rate is detected. As the laser interferometer 5, various interferometers such as a Michelson interferometer that have been used in various fields can be used, and the laser beam used is also a single-frequency homodyne type or A heterodyne type interferometer using two frequencies can also be used.

  When the fluid flow direction is opposite to that of the above embodiment as shown in FIG. 3, the passive plate 16 is displaced upward by the fluid flow, and the displacement is detected by the laser interferometer 5 to measure the flow rate. It can be performed.

  FIG. 4 shows the result of actually producing a micro flow rate sensor according to the present invention and conducting a measurement experiment. The graph in the figure shows the displacement of the passive plate obtained by the optical interferometer when a peristaltic tube pump is used and the water is pulsed by driving at various rotational speeds. In the experiment of the graph, after starting the pump, the frequency of the pulse operation of the pump was increased in order, and then decreased in order. When the pump operating frequency is low, the flow rate is corresponding to that frequency. Slow and passive plate displacement is small. Also at this time, as shown in the graph, it can be seen that even the state where the fluid is changing due to the pressure change due to the pulse period of the pump can be clearly detected.

  Moreover, when the drive frequency of the pump is changed, the displacement changes accordingly. From this, the passive plate measured by the laser interferometer 5 is obtained by obtaining the displacement characteristic data of the passive plate in advance. From the displacement measurement result, the flow velocity of the fluid flowing through the flow path can be accurately measured, and the accurate flow rate can be measured.

  The micro flow rate sensor according to the present invention can accurately measure the flow rate of a fluid flowing through a minute flow path, so that chemical reaction and substance production using a phenomenon in a minute space with a diameter of several μm to several mm is possible. The present invention can be effectively used in the technical field of measuring a chemical reaction fluid, which is an integrated system of unit operations such as mixing, reaction, and separation, in the biotechnological field, and in other similar technical fields.

It is explanatory drawing which shows the whole outline | summary of this invention. It is a disassembled perspective view of the flow-path formation main body in this invention. (A) is sectional drawing of the flow path formation main body, (b) is the top view. It is a graph which shows the result of having manufactured the micro flow rate sensor by this invention, and having conducted experiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow path formation body 2 Board | substrate 3 Passive part main body 4 Flow path cover 5 Laser interferometer 6 Personal computer 7 Opening 8 Substrate flow path groove 10 End surface 11 Opening 12 Cover flow path groove 13 Lower end surface 14 Central flow path chamber 15 Upper end surface 16 Passive Plate 17 Opening edge 18 Passive plate support member 20 Flow path opening 21 Upper end surface

Claims (3)

An end surface having an opening that communicates with the outside, a substrate that forms a fluid flow path that flows in a direction perpendicular to the fluid flowing through the opening and communicates with the flow path of the passive unit body;
A passive section body including a fluid flow path that flows in a direction perpendicular to the fluid flowing through the opening of the substrate and the flow path cover, and a passive plate that is disposed in the fluid flow path and is displaced by the fluid;
An end face located opposite to the end face provided with the opening of the substrate is provided with an opening communicating with the outside, and a fluid flow path is formed which flows in a direction perpendicular to the fluid flowing through the opening and communicates with the flow path of the passive part body. With a transparent flow path cover ,
Laminating the substrate, the passive part main body and the flow path cover in order to form a flow path forming body that forms a series of flow paths,
A laser interferometer that measures the displacement of the passive plate of the passive unit body through the flow path cover,
A micro flow rate sensor that detects a flow rate of a fluid in a flow path by measuring displacement of a passive plate by the laser interferometer.   The said passive board is arrange | positioned in the opening of the flow-path chamber formed in the passive part main body, and is supported by the flexible passive board support member extended from the periphery of the said opening. Micro flow rate sensor. 3. The micro flow rate sensor according to claim 2, wherein the passive plate support member and the passive plate are integrally formed with the passive portion main body.

Images