KR20050010246A - Microinjectors and Droplet Volume Adjustment Method using Microinjectors - Google Patents

Abstract

PURPOSE: A micro-injector and a method for adjusting a droplet volume using the same are provided to inject fluid to an exterior using the pressure of the fluid generated when energy is supplied. CONSTITUTION: A micro-injector injects fluid to an exterior using the pressure of a droplet generated when fluid supplied into a fluid passage through a fluid injecting hole is evaporated. A micro heating part(120) has a plurality of micro heating structures(121) in a matrix shape in a predetermined interval of the fluid passage. The micro heating part(120) is connected to an energy delivering part. The energy delivering part applies an external input signal to each micro heating structure and individually drives the micro heating structure. The micro heating part(120) has 1xN micro heating structures(121). The fluid injecting hole(112) is formed in a direction vertical to a growth direction of the droplet created by the micro heating part.

Description

Microfluidic Injector and Spray Droplet Size Control Method Using the Injector {Microinjectors and Droplet Volume Adjustment Method using Microinjectors}

The present invention relates to a microfluidic injector, and more particularly, to a microfluidic injector for injecting a fluid from the microfluid to the outside by using a pressure of bubbles generated when the fluid supplied into the microfluid is vaporized by receiving energy from the energy heating unit, and It relates to a method for adjusting the size of the spray droplet using the same.

In the printer market, inkjet printers have advantages such as relatively low price, low operating noise, and various color expressiveness. Recently, the inkjet printer has been in the spotlight due to the increase in color prints with the use of the Internet and digital cameras. In addition, as interest in the bioindustry increases, studies on microbiological sample injectors and micro drug injectors are being conducted. This application requires a technology capable of precisely dispensing the desired amount of a small amount of fluid, such as a trillion 1L at a desired time. To meet this requirement, a microfluidic injector capable of controlling the size of the ejected droplets is required.

The conventional microfluidic injector is configured to spray a spray droplet having a predetermined size by installing a single micro heating element having a rectangular or line shape in the microchannel. In addition, the conventional microfluidic injector is intended to adjust the application time of the voltage applied to the micro heater (energy heating unit) or to control the size of the droplets are sprayed using a heater having a different size. That is, the method of adjusting the voltage application time is to change the size of the bubbles generated by changing the size of the bubbles generated by changing the time of application of the input voltage, and the size of the bubbles is small and the analog method Due to the adjustment, it was difficult to control the exact droplet size. In addition, the method using a heater having a different size is to adjust the size of the droplets injected through the bubbles of different sizes generated for each heater. Since a single fluid injector requires a plurality of fluid ejection outlets, it takes up a lot of space and has various sizes. There was a difficulty in obtaining droplets with.

Looking at the prior art related to such a microfluidic injector is as follows.

U.S. Patent No. 6,137,502 (Dual droplet size printhead) is provided with different fluid jet streams including different micro heating parts in inkjet printheads for controlling the size of the jetting droplets, It is known to the art that the spray droplets are configured to spray at different fluid jets. However, this patent technique requires a different fluid jet as much as the size of the droplet to be obtained, and thus has a problem that the thermal density of the fluid jet is significantly lowered. Therefore, this patent technology has a problem that there is a limit in the size of the injection droplet to be adjusted.

In addition, US Patent No. 6,142, 599 (Variable drop mass inkjet drop generator) has an inkjet printhead that can control the size of the injection droplet, the pulse of the input electrical signal applied to the micro heating unit installed in the fluid injection port Techniques are known for using an ink of different viscosities using a number of pulses. However, this patent technology has a problem in that the size of the spray droplets is fixed to one when only one type of ink is used. In addition, this patent technique proposes a method of adjusting the volume of the spray droplets according to the heater operating by using two heaters of different sizes, in which case the size of the spray droplets is sprayed into three types (the droplet of the small heater). , Droplets of large heaters, droplets of small heaters + large heaters).

In addition, US Patent No. 6,276,782 (Assisted drop-on-demand inkjet printer) in the inkjet printhead (adjustable ink jet printhead) that can adjust the size of the injection droplet, the micro-heater is additionally installed at the end of the fluid injection port fluid It is known to utilize the viscosity change of the ink generated by additionally operating the micro heater as soon as the ink is ejected from the ejection port to change the temperature of the ejected ink according to its operating state. However, this patent technique is expected to take a long time to change the viscosity of the ink sufficiently because the heat generated from the additional micro-heater is located at the end of the ink injection port, and consequently has a problem of reducing the injection frequency. have.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, the number of the micro heating elements to operate by arranging a plurality of micro heating elements in the form of a matrix and each micro heating element can operate individually. And it is an object of the present invention to provide a microfluidic injector for adjusting the size of the spray droplets according to the combination and a method for controlling the size of the spray droplets using the same.

1 is a partially cutaway perspective view showing a configuration of a side fluid spray microfluidic injector according to an embodiment of the present invention;

FIG. 2 is a schematic view showing an arrangement of micro heating elements constituting the microfluidic injector of the side injection method shown in FIG. 1, wherein (a) illustrates a state in which micro heating elements are arranged in a matrix of 1 × N type. , (b) shows a state in which the micro heating elements are arranged in a matrix of N x N form, (c) shows a state in which the micro heating elements are arranged in a concentric circle matrix,

FIG. 3 is a schematic view illustrating a method of controlling spray droplets through the microfluidic injector illustrated in FIG. 1, wherein (a) illustrates a state in which a fluid is filled inside the microchannel before the micro heating element is operated. b) shows the state in which the minimum spray droplets are being sprayed by operating only one micro heating element, and (c) shows the state in which the larger spray droplets are being sprayed by operating several micro heating elements at once,

Figure 4 is a partially cutaway perspective view showing the configuration of the microfluidic injector of the top injection method according to another embodiment of the present invention,

FIG. 5 is a schematic view illustrating a method of controlling spray droplets through the microfluidic injector of the upper surface injection method shown in FIG. 4, wherein (a) illustrates a state in which the fluid is filled inside the microchannel before the micro heating element is operated. (B) shows a state in which the minimum injection liquid droplets are being sprayed by operating only one micro heating element, and (c) shows a state in which a larger spray droplet is being sprayed by operating several micro heating elements at the same time. One,

6 is a schematic diagram showing a manufacturing process of the microfluidic injector according to the present invention;

Figure 7 is a photograph showing the size of the microfluidic injector according to the present invention and the state bonded to the board for the test,

8 is a schematic diagram of a test apparatus for observing the growth and disappearance process of the micro-bubbles generated in the microfluidic injector according to the present invention,

9 is a photograph of each of the micro-bubbles generated in the microfluidic injector according to the present invention,

10 is a photograph of each of the injection droplets injected from the microfluidic injector according to the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

100: micro fluid injector 110: micro euro

111: inlet 112: injection hole

120: micro heating element 121: micro heating element

130: fluid 140, 160: bubble

150, 170: spray droplets

The present invention for achieving the above object, the micro-injecting the fluid to the outside through the injection port of the flow path using the pressure of the bubble generated when the fluid supplied into the flow path through the inlet is evaporated by the energy delivery unit A fluid injector, in which a plurality of micro heating elements are arranged in a matrix form in a predetermined section of the flow path, and the micro heating parts transmit the energy for driving each of the micro heating elements by individually applying the same external input signal. And an additional connection.

In addition, the present invention is the injection liquid in the microfluidic injector for injecting the fluid to the outside through the injection port of the flow path by using the pressure of the bubble generated when the fluid supplied into the flow path through the inlet is supplied with energy from the energy transfer unit vaporized As a method of controlling the size of the enemy, a minute heating unit in which a plurality of micro heating elements are arranged in a matrix form in a predetermined section of the flow path, and the micro heating units are individually driven by applying the same external input signal to each of the micro heating elements. The energy transfer unit is connected, characterized in that for controlling the size of the spray droplets in accordance with the number and combination of the micro heating element applied through the energy transfer unit.

In the following, with reference to the accompanying drawings, a preferred embodiment of the microfluidic injector and the method for controlling the size of the injection droplet using the same will be described in detail.

1 is a partially cutaway perspective view illustrating a configuration relationship of a side fluid injection microfluidic injector according to an exemplary embodiment of the present invention. As shown in FIG. 1, the microfluidic injector 100 of the present invention uses a pressure of bubbles generated when the fluid supplied into the microchannel is vaporized by receiving energy from an energy transfer unit, thereby moving the fluid from the microchannel to the outside. To spray. The microfluidic injector 100 of the present invention is arranged in a matrix form instead of a single micro heating element used in the conventional microfluidic injector, except that the microfluidic injector is configured to operate individually. Is configured in the same way as a conventional microfluidic injector.

That is, the microfluidic injector 100 of the present invention is configured to have a micro-channel 110 having an inlet 111 and an injection port 112 that are injected after the fluid is introduced into, and in a predetermined section of the micro-channel 110. The micro heating unit 120 in which the plurality of micro heating elements 121 are arranged in various matrix forms is provided. The micro heating unit 120 is connected to an energy transmission unit (not shown) for applying the same external input signal to each micro heating element 121 to individually drive the same. This energy transfer unit is configured to individually provide the same kind of signal to each micro heating element 121 in a conventional principle. Therefore, according to the present invention, droplets having various sizes may be sprayed according to the number and combination of the micro heating elements 121 to which the same type of signal applied through the energy transfer unit is applied.

The microfluidic injector 100 shown in FIG. 1 is a side injection method, and the injection hole 112 is formed in a direction perpendicular to the growth direction of bubbles generated in the microheater 120. That is, the microfluidic injector 100 of the side injection method of the present invention is configured such that the inlet 111 and the injector 112 through which the fluid is introduced and injected penetrate on the same line.

FIG. 2 is a schematic view showing an arrangement of micro heating elements constituting the microfluidic injector of the side injection method shown in FIG. 1, wherein (a) illustrates a state in which micro heating elements are arranged in a matrix of 1 × N type. , (b) shows a state in which the micro heating elements are arranged in an N x N matrix, and (c) shows a state in which the micro heating elements are arranged in a concentric matrix.

As shown in FIGS. 1 and 2, the microfluidic injector 100 of the present invention closely arranges a plurality of micro heating elements 121 formed in a quadrangular or annular shape, and arranges the micro heating elements 120 in a matrix form. As shown in FIG. 2A, the micro heating elements are arranged in a matrix of 1 × N form, or the micro heating elements are arranged in an N × N matrix as shown in FIG. As shown in (c), the micro heating elements are arranged in a concentric matrix.

The energy transmitting units are connected to the micro heating elements having a rectangular or annular shape arranged in this manner. Therefore, the spray droplets having various sizes may be sprayed according to the number and combination of the micro heating elements applied through the energy transfer unit. In addition, the present invention may be configured in a variety of forms, including a rectangular or annular form, but may be configured in any form as long as it can be arranged in a matrix form.

Figure 3 is a schematic diagram showing a method of controlling the spray droplets through the microfluidic injector shown in Figure 1, (a) shows a state in which the fluid is filled inside the micro-channel before the micro heating element is operated, (b) shows a state in which the minimum injection liquid droplets are being sprayed by operating only one micro heating element, and (c) shows a state in which a larger spray liquid is being sprayed by operating several micro heating elements at the same time.

As shown in Figure 1 and 3, in operating the microfluidic injector 100 of the present invention, the signal is not applied in the energy transfer unit, the fluid before the micro heating element 121 is operated as shown in (a) The 130 is filled inside the micro flow path 110. Then, when a signal is applied to only one micro heating element 121 in the energy transfer unit, only one micro heating element 121 applied as shown in (b) operates to generate a small bubble 140, and the pressure of the bubble 140 is increased. By the minimum injection droplet 150 is injected through the injection port 112. However, when a signal is applied to the plurality of micro heating elements 121 in the energy transfer unit, several micro heating elements 121 applied as shown in (c) operate at the same time to generate larger bubbles 160 and such bubbles 160. Due to the pressure of the larger injection droplet 170 is injected through the injection port 112.

Therefore, the present invention may spray droplets having various sizes depending on the number and combination of micro heating elements applied through the energy transfer unit.

Figure 4 is a partially cutaway perspective view showing the configuration of the microfluidic injector of the top injection method according to another embodiment of the present invention. As shown in FIG. 4, the microfluidic injector 200 of the present invention is a microfluidic injector 100 of the embodiment except that the injection hole 212 of the microchannel 210 through which the fluid is injected is formed on the upper surface. It is configured in the same way. That is, the injection hole 212 is formed in the upper portion of the micro heating unit 220 arranged in the micro flow path 210. The microfluidic injector 200 illustrated in FIG. 4 is an upper surface spraying method, and the injection holes 212 are formed in the same direction as the growth direction of bubbles generated by the microheater 220. That is, the microfluidic injector 200 of the upper surface injection method of the present invention is configured such that the inlet 211 and the inlet 212 through which the fluid is introduced and injected penetrate in a vertical line.

In addition, in the present invention, the injection port may be formed on the lower surface of the microchannel in which the microheater is arranged. That is, the present invention may be formed in the direction opposite to the growth direction of the bubbles generated in the micro heating unit.

FIG. 5 is a schematic view illustrating a method of controlling spray droplets through the microfluidic injector of the upper surface injection method shown in FIG. 4, wherein (a) shows a state in which a fluid is filled inside the microchannel before the micro heating element is operated. (B) shows the state in which the minimum injection liquid droplets are being injected by operating only one micro heating element, and (c) shows the state in which the larger injection liquid is being sprayed by operating several micro heating elements at once. It is shown.

4 and 5, the microfluidic injector 200 of the present invention operates in the same manner as described in the above embodiment. Therefore, the present invention may spray droplets having various sizes depending on the number and combination of micro heating elements applied through the energy transfer unit.

Experimental Example

Below will be described an example of the experiment to configure the microfluidic injector of the present invention configured as described above.

First, the microfluidic injector of the present invention was manufactured by the method shown in FIG. 6. In this case, a 1,000 μm thick TaAl thin film was used as a material of the micro heating element, and an aluminum thin film of 5,000 μm thick was used for electrical connection. In addition, the partition wall of the channel forming the micro-channel was made using a SU8 material having a thickness of 20㎛, and the production of the microfluidic injector of the present invention was completed by bonding Pyrex glass using an epoxy adhesive on top of the partition wall.

The total size of the microfluidic injector of the present invention manufactured as described above was 7,640 μm × 5,260 μm as shown in FIG. 7A, and the size of the micro heating element installed therein was 30 μm × 30 μm, and each micro The spacing between the heating elements was 5 μm, and the cross section of the injection hole was 20 μm × 20 μm. Thus, as illustrated in FIG. 7B, the substrate was bonded to an FPC board (Flexible Printed Circuit Board) for convenience of testing.

Then, as shown in Figure 8, using a test device designed to observe the growth and disappearance of the micro-bubble by time zone, the micro heating element of 10.0V, 1KHz, 1㎲ pulse-width digital electrical input signal of 40Ω After the application to, the growth and disappearance characteristics of the microbubbles were observed while increasing the number of micro heating elements. As shown in FIG. 9, the maximum size of the microbubbles was shown when 2 ms elapsed after the input signal was applied, but the time required for the microbubbles to disappear disappears as the number of the micro heating elements operating increased. From ㎲ to 8㎲ gradually increased. The reason is that while bubbles are growing, the initial bubbles from each micro heating element do not merge with each other and grow individually, so that the time taken to grow to the maximum when there is one bubble and several bubbles is the same, As the bubbles start to disappear, the grown bubbles are combined and the size varies depending on the number of bubbles, and the extinction time tends to increase with the number of micro heating elements. 9 (a) to 9 (d) show micro bubbles generated when one to four micro heating elements are operated.

10 is the number of micro heating elements sprayed from the microfluidic injector of the present invention to operate a photograph of micro droplets printed on paper [(a) is 1, (b) is 2, (c) is 3, ( d) is shown in [4], and the volume of the sprayed microdroplets was experimentally measured assuming the shape of the printed microdroplets as ellipsoidal hemispheres. That is, by measuring the length (2r _max , 2r _min ) of the long axis and short axis of the printed microdroplets, the volume (V _measure ) of the microdroplets was inferred using Equation 1 below.

Table 1 summarizes the lengths of the major and minor axes of the printed microdroplets measured experimentally, the volume of the microdroplets inferred therefrom, and their error bounds calculated from the 15 measurements. The margin of error of the major and minor axes measured from the printed microdroplets was ± 1 μm.

Working number of micro heating element One 2 3 4 Shortened average length of sprayed droplets [㎛] 7.4 12.0 13.1 16.5 Long axis average length of sprayed droplets [㎛] 12.5 13.9 16.6 21.5 Average volume of spray droplets [pℓ] 1.4 4.2 6.0 11.0 Volume of spray droplets [pℓ] 1.0 2.7 4.7 9.9 Volume of spray droplets [pℓ] 1.8 5.5 7.5 12.5 Average error of sprayed droplets [pℓ] 0.5 1.0 1.3 1.9

As shown in Table 1, it can be seen that the volume of the experimentally measured microdroplets is adjusted to 1.4 ± 0.5, 4.2 ± 1.0, 6.0 ± 1.3, 11.0 ± 1.9 p l depending on the number of micro heating elements that operate.

As can be seen from the above experimental example, the present invention can spray droplets having various sizes according to the number and combination of micro heating elements applied through the energy transfer unit.

As described in detail above, the microfluidic injector of the present invention arranges a plurality of micro heating elements in a matrix form and allows each micro heating element to operate individually, so that the size of the spray droplets depends on the number and combinations of the micro heating elements that operate. Since it can be adjusted, it is possible to eject droplets of various sizes accurately and quickly. Therefore, when the microfluidic injector of the present invention is applied to an inkjet printhead, high resolution and high speed injection can be simultaneously performed.

Moreover, this invention can be used for the apparatus which handles micro fluids, such as a micro biological sample injector and a micro drug injector.

Although the technical details of the microfluidic injector of the present invention and the method for controlling the size of the jetting droplet using the same have been described with the accompanying drawings, the exemplary embodiments of the present invention have been described by way of example and are not intended to limit the present invention.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations within the scope of the appended claims without departing from the scope of the technical idea of the present invention.

Claims (8)

A microfluidic injector for injecting a fluid to the outside through the injection port of the flow path by using the pressure of the bubble generated when the fluid supplied into the flow path through the inlet receives the energy from the energy transfer unit to evaporate, In a predetermined section of the flow path is a micro-heater is arranged in a plurality of micro-heater is arranged in a matrix form, the micro-heater is connected to the energy transfer unit for driving separately by applying the same external input signal to each micro-heater. Characterized in that the microfluidic injector. The microfluidic injector of claim 1, wherein the micro heating unit comprises the plurality of micro heating elements arranged in a matrix of a 1 × N form. The microfluidic injector of claim 1, wherein the micro heating unit comprises the plurality of micro heating elements arranged in an N × N matrix. The microfluidic injector of claim 1, wherein the micro heating unit comprises the plurality of micro heating elements arranged in a concentric matrix. The microfluidic injector according to any one of claims 1 to 4, wherein the injection hole is formed in a direction perpendicular to the growth direction of the bubbles generated in the micro heating unit. The microfluidic injector according to any one of claims 1 to 4, wherein the injection hole is formed in the same direction as the growth direction of the bubbles generated in the micro heating unit. The microfluidic injector according to any one of claims 1 to 4, wherein the injection hole is formed in a direction opposite to the growth direction of the bubbles generated in the micro heating unit. How to adjust the size of the spray droplets in the microfluidic injector that injects the fluid to the outside through the injection port of the flow path by using the pressure of the bubble generated when the fluid supplied into the flow path through the inlet receives the energy from the energy transfer unit to evaporate As The micro heating unit in which a plurality of micro heating elements are arranged in a matrix form is installed in a predetermined section of the flow path, and the energy transmitting unit for driving the micro heating elements individually by applying the same external input signal to each micro heating element is connected. And controlling the size of the spray droplets according to the number and combination of the micro heating elements applied through the energy transfer unit.