JPH05248356A - Detection device for use in micropump - Google Patents

Abstract

PURPOSE:To provide a detection device for performing control of micro flow using a micropump. CONSTITUTION:A detection device 100 has an electric circuit switching mechanism formed by forming a conductivity-enhanced protrusion 53 on a partition wall 52 comprising an outlet valve 5 provided in a thin film plate 2, and joining the back electrode plate 300 of an opposite surface plate 3 to the protrusion 53. The behavior of the outlet valve 5 appears as the elastic deformation of the partition wall 52 and the conductivity-enhanced protrusion 53 makes contact with the back electrode plate 300 of the surface plate 3, so the behavior of the outlet valve 5 is detected indirectly through the detection of the vibrational waveform of the protrusion as an electric signal applied between the protrusion 53 and the back electrode plate 300 of the surface plate 3. Since in a micropump 10 the vibrational waveform of the outlet valve portion 5 is stably detected using the electric circuit switching mechanism, whether or not the action of the pump is normal can precisely be determined according to the vibrational waveform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micropump to which a micromachining technique is applied, and more particularly to a detection device for detecting the state of a valve portion in a 2-valve or 3-valve type micropump.

[0002]

2. Description of the Related Art Micro pumps to which Si micromachining technology is applied are described in, for example, Nikkei Electronics No. 480, pp. 135-139 (1989)
It was published on August 21, 2012. There are two types of micropumps, one with two valves (inlet / outlet valves) and the other with three valves (three in total including an inlet / outlet valve and an intermediate valve), each having advantages and disadvantages. The advantages and disadvantages of each are not mentioned here.

The two-valve structure will now be constructed as shown in FIG.

A Si thin film plate 201 is formed on a glass substrate 200.
The two valves 202 and 203 and the diaphragm 204 are formed between them and are joined together, and the glass plate 205 is further joined onto the Si thin film plate 201 to form the diaphragm 20.
4 is driven by the heating resistor 207 via the air layer 206. The glass substrate 200 has bulbs 202 and 203.
To the inlet port 208 and the outlet port 20 respectively leading to the
9 is provided, and when the diaphragm 204 swells due to the air expansion of the air layer 206, the inlet valve 202 is closed and the outlet valve 20 is closed due to the increase in the internal pressure of the pump chamber 210.
3 to open the pressure fluid in the pump chamber 210 to the outlet port 2
09, while the diaphragm 204 returns to its original position due to the contraction of the air layer 206, the valves 202 and 203 operate in the opposite directions, sucking fluid from the input port 208 and discharging to the outlet port 209 of the valve 203. It is designed to shut off when closed.

It is suggested that such a micropump can be applied to medical purposes (insulin medication of diabetic patients, etc.) and chemical analysis because it can control a minute amount of precise flow rate.

[0006]

It is possible to precisely control a minute flow rate with a micropump, especially by controlling the diaphragm portion and the valve portion. Therefore, it is important to detect the operating state of such a portion with high accuracy. For example, considering the use for insulin medication, the back pressure at the output port requires a required head pressure (for example, 40
It is necessary to always discharge a constant flow rate below 0 mmH2O), but such flow rate control becomes possible only by highly precise control of the diaphragm section and the outlet valve section.

It is an object of the present invention to provide a valve detection device which is indispensable for controlling a minute flow rate by a micropump.

[0008]

In order to achieve the above object, a detection device in a micropump according to the present invention is a two-valve or three-valve micropump, in which an outlet valve is provided as a detection means of a valve portion. A means for detecting the partition wall is provided. The detecting means is the electric circuit opening / closing mechanism formed by a projection on the partition wall and an electrode plate joined to the back surface of a front plate facing the projection.
The electric circuit opening / closing mechanism is formed by an electrode plate reaching a protrusion on the partition wall and an electrode plate joined to a back surface of a front plate facing the protrusion.

Next, as a detecting means, a space between the contacts in the electric circuit opening / closing mechanism is provided by etching the back surface of the face plate or the projection on the partition wall.

Next, as a detecting means, a contact material for high voltage and high current having a high melting point and a high hardness is provided on at least one electrode of the electric circuit opening / closing mechanism.

Next, as the detecting means, a voltage dividing circuit is provided in which the voltage applied to the electric circuit opening / closing mechanism is a low DC voltage.

The above is the detection means by the electric circuit opening / closing mechanism.

Further, the detecting means for the valve portion, the time width from the rising to the falling of the waveform, and the R
A detection circuit is provided to determine whether the time is normal by comparing with the time width table set in OM.

[0014]

In the micropump according to the present invention, the piezoelectric element for driving the diaphragm periodically vibrates the diaphragm to discharge a constant minute flow rate. Therefore, it is possible to accurately determine whether or not the operation is normal by detecting the vibration waveform of the output valve. As the detection device, it is preferable to use an electric circuit opening / closing mechanism (switch) which is stable in detection operation and inexpensive.

Further, the method of judging the detection result is such that the time width from the rising edge to the falling edge of the waveform and R
The time width table set in OM is compared to determine whether it is normal. For example, if it is 10 ms to 40 ms, it is determined to be normal, and otherwise, it is determined that some trouble has occurred.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of a micropump according to the present invention, showing a case of two valves. Figure 2
3 and 4 are cross-sectional views taken along the lines AA and BB of FIG. 1, respectively.

First, the structure of the micropump will be described.

The micropump indicated by reference numeral 10 has a sandwich structure of a substrate 1, a thin film plate 2 and a surface plate 3. The substrate 1 is made of, for example, a glass substrate having a thickness of about 1 mm, and is provided with an input port 11 and an output port 12. Tube 1 for each of these ports
A bonding test was performed with an adhesive 15 so that liquids 3 and 14 would not leak, and the proximal end of the tube 13 was, for example, a chemical liquid tank (not shown).
The tip of the tube 14 is connected to, for example, an injection needle (not shown).

The thin film plate 2 is made of, for example, a Si substrate having a thickness of about 0.3 mm, and the inlet valve 4,
An outlet valve 5 and a diaphragm 6 are formed between both valves, and a necessary flow path (see FIGS. 2 and 3) is provided, and the substrate 1 is joined by an anodic bonding method. Symbol 1 for the joint
It is a part shown by 6a and 16c.

As shown in FIGS. 2 and 3, an input flow passage 111 is provided so as to be connected to the inlet port 11, and the input flow passage 11 is provided.
1 communicates with a chamber 113 provided above the outlet valve 5 through a through hole 112, and further communicates with a chamber 116 of the input valve 4 through a through hole 114 and a communication passage 115. The input valve 4 is composed of a square valve body 41, a through hole 117 is provided at the center thereof, and communicates with an upper chamber 118. Further, the chamber 118 communicates with the pump chamber 121 below the diaphragm 6 through the through hole 119 and the communication flow passage 120, and the pressure fluid flows through the output flow passage 122 into the chamber 123 of the outlet valve 5. The outlet valve 5 is connected to the inlet 12 of the output port 12.
It is formed of a cap-shaped square valve body 51 that covers a. As a driving means of the diaphragm 6, a piezoelectric element 7 of a piezo disk is adhered on the diaphragm 6 via an electrode plate 71 of a thin film plate.

In the figure, 72 and 73 are lead wires for applying a voltage to the piezoelectric element 7.

A surface plate 3 made of a glass substrate similar to the substrate 1 is provided on the thin film plate 2 by an anodic bonding method by providing an insertion port 31 for the piezoelectric element 7 to establish the pump flow path system. There is. The thickness of the face plate 3 is about 1 mm.

Next, the structure of the detection chamber 100 will be described. The detection chamber 100 is formed integrally with the micropump so as to detect the behavior of the partition wall 52 provided with the outlet valve portion of the micropump 10.

As shown in FIG. 1, the detection device 100 has a projection 53 on a partition plate 52 in which an outlet valve 5 is provided on a thin film plate 2.
And the back electrode plate 3 of the front plate 3 facing the protrusion 53.
It has an electric circuit opening / closing mechanism 101 formed by 00. The behavior of the outlet valve 5 appears as an elastic displacement of the partition wall 52, and the protrusion 53 contacts the back electrode plate 300 of the front plate 3. Therefore, the vibration waveform thereof is applied between the protrusion 53 and the back electrode plate 300 of the front plate 3. The behavior of the outlet valve 5 can be indirectly detected by detecting the change in the signal amplitude. The contact portion of the protrusion 53 in the electric circuit opening / closing mechanism 101 is a high conductor 102 whose electric resistance is lowered by diffusion of impurities such as B and P.

Next, FIG. 4 shows an embodiment of the detection device 100 for the valve portion, particularly the outlet valve 5. As shown in FIG. 4, the protrusion 53 is formed on the partition plate 52, and the protrusion 53
This is the case where the electrode plate 54 reaching the above is provided.

In FIG. 5, in order to obtain a space between the contacts provided in the electric circuit opening / closing mechanism 101, the back surface of the surface plate 3 facing the projection 53 is etched to bond the electrode plate 300 to the projection 53.
This is a case where the electrode plate 54 is provided only on the upper part of.

Similarly, FIG. 6 shows the case where the electrode plate 54 is provided by etching the upper portion of the projection 53 on the partition plate 52 provided with the outlet valve 5 on the thin film plate 2.

FIG. 7 shows the case where a high melting point and high hardness contact material 400 for high voltage and high current is provided on at least one electrode of the electric circuit opening / closing mechanism 101. Electric circuit opening / closing mechanism 101
Examples of the contact material used for Pt-Ir, W, T
a, Ni, Pt, Pd, Mo, Ti, polySi,
WSi2, MoSi2, CP1 and CP3 are used.

In the case of Pt-Ir, Ta or C is used as the base.
The adhesion of Pt-Ir (48:52) of about 2000 angstrom is secured by setting r to about 500 angstrom.

FIG. 8 shows a driving circuit of the driving piezoelectric element 7 and a circuit configuration in which a detection circuit of the outlet valve detecting device 100 (electric circuit opening / closing mechanism) is added to this circuit, and FIG. 12 shows the operation of the embodiment of FIG. Indicates the state.

In FIG. 8, 701 is a power source such as a lithium battery, 702 is a booster circuit, 703 is a CPU, 704 is a level shifter for converting a low voltage signal into a high voltage signal, 70
Reference numeral 5 is a driver for driving the piezoelectric element 7, 706 is a display device for displaying the flow rate of the pump, 707 is a flow rate selection switch, and 708 is a detection circuit. First, the flow rate is selected by the switch 707, and the pump drive signal is output from the CPU 703. The signal of the CPU 703 generally operates at a voltage of 3 to 5V, and the piezoelectric element 7 is operated to output a high voltage such as 100V. Then, the voltage of 3V is set to 1 by the booster circuit 702.
The voltage is boosted to 00V and the CPU 7 is operated by the level shifter 704.
The signal from 03 is converted into a signal of 100V.

As described above, the voltage of 100 V is periodically applied to the piezoelectric element 7 to give vibration of 0.5 Hz to several tens Hz. When the diaphragm 6 bends downward as shown in FIG. 9A due to the piezo effect, the pressure in the pump chamber 121 rises,
This pressure is applied to the chamber 11 through the flow paths 120 and 122, respectively.
8 and 123 are simultaneously transmitted to increase the internal pressure. Partition wall 4 provided with inlet valve 4 due to increase in internal pressure of chamber 118
2 is pushed downward and the valve body 41 of the inlet valve 4 is pressed against the substrate 1, so that the inlet valve 4 is closed. At the same time, since the partition wall 52 is pushed up by the increase in the internal pressure of the chamber 123, the valve body 51 of the outlet valve 5 separates from the substrate 1, the outlet valve 5 opens, and a fixed amount of fluid is discharged to the outlet port 12.

When the applied voltage becomes 0 V, the diaphragm 6
Returns to the initial state as shown in FIG. 9B, and the pump chamber 121
As a result, the partition wall 52 of the chamber 123 is deflected downward, the output valve 5 is closed, and at the same time, the partition wall 42 of the chamber 118 is deflected upward and the inlet valve 4 is opened.
A fixed amount of liquid is sucked from the chamber 116 communicating with the inlet port 11 through 17.

By vibrating the diaphragm 6 by the piezoelectric element 7, the above-mentioned suction and discharge are continuously performed, and if the frequency is increased, a pump with less pulsating flow can be obtained. In this case, since the output valve 5 is formed by the valve element 51 on the cap that covers the input 12a of the output port 12, the lifting force of the partition wall 52 (the opening force of the outlet valve 5) due to the back pressure of the output port 12 is increased. The acting direction is the same as the pushing direction of the pressure of the pump chamber 121 against the partition wall 52, and the back pressure always acts on the outlet valve 5 in the opening direction. Therefore, until the back pressure overcomes the pressing force based on the elastic force of the outlet valve 5 and the external force exerted on the partition wall 52, that is, a substantially constant flow rate is discharged in the required pump usage range.

The flow rate performance of this micropump is shown in FIG. 10, and the pressure difference P is about 400 mmH2O.
Up to a constant flow rate Q is discharged.

Further, the detection device 100 and the detection circuit 708.
The operation of is as follows.

When a drive voltage is applied to the piezoelectric element 7, the CPU 703 reads the state of the electric circuit opening / closing mechanism 101 for detection and the detection circuit 708 at a predetermined timing in synchronization with the applied voltage. When a defect is detected, the CPU 703 outputs a drive stop signal or causes the display device 706 to display the defect. The detection circuit 708 amplifies or rectifies the signal from the electric circuit opening / closing mechanism 101 and measures the time width from rising to falling to make a comparison (a function of a counter in the circuit), and the CPU 703 outputs the signal. It works to send signals.

FIG. 11 is a waveform diagram showing an example of the output waveform of the detection electric circuit opening / closing mechanism 101. As shown in FIG. 12A, a voltage pulse of 100 V, 1 Hz is applied to the driving piezoelectric element 7. 12 is an amplified output of the detection electric circuit opening / closing mechanism 101 on the outlet valve (see FIG. 12B).

In FIG. 11, P is a waveform when the pump is normal, Q is a waveform when air is contained in the pump, and R is a waveform when the pump or injection needle is clogged. The minimum time width Tmin and the maximum time width Tmax are reference voltages set in advance for the detection circuit 708 to determine a failure occurrence state, and the detection electric circuit switching mechanism 10 is provided.
It is preset in the ROM for comparison with the time width TW from the rising edge to the falling edge of the output pulse of 1. Further, the average time width TAVE in the driving period is calculated and stored in the RAM for a certain period after the start of driving, and the fluctuation rate E of the current time width Tw is detected by the detection circuit 708.
And the maximum fluctuation rate Emax calculated by the CPU 703 and set in the ROM in advance, and the defect occurrence state is determined. For example, Tmin = 10 ms, Tmax = 40 ms, E
max = 60% (how to take Tmin, Tmax, Emax can be changed by the index of the table) (Tmin, Tmax, Emax) = (10, 40, 60) E = (Tw-Tave) / Tave * 100 [ %] Tave = 25ms P (normal); TW = 30ms Tmin <Tw <Tmax, E = 2% <Emax Q (when air is in); Tw = 5ms Tmin> Tw <Tmax, E = 80% > Emax R (in the case of clogging); TW = 45 ms Tmin <Tw> Tmax, E = 80%> Emax, so the state at the time of occurrence of a defect can be detected.

FIG. 13 schematically shows the relationship between the fault state and the output waveform of the detection electric circuit opening / closing mechanism.

(A) When air is contained in the pump Since the pressure is used only for compressing the air, the detection waveform of the outlet valve portion remains low or the high time width becomes short.

(B) When the pump tube or needle tip is clogged: The outlet valve moves up and down in a reverse phase with a sharp rise in response to the vibration of the diaphragm, so the detected waveform of the outlet valve remains high, or High duration becomes longer.

(C) When there is a leak in the pump or when the inlet valve is clogged with dust and remains open The same as above (a).

(D) When a strong force is applied to the tank At the moment when the pressure P is applied, the pressure becomes the same as in (b) and continues until the pressure is released. (E) In the case of cracking of the driving piezoelectric element / diaphragm and disconnection of the lead wire, the same as above (a).

(F) When the outlet valve remains open due to back pressure, or dust is stuck in the outlet and remains open. Same as (b) above.

When a defect occurs as described above, a difference from the normal state appears in the waveform. Further, when the inside of the pump is switched from the compressible air to the incompressible liquid and the switching timing of the opposite state can be detected from the detected waveform.

Although the two-valve micropump has been described in the above embodiments, a three-valve micropump can be similarly applied.

[0048]

As described above, according to the present invention, the following effects can be obtained.

(1) In the two-valve or three-valve micropump, the vibration waveform of the outlet valve portion is detected, so that it is possible to accurately judge whether or not the operation of the pump is normal from the vibration waveform. ..

(2) By using an electric circuit opening / closing mechanism (switch) for the detection device, a more stable and inexpensive structure can be obtained.

(3) A space between contacts provided in the detection electric circuit opening / closing mechanism can be made stable and inexpensive by etching the back surface of the front plate.

(4) More stable operation can be obtained by using a high-voltage, high-current contact material having a high melting point and a high hardness for at least one electrode of the detection electric circuit opening / closing mechanism.

(5) The detection circuit compares the time width from the rising edge to the falling edge of the waveform with the time width table set in ROM in advance, and compares the average time width in the driving period with the current time width. Since it is configured to determine whether it is normal or not based on the variation rate, highly accurate detection can be performed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a micropump provided with a detection device for an outlet valve according to the present invention.

FIG. 2 is a horizontal plan view taken along the line AA of FIG.

FIG. 3 is a horizontal plan view taken along the line BB of FIG.

FIG. 4 is a cross-sectional view showing a configuration example of an outlet valve detection device.

FIG. 5 is a cross-sectional view showing a configuration example of an outlet valve detection device.

FIG. 6 is a cross-sectional view showing a configuration example of an outlet valve detection device.

FIG. 7 is a cross-sectional view showing a configuration example of a detection device for an outlet valve section.

FIG. 8 is a block diagram showing a circuit configuration example of the embodiment of FIG.

9 (a) and 9 (b) are operation diagrams of the embodiment of FIG.

FIG. 10 is a characteristic diagram showing pump performance of the embodiment of FIG.

FIG. 11 is an explanatory diagram showing a method of determining a detected output waveform.

FIG. 12A is a voltage pulse waveform to be applied to the diaphragm driving element. (B) is an output waveform diagram of an electric circuit opening / closing mechanism for detecting a valve portion.

FIG. 13 is an explanatory diagram showing a relationship between a defect state and an output waveform at a detection location.

FIG. 14 is a sectional view of a conventional 2-valve type micropump.

[Explanation of symbols]

 1 ... Substrate 2 ... Thin film plate 3 ... Surface plate 4 ... Inlet valve 5 ... Outlet valve 6 ... Diaphragm 7 ... Piezoelectric element 10 ... Micro pump 11 ... Inlet port 12 ... Outlet port 52 ... Partition wall 53 ... Protrusion 54 ... Electrode plate 100 ... Valve detection device 101 ... Electric circuit opening / closing mechanism 102 ... High current contact material

Claims (5)

[Claims] 1. A substrate, a thin substrate bonded on the substrate, a diaphragm portion and at least two valve portions formed on the thin substrate, and a driving means for the diaphragm portion. In a micropump that controls a small amount of flow so that a fluid is sucked in from an inlet port and discharged to an outlet port of the substrate, the behavior of a partition wall provided with an outlet valve in the valve section is enhanced by conductivity diffusion to improve conductivity. A detection device in a micropump, comprising an electric circuit opening / closing mechanism formed by a projection on the partition wall and an electrode plate joined to a back surface of a surface plate facing the projection. 2. The electric circuit opening / closing mechanism, wherein the detecting means of the outlet valve portion is formed by an electrode plate reaching a protrusion on the partition wall and an electrode plate bonded to a back surface of the front face plate facing the protrusion. The detection device in the micropump according to claim 1, wherein the detection device is a micropump. 3. The detecting means according to claim 1 or 2, wherein a gap between contacts provided in the electric circuit opening / closing mechanism is provided by etching the back surface of the front plate or the projection. The detection device in the micropump according to claim 1. 4. The micro device according to claim 1 or 2, wherein a contact material for high voltage and high current having a high melting point and a high hardness is provided on at least one electrode of the electric circuit opening / closing mechanism. Detectors in pumps. 5. The detection means according to claim 1 and claim 2 compares the time width from the rising edge to the falling edge of the waveform with a time width table preset in ROM, and calculates the time width in the driving period. A detection device in a micropump, which has a detection circuit for determining whether or not it is normal based on a variation rate between an average and a current time width.