CN103439225A - Liquid dropping device used for measuring static contact angle - Google Patents

Abstract

The invention discloses a dripping device for measuring static contact angle, which comprises a needle, a piston rod, a rubber head, and a dripping syringe. The rubber head is installed at the lower end of the piston rod and is located in the dripping syringe, and The sealing contact of the drip syringe also includes a piston movement nut and a syringe movement nut. Both the piston rod and the outer wall of the drip syringe are threaded. The piston movement nut is installed on the piston rod, and the syringe movement nut is installed on the The middle and upper end of the drip syringe. The dripping device can accurately control the volume of the droplet within a certain range, and can ensure the complete shape of the natural formation of the droplet, avoiding the influence of the impact on the shape of the droplet when it falls.

Description

A Dropping Device for Measuring Static Contact Angle

technical field

The invention relates to the field of dripping, in particular to a dripping device for measuring static contact angles.

Background technique

According to authoritative scholars and related experimental results, the volume of the droplet affects the size of the static contact angle. If the droplet volume is too large, the static contact angle will decrease; if the droplet volume is too small, the static contact angle will increase. When the droplet volume is stable in a certain range, the static contact angle remains basically unchanged. According to the DL/T864-2004 international standard, the volume of water droplets used for static hydrophobic angle measurement should be 4-7 μL. In domestic and foreign experimental operations, the actual selection of volume standards varies. Some domestic researches choose larger than 5-6 μL, Braunschweig Technical University in Germany uses 30 μL, and surface and interface researchers generally use 2-5 μL.

In addition, if the falling speed of the droplet is too high, the impact force of the droplet will affect the balance of the surface force of the droplet, and the contour of the droplet will be deformed, and it will no longer be approximately spherical, thus affecting the measurement of the static hydrophobic angle. Therefore, it is of great significance to precisely control the droplet volume within a reasonable range and to control the droplet falling speed to accurately measure the static contact angle.

Among the existing dripping devices, the rubber dropper is a relatively common and practical instrument, but it cannot accurately control the droplet volume, so it cannot meet the requirements of measuring the static hydrophobic angle, and other simple instruments cannot simultaneously meet the droplet volume control , Droplet shape, drop speed requirements.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a dripping device for measuring static contact angle.

The present invention adopts following technical scheme:

A dripping device for measuring the static contact angle, comprising a needle, a piston rod, a rubber head, and a drip syringe, the rubber head is installed at the lower end of the piston rod, is located in the drip syringe, and is sealed with the drip syringe The contact also includes a piston movement nut and a syringe movement nut. The piston rod and the outer wall of the drip syringe are all threaded, and the piston movement nut is installed on the piston rod; the syringe movement nut is installed on the drip syringe. upper middle.

It also includes a bracket and a limit fixing screw, and the syringe movement nut is installed on the bracket through the limit fixing screw.

The drip syringe is also provided with a dial.

A door-shaped support is arranged above the dial, and the piston movement nut is arranged on the horizontal bar of the door-shaped support in the horizontal direction.

Marking lines are provided on the surface of the piston movement nut.

Beneficial effects of the present invention:

The dripping device can accurately control the volume of the droplet within a certain range, and can ensure the complete shape of the natural formation of the droplet, avoiding the impact of the drop when it falls on the shape of the droplet;

The device has the advantages of simple structure, easy manufacture, convenient maintenance, low cost, simple operation, and the use accuracy can meet the measurement requirements.

Description of drawings

Fig. 1 is a kind of structural representation of the dripping device that is used for measuring static contact angle of the present invention;

Fig. 2 is an enlarged view of part I in Fig. 1 .

The figure shows:

1-piston rod, 2-piston movement nut, 3-drip syringe, 4-syringe movement nut, 5-limit fixing screw, 6-bracket, 7-needle, 8-rubber head.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Figures 1 and 2, a dripping device for measuring the static contact angle includes a needle head 7, a piston rod 1, a rubber head 8, and a drip syringe 3, and the rubber head 8 is installed on the side of the piston rod 1 The lower end is located in the drip syringe 3, and also includes a piston movement nut 2 and a syringe movement nut 4. The outer walls of the piston rod 1 and the drip syringe 3 are threaded, and the piston movement nut 2 is installed on the piston rod 1. , the syringe movement nut 4 is installed on the middle and upper end of the drip syringe 3 .

The piston rod 1 is not in contact with the inner wall of the drip syringe 3, and the rubber head 8 is in sealing contact with the inner wall of the drip syringe 3, moves up and down in the drip syringe 3, and sucks in or squeezes out the liquid.

The top of the drip syringe 3 is provided with a dial, which is integrated with the drip syringe, and the two cannot move relative to each other. A door-shaped support is provided above the dial, and the door-shaped support includes two vertical bars and A cross bar, the piston movement nut 2 is arranged in the middle of the cross bar, the middle of the cross bar is hollow, the piston movement nut is fixed on a certain horizontal plane, so that the piston movement nut 2 can only rotate horizontally, and cannot move up and down.

The piston movement nut 2 is provided with a vertical marking line, which will rotate when rotating, and the dial will not move, and then read the volume of the pressed water droplet according to the scale of the lower dial corresponding to the marking line.

The piston rod 1 is threaded, and the piston movement nut 2 is installed on the piston rod 1 through the transmission thread. When a downward force is given to the piston rod 1, the piston movement nut is rotated at the same time, so that the piston movement 1 moves downward. The marking line on the 2 corresponds to the scale on the lower dial, and the rotating piston moves the nut 2 to precisely control the volume of the pressed droplet. For example, the scale of the dial is 0 μL to 20 μL, that is, every time the nut rotates one circle, 20 μL of liquid will be dripped out of the syringe.

The dripping syringe 3 is connected with the syringe moving nut 4 through the outer wall thread, and the syringe moving nut 4 is fixed on the bracket 6 by the limit fixing screw 5, and the dripping syringe can be moved up and down within a certain height range by rotating the dripping syringe. The syringe, dial, and door-shaped bracket are actually integrated, and the door-shaped bracket can be twisted by hand to rotate the drip syringe. After the needle point condenses into water droplets, rotate the needle cylinder to move the needle cylinder down slowly and at a uniform speed, and drop the water droplets onto the sample surface with the needle point.

The extreme position of the needle movement is limited by the dial of the drip syringe to avoid touching the sample to be tested, thereby damaging the device.

The limit fixing screw 5 ensures the positional relationship between the needle cylinder movement nut and the support 6, and prevents its relative movement.

The function of the bracket 6 is to fix the whole device, ensure the stability of the device during the measurement process, and fix the dripping area in the horizontal direction.

The entire set is made of plastic, lightweight and portable for easy fabrication.

The specific operation of using this device for dripping is as follows:

Aspirate the liquid to be measured:

Insert the needle into the container filled with liquid, adjust the piston movement nut, and drive the piston rod to move upward, so that the rubber head of the piston moves upward, and the liquid is sucked into the tube through the needle under the action of atmospheric pressure, and the liquid is replenished by observing the scale of the dial Volume until the required scale line is reached, and the operation of drawing and measuring liquid is completed.

Place the sample:

Place the device that has absorbed the measurement liquid above the surface of the object to be measured (note: the level of the surface to be measured was determined by a circular level before), fix the bracket, and rotate the drip syringe so that the needle drops to about 1cm from the surface of the object to be measured .

Control droplet volume:

Slowly rotate the piston movement nut to control the droplet volume according to the scale on the nut, and stop the rotation when the detection requirement is met. The rotation process will drive the piston rod to move downward, so that the rubber head will exert pressure on the liquid in the needle tube, so that the liquid will fall through the needle and become a droplet under the action of atmospheric pressure and surface tension; and hang at the end of the needle.

Drop operation:

In order to reduce the impact of the momentum on the droplet when the droplet falls to the surface of the object to be measured, the device uses a light touch method of the needle to drop the liquid. That is to say, after the previous step is completed, slowly rotate the needle cylinder so that the needle cylinder moves down as a whole, and the needle head continues to drop. During the downward movement, the intermittent downward movement method is adopted. During the downward process, the needle cylinder is rotated every 1/4 turn, that is, waiting After 5 seconds, wait for the liquid droplet on the needle to stabilize before continuing to rotate, so as to reduce the impact of vibration on the droplet caused by the downward movement of the support. Move down until the droplet contacts the surface of the object to be measured. At this time, under the action of surface tension, the droplet will form a hemispherical shape with the surface of the object to be measured. Stop rotating the needle cylinder, end the downward movement process, wait for about 5 seconds, and rotate the needle cylinder in the opposite direction after the vibration is eliminated, so that the needle moves upward slowly. The intermittent movement method is also adopted when moving, until the needle is completely separated from the droplet, and moves up to the upper part of the droplet, which is about 1 cm away from the highest point of the droplet, and the upward movement process ends.

After the droplet processing step is completed, the device can be removed, and the droplet can also be removed, and the experimental operation steps can be repeated to perform the operation again.

The droplet device can accurately control the volume of the droplet within the range of 0 μL to 20 μL, and can ensure the complete shape of the droplet’s natural formation, avoiding the impact on the shape of the droplet when it falls. The structure of the device is simple, easy to manufacture and maintain The utility model has the advantages of convenience, low cost, simple operation, and the use accuracy can meet the measurement requirements.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (5)

1. one kind for measuring the dropper of static contact angle, comprise syringe needle, piston rod, Rubber end, syringe drips, described Rubber end is arranged on the lower end of piston rod, and be positioned at the syringe that drips, and contact with the syringe sealing of dripping, it is characterized in that, also comprise piston movement nut, syringe movement nut, described piston rod and the syringe outer wall that drips all are threaded, and described piston movement nut is arranged on the piston rod; Described syringe movement nut is arranged on the middle upper end of the syringe that drips.

2. according to claim 1 a kind ofly it is characterized in that for measuring the dropper of static contact angle, also comprise support, spacing gib screw, described syringe movement nut is rack-mount by spacing gib screw.

3. according to claim 1 a kind ofly it is characterized in that for measuring the dropper of static contact angle, the described syringe that drips also is provided with index dial.

4. according to claim 3 a kind ofly it is characterized in that for measuring the dropper of static contact angle, described index dial top is provided with the door type support, and the piston movement nut is arranged on the cross bar of door type support in the horizontal direction.

5. according to claim 1 a kind ofly it is characterized in that for measuring the dropper of static contact angle, described piston movement nut surface is provided with markings.

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