A micro pipette with both air pressure and capacitance detection functions

Abstract

The application discloses a micro pipette with air pressure detection function and capacitance detection function, which comprises a metal shell, a plunger assembly, a push rod assembly, a driving assembly and a first control board. The plunger assembly comprises a connecting sleeve, a plunger and a metal sleeve. The metal sleeve comprises a cavity and a plug integrally connected to the bottom of the cavity. The cavity is sleeved on the outer periphery of the plunger. A PTFE film is arranged between the wall surface of the cavity and the outer periphery of the plunger. The first control board is provided with an air pressure detection assembly and a capacitance detection assembly. One end of an air pipe away from an air pressure detector is inserted into a first channel. One end of a wire away from a capacitance detector is fixed to the metal sleeve through a second channel. The metal sleeve comprises the cavity and the plug integrally connected to the bottom of the cavity, so that the pipette is miniaturized and has the air pressure detection function and the capacitance detection function. The PTFE film is used to reduce the gap between the cavity and the plunger and to reduce the dead volume of liquid suction and discharge.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pipettes, in particular to a micro pipette with both air pressure detection function and capacitance detection function. BACKGROUND

[0002] A pipette, also known as a pipette gun, is a measuring tool used to transfer a certain amount of liquid from a container to another container within a certain range, which is widely used in biological, chemical, medical and other fields.

[0003] In the prior art, referring to the pipette disclosed in Chinese patent CN216458938U, it includes an air pressure detection assembly, a capacitance detection assembly, and a plunger assembly. The plunger assembly includes a plunger cavity and a plug connected to the bottom of the plunger cavity. The plug is provided with a TIP head, and an O-ring is placed in the slot of the plug to rotate into the plunger cavity for sealing and splicing. However, this splicing form has the following shortcomings: 1. The dead volume of the plunger cavity is large (the space dead volume of the threaded screwing section is increased), which affects the precision of the pipette and the CV value of the suction and discharge of the liquid; 2. The threads at the connection are at risk of loosening after multiple insertions and extractions of the Tip head; 3. The O-ring seal also has an upper limit on the sealing life, which needs to be replaced in time to avoid affecting the precision; 4. The length of the threaded screwing section increases the overall length of the pipette; 5. In order to realize capacitance detection, a detection sheet with a length matching the plunger cavity is used to pass through the plunger cavity and electrically connect with the plug, which complicates the structure; 6. The plunger cavity and the plunger cannot be in direct contact, resulting in a large gap between them, i.e., a large dead volume for suction and discharge of liquid.

[0004] Therefore, it is necessary to design a new technical solution to solve the above problems. SUMMARY

[0005] In view of the above, the present application aims at the defects of the prior art, and the main purpose is to provide a micro pipette with air pressure detection function and capacitance detection function, which is sealed by the sealing ring, the first O-ring, the two second O-rings, and the two third O-rings, to seal the gaps between the plunger, the metal sleeve, the connecting sleeve, the connecting sleeve and the metal shell, and the metal sleeve and the connecting sleeve, respectively, so that the metal sleeve and the metal shell are not in contact, ensuring the accuracy of the capacitance detection function, and the metal sleeve includes a cavity and a plug integrally formed at the bottom of the cavity, so that the cavity and the plug do not need to be sealed and spliced, reducing the dead volume of the cavity, avoiding the risk of plug loosening after multiple Tip head insertions, improving the rigidity of the Tip head, making the pipette smaller and more flexible to use, and cooperating with the three-segment sealing to make the wire pass through the second channel and directly connect the metal shell, reducing the length and size of the capacitance detection assembly, making it easier to fix, and the middle part of the connecting sleeve is provided with a third channel communicating with the inside of the connecting sleeve and the first channel, so that the air pipe is inserted into the first channel at the end away from the air pressure detector, so that the pipette can have air pressure detection function and capacitance detection function, and the liquid level detection effect is better; and the PTFE film is arranged between the wall of the cavity and the outer periphery of the plunger to reduce the gap between the cavity and the plunger, reduce the dead volume of liquid suction and discharge, and improve the precision and CV value of liquid suction and discharge, and the self-lubricating performance of PTFE is excellent and has good biological compatibility.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A micro pipette with air pressure detection function and capacitance detection function, comprising:

[0008] A metal shell, the metal shell is provided with a containing groove, the bottom wall of the metal shell extends upwardly with an extension part, the bottom of the bottom wall of the metal shell is provided with a first installation groove and a second installation groove communicating with the containing groove and the outside of the metal shell, a first channel communicating with the first installation groove and the containing groove is arranged beside the extension part, an end cap is arranged on the bottom of the bottom wall of the metal shell, the end cap is provided with a first through hole and a second through hole corresponding to the first installation groove and the second installation groove, respectively, and the bottom wall of the metal shell and the end cap are provided with a second channel communicating with the containing groove and the first through hole;

[0009] A plunger assembly is arranged in the first mounting groove, and comprises a connecting sleeve, a plunger and a metal sleeve. The plunger is arranged in the first mounting groove, and the top end of the first mounting groove is provided with a first stop edge. The connecting sleeve is made of insulating material, and is arranged around the plunger. A sealing ring is arranged between the top of the connecting sleeve and the first stop edge. The bottom of the sealing ring extends into the connecting sleeve, and a first O-shaped ring is arranged between the inner wall of the connecting sleeve and the bottom of the sealing ring. A third channel is arranged in the middle of the connecting sleeve, and is in communication with the inside of the connecting sleeve and the first channel. Two second O-shaped rings are arranged between the outer periphery of the connecting sleeve and the first mounting groove, and are respectively arranged on the upper and lower sides of the third channel. A third mounting groove is arranged in the bottom of the connecting sleeve. The end cover is fixed to the first mounting groove through the metal sleeve. The top of the metal sleeve extends into the third mounting groove. Two third O-shaped rings are arranged between the outer periphery of the metal sleeve and the third mounting groove. The metal sleeve comprises a cavity and a plug which is integrally formed at the bottom of the cavity. The cavity is arranged around the plunger. A PTFE film is arranged between the wall of the cavity and the outer periphery of the plunger.

[0010] A push rod assembly is arranged in the second mounting groove, and comprises a push rod and a push sleeve which is connected to the push rod. The push rod is arranged in the second mounting groove. The push sleeve is arranged around the outer periphery of the metal sleeve.

[0011] A driving assembly is arranged in the accommodating groove, and is used for driving the push rod and the plunger to move up and down.

[0012] A first control board is arranged in the accommodating groove, and is arranged beside the first channel. The first control board is provided with an air pressure detection assembly and a capacitance detection assembly. The air pressure detection assembly comprises an air pressure detector and an air pipe which is connected to the air pressure detector. The end of the air pipe which is away from the air pressure detector is inserted into the first channel. The capacitance detection assembly comprises a wire which is connected to the first control board. The end of the wire which is away from the first control board is fixed to the metal sleeve through the second channel.

[0013] As a preferred solution, the driving assembly comprises a first motor, a first vertical screw rod and a first vertical sliding rail. The first vertical screw rod is connected to the first motor. The first vertical screw rod, the first vertical sliding rail and the first control board are arranged in the accommodating groove from left to right with a certain distance. The first vertical screw rod is provided with a first nut. The first vertical sliding rail is provided with a first sliding block. The first nut and the first sliding block are connected to a first linkage plate. The top of the plunger is connected to the first linkage plate. The top of the push rod can abut against the bottom of the first linkage plate.

[0014] As a preferred scheme, the accommodating groove is provided with a mounting position for mounting the first vertical slide rail, the mounting position is concavely provided with a clamping groove, the first vertical slide rail is fixed in the clamping groove, a plurality of mounting columns outside the clamping groove are arranged on the clamping groove, the first vertical slide rail is clamped in the clamping groove and fixed on the mounting columns, and the clamping groove and the mounting columns can greatly reduce the mounting height of the first vertical slide rail, thereby reducing the overall thickness of the pipette and making the pipette more compact.

[0015] As a preferred scheme, the metal shell comprises a first rear shell and a first front cover connected to the first rear shell, the accommodating groove and the extension are arranged on the first rear shell, the first front cover covers the accommodating groove and the extension, the extension is provided with a positioning protrusion, and correspondingly, the first front cover is provided with a positioning groove matched with the positioning protrusion, and the positioning protrusion is matched in the positioning groove.

[0016] As a preferred scheme, the outer periphery of the connecting sleeve is provided with a rotation limiting portion, and correspondingly, the side of the first mounting groove is provided with a rotation limiting groove for inserting the rotation limiting portion, and the rotation of the connecting sleeve is limited in the rotation limiting groove.

[0017] As a preferred scheme, the outer periphery of the push rod is provided with an anti-falling portion, the bottom of the anti-falling portion is movably limited to the top of the end cover, the top end of the second mounting groove is provided with a second resisting edge, and a spring is clamped between the bottom of the second resisting edge and the top of the anti-falling portion.

[0018] As a preferred scheme, the top of the spring and the bottom of the second resisting edge are clamped with a pad.

[0019] As a preferred scheme, the metal shell is made of aluminum alloy material, the connecting sleeve is made of plastic material, and the metal sleeve is made of stainless steel material.

[0020] As a preferred scheme, the metal shell is connected with a Z-axis driving device through a connecting piece, and the Z-axis driving device drives the metal shell to move along the Z-axis.

[0021] As a preferred scheme, the Z-axis driving device comprises a second rear shell, a second motor arranged on the second rear shell, a second vertical lead screw, a second vertical slide rail and a second control panel, the second vertical lead screw is connected to the second motor, the second vertical lead screw, the second vertical slide rail and the second control panel are arranged in the second rear shell from left to right with a certain distance, the second vertical lead screw is provided with a second nut, the second vertical slide rail is provided with a second sliding block, the second nut and the second sliding block are connected with a second linkage plate, and the two ends of the connecting piece are connected to the second linkage plate and the first rear shell respectively.

[0022] Compared with the prior art, the present application has obvious advantages and beneficial effects, specifically, the above technical scheme can know that:

[0023] Mainly, by setting the sealing ring and the first O-ring, the gap between the plunger, the metal sleeve and the connecting sleeve is sealed, two second O-rings are used to seal the gap between the connecting sleeve and the metal shell, and two third O-rings are used to seal the gap between the metal sleeve and the connecting sleeve. The arrangement of the connecting sleeve can avoid the conduction between the metal sleeve and the metal shell, ensure the accuracy of the capacitance detection function, and the metal sleeve includes a cavity and a plug integrally formed at the bottom of the cavity, so that the cavity and the plug do not need to be sealed and spliced, reducing the dead volume of the cavity, avoiding the risk of plug loosening after multiple Tip head insertions, improving the rigidity of the Tip head, making the pipette more miniaturized, and more flexible to use. The three-segment sealing can make the wire pass through the second channel and be directly connected to the metal shell, reducing the length of the capacitance detection assembly, making it more convenient to fix, and the middle part of the connecting sleeve is provided with a third channel communicating with the inside of the connecting sleeve and the first channel. The end of the air pipe away from the air pressure detector is inserted into the first channel, so that the pipette can simultaneously have air pressure detection function and capacitance detection function, and the liquid level detection effect is better. The wall surface of the cavity and the outer periphery of the plunger are provided with a PTFE film to reduce the gap between the cavity and the plunger, reduce the dead volume of liquid suction and discharge, thereby improving the precision and CV value of liquid suction and discharge. PTFE has excellent self-lubricating performance and good biological compatibility.

[0024] In order to more clearly illustrate the structural features and effects of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a perspective view of the preferred embodiment of the present application;

[0026] Figure 2 is a partial assembly view of the preferred embodiment of the present application;

[0027] Figure 3 is an installation schematic view of the connecting sleeve of the preferred embodiment of the present application;

[0028] Figure 4 is a cross-sectional view of the metal shell of the preferred embodiment of the present application;

[0029] Figure 5 is Figure 4 is a partial enlarged view of A in FIG. 8;

[0030] Figure 6 is a schematic view of the splicing state of eight micro pipettes of the preferred embodiment of the present application;

[0031] Figure 7 is another schematic view of the splicing state of eight micro pipettes of the preferred embodiment of the present application.

[0032] Explanation of the drawing:

[0033] 10 metal shell 11 end cover

[0034] 111 first via hole 112 second via hole

[0035] 12 mounting position 121 clamping slot

[0036] 122 taking position 123 mounting column

[0037] 13 first rear shell

[0038] 14 first front cover 141 positioning groove

[0039] 101 accommodating groove 102 extension

[0040] 103 first mounting slot 1031 rotation limiting slot

[0041] 104 second mounting slot 1041 second resisting edge

[0042] 105 first channel 106 second channel

[0043] 107 positioning protrusion 108 first resisting edge

[0044] 20 plunger assembly 21 connecting sleeve

[0045] 211 third channel 212 third mounting slot

[0046] 213 rotation limiting part 22 plunger

[0047] 23 metal sleeve 231 cavity

[0048] 232 plug 30 push rod assembly

[0049] 31 push rod 311 anti-dropping part

[0050] 32 push sleeve 33 spring

[0051] 34 pad 40 driving assembly

[0052] 41 first motor 42 first vertical screw rod

[0053] 421 first nut 43 first vertical sliding rail

[0054] 431 first sliding block 44 first linkage plate

[0055] 50 first control plate 51 air pressure detection assembly

[0056] 511, air pressure detector 512, air pipe

[0057] 52, wire

[0058] 60, Z-axis driving device 61, second rear shell

[0059] 62, second motor 63, second vertical screw rod

[0060] 631, second nut 64, second vertical sliding rail

[0061] 641, second sliding block 65, second control board

[0062] 66, second linkage plate 67, buffer block

[0063] 68, second front shell

[0064] 601, connecting piece 602, first adapter block

[0065] 603, second adapter block 604, U-shaped groove

[0066] 605, inclined surface 606, conical fixing screw

[0067] 70, sealing ring 80, first O-ring

[0068] 90, second O-ring 100, third O-ring

[0069] 110, PTFE film. DETAILED DESCRIPTION

[0070] First of all, it should be noted that in the description of the present application, the terms "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0071] Please refer to Figures 1 to 7 The specific structure of the preferred embodiment of the present application is shown in the drawings, which includes a metal shell 10, a plunger assembly 20, a push rod assembly 30, a driving assembly 40, a first control board 50 and a Z-axis driving device 60.

[0072] The metal shell 10 is provided with a containing groove 101, the bottom wall of the metal shell 10 extends upwardly with an extension 102, the bottom of the bottom wall of the metal shell 10 is provided with a first mounting groove 103 and a second mounting groove 104 which are communicated with the containing groove 101 and the outside of the metal shell 10, the side of the extension 102 is provided with a first channel 105 which is communicated with the first mounting groove 103 and the containing groove 101, the bottom of the bottom wall of the metal shell 10 is provided with an end cover 11, the end cover 11 is provided with a first through hole 111 and a second through hole 112 which are corresponded to the first mounting groove 103 and the second mounting groove 104 respectively, the bottom wall of the metal shell 10 and the end cover 11 are provided with a second channel 106 which is communicated with the containing groove 101 and the first through hole 111;

[0073] As shown in Figure 1 and 2 The containing groove 101 is provided with a mounting position 12 for mounting the first vertical slide rail 43, the mounting position 12 is concavely provided with a clamping groove 121, a plurality of mounting columns 123 which protrude out of the clamping groove 121 are arranged in the clamping groove 121, the first vertical slide rail 43 is clamped in the clamping groove 121 and fixed on the mounting columns 123, the arrangement of the clamping groove 121 and the mounting columns 123 can greatly reduce the installation height of the first vertical slide rail, thereby reducing the overall thickness of the pipette and making it more compact, a plurality of taking positions 122 are arranged on the side of the clamping groove 121, the taking positions 122 are located on the periphery of the mounting columns 123, and the arrangement of the taking positions 122 facilitates the disassembly and assembly of the first vertical slide rail 43.

[0074] The metal shell 10 includes a first rear shell 13 and a first front cover 14 connected to the first rear shell 13, the containing groove 101 and the extension 102 are arranged on the first rear shell 13, the first front cover 14 covers the containing groove 101 and the extension 102, the extension 102 is provided with a positioning protrusion 107, correspondingly, the first front cover 14 is provided with a positioning groove 141 which is matched with the positioning protrusion 107, and the positioning protrusion 107 is adapted to the positioning groove 141; in this embodiment, the metal shell 10 is made of aluminum alloy;

[0075] The first rear shell 13 is concavely provided with a first lead screw mounting position, the first front cover 14 is concavely provided with a second lead screw mounting position which is corresponded to the first lead screw mounting position, the arrangement of the first lead screw mounting position and the second lead screw mounting position can make the size of the metal shell 10 thinner, at present, there are few pipettes which can be spliced with a 9mm spacing in the medical industry, and there are also few devices which separately match the 9mm pipette with the Z-axis driving device 60, the 9mm pipette needs Z-direction movement in many use scenarios, as shown in Figure 6 and Figure 7As shown, eight metal shells 10 can be connected side by side, which can solve the problem of high-precision pipetting of 9mm spacing reagent tip heads in batches.

[0076] As shown in Figure 4 and Figure 5 As shown, the plunger assembly 20 is arranged in the first mounting groove 103, the plunger assembly 20 includes a connecting sleeve 21, a plunger 22, and a metal sleeve 23, the plunger 22 is arranged in the first mounting groove 103, the top of the first mounting groove 103 is provided with a first stop edge 108, the connecting sleeve 21 is made of insulating material, the connecting sleeve 21 is sleeved on the outer periphery of the plunger 22, a sealing ring 70 is arranged between the top of the connecting sleeve 21 and the first stop edge 108, the bottom of the sealing ring 70 extends into the connecting sleeve 21, and a first O-ring 80 is arranged between the inner wall of the connecting sleeve 21 and the bottom of the sealing ring 70, a third channel 211 is arranged in the middle of the connecting sleeve 21, which communicates the inside of the connecting sleeve 21 and the first channel 105, two second O-rings 90 are arranged between the outer periphery of the connecting sleeve 21 and the first mounting groove 103, the two second O-rings 90 are arranged on the upper and lower sides of the third channel 211, respectively, a third mounting groove 212 is arranged in the bottom of the connecting sleeve 21, the end cover 11 fixes the connecting sleeve 21 in the first mounting groove 103 through the metal sleeve 23, the top of the metal sleeve 23 extends into the third mounting groove 212, two third O-rings 100 are arranged between the outer periphery of the metal sleeve 23 and the third mounting groove 212, the metal sleeve 23 includes a cavity 231 and a plug 232 integrally formed at the bottom of the cavity 231, the cavity 231 is sleeved on the outside of the plunger 22, and a PTFE film 110 is arranged between the wall surface of the cavity 231 and the outer periphery of the plunger 22.

[0077] As shown in Figure 3 As shown, the outer periphery of the connecting sleeve 21 is provided with a rotation limiting portion 213, and the side of the first mounting groove 103 is provided with a rotation limiting groove 1031 for inserting the rotation limiting portion 213, and the rotation of the connecting sleeve 21 is limited in the rotation limiting groove 1031; in this embodiment, the connecting sleeve 21 is made of plastic material, and the metal sleeve 23 is made of stainless steel.

[0078] As shown in Figure 4 and Figure 5 As shown, the push rod assembly 30 is arranged in the second mounting groove 104, the push rod assembly 30 includes a push rod 31 and a push sleeve 32 connected to the push rod 31, the push rod 31 is arranged in the second mounting groove 104, and the push sleeve 32 is sleeved on the outer periphery of the metal sleeve 23.

[0079] Specifically, the outer periphery of the push rod 31 is provided with an anti-dropping part 311, the bottom of the anti-dropping part 311 is limitedly arranged on the top of the end cover 11, the top end of the second mounting groove 104 is provided with a second resisting edge 1041, and the bottom of the second resisting edge 1041 and the top of the anti-dropping part 311 are clamped with the spring 33.

[0080] Preferably, the top of the spring 33 and the bottom of the second resisting edge 1041 are clamped with the pad 34.

[0081] The driving assembly 40 is arranged in the accommodating groove 101, and is used to drive the push rod 31 and the plunger 22 to move up and down. The first control plate 50 is arranged in the accommodating groove 101 and located beside the first channel 105. The first control plate 50 is provided with an air pressure detection assembly 51 and a capacitance detection assembly. The air pressure detection assembly 51 comprises an air pressure detector 511 and an air pipe 512 connected to the air pressure detector 511. The end of the air pipe 512 away from the air pressure detector 511 is inserted into the first channel 105. The capacitance detection assembly can be integrated on the first control plate. The capacitance detection assembly comprises a wire 52 connected to the first control plate 50. The end of the wire 52 away from the first control plate 50 is fixed to the metal sleeve 23 through the second channel 106.

[0082] After the TIP head with the conductive function is installed on the plug 232 of the metal sleeve 23, when the TIP head with the conductive function contacts the reagent, the capacitance value between the wire 52 and the first control plate 50 increases. After the first control plate 50 reads and identifies the changed capacitance value, whether it is an effective capacitance value is determined according to the preset capacitance value comparison. If it is, it is determined that the TIP head contacts the reagent liquid surface, and feedback is given to the main control part. The main control MCU takes it as the starting condition of liquid suction and other actions.

[0083] Specifically, referring to FIGS. 1, 2 and 3, Figure 2 and Figure 4 The driving assembly 40 comprises a first motor 41, a first vertical lead screw 42 and a first vertical sliding rail 43. The first vertical lead screw 42 is connected to the first motor 41. The first vertical lead screw 42, the first vertical sliding rail 43 and the first control plate 50 are arranged in the accommodating groove 101 from left to right with a certain interval. The first vertical lead screw 42 is provided with a first nut 421. The first vertical sliding rail 43 is fixed in the clamping groove 121. The first vertical sliding rail 43 is provided with a first sliding block 431. The first nut 421 and the first sliding block 431 are connected with a first linkage plate 44. The top of the plunger 22 is connected to the first linkage plate 44. The top of the push rod 31 can abut against the bottom of the first linkage plate 44.

[0084] The Z axial driving device 60 is connected with the metal shell 10 through a connecting piece 601, and drives the metal shell 10 to move along the Z axis direction;

[0085] Referring to Figure 2 As shown in the drawings, the Z axial driving device 60 comprises a second rear shell 61, a second motor 62, a second vertical lead screw 63, a second vertical sliding rail 64 and a second control plate 65 arranged on the second rear shell 61, the second vertical lead screw 63 is connected with the second motor 62, the second vertical lead screw 63, the second vertical sliding rail 64 and the second control plate 65 are arranged in the second rear shell 61 from left to right with a certain interval, a second nut 631 is arranged on the second vertical lead screw 63, a second sliding block 641 is arranged on the second vertical sliding rail 64, the second nut 631 and the second sliding block 641 are connected with a second linkage plate 66, and two ends of the connecting piece 601 are connected with the second linkage plate 66 and the first rear shell 13 respectively; wherein, a second front shell 68 covering the second motor 62, the second vertical lead screw 63, the second vertical sliding rail 64 and the second control plate 65 is arranged on the front side of the second rear shell 61, and the second motor 62 is a hollow cup motor, which is small in structure and beneficial to splicing;

[0086] The connecting piece 601 comprises a first adapter block 602 connected with the second linkage plate 66 and a second adapter block 603 connected with the first rear shell 13, the first adapter block 602 is provided with a U-shaped groove 604, the second adapter block 603 is clamped in the U-shaped groove 604, the top of the second adapter block 603 is provided with an inclined surface 605, and a conical fixing screw 606 is arranged on the first adapter block 602 and abuts against the inclined surface 605, so that the second adapter block 603 is fixed in the U-shaped groove 604;

[0087] Preferably, the top of the bottom wall of the second rear shell 61 is provided with a buffer block 67, and the second linkage plate 66 can abut against the buffer block 67.

[0088] The cooperation of the first vertical lead screw and the first vertical sliding rail and the cooperation of the second vertical lead screw and the second vertical sliding rail can eliminate the serious problem of deflection of the plunger when the plunger is driven to suck and discharge liquid by the first vertical sliding rail, and can ensure the accuracy of movement when the connecting piece is driven to move along the Z axis direction by the second vertical lead screw, and the lead screw can be selected as a ball screw with higher transmission efficiency and accuracy.

[0089] The design focus of the application is:

[0090] Its main, by setting with sealing ring and first O ring, used to seal the gap between the plunger, metal sleeve, connecting sleeve, two second O ring, used to seal the gap between the connecting sleeve and the metal shell, two third O ring, used to seal the gap between the metal sleeve and the connecting sleeve, the setting of the connecting sleeve, can avoid the metal sleeve and metal shell conductive, ensure that will not affect the accuracy of the capacitance detection function, and the metal sleeve includes cavity and a plug integrally formed on the bottom of the cavity, so that the cavity and the plug without sealing and splicing, reduce the dead volume of the cavity, can avoid the risk of the plug loose after multiple Tip head, improve the rigidity of the Tip head, make the pipette more miniaturization, use will be more flexible, with three sealing can make the wire through the second channel directly connected to the metal shell, reduce the length of the capacitance detection component size, fixed more convenient, the middle part of the connecting sleeve is provided with a third channel which is communicated with the first channel in the connecting sleeve, the end of the air pipe away from the air pressure detector is inserted into the first channel, so that the pipette can have air pressure detection function and capacitance detection function, the liquid level detection effect is better; And, the wall of the cavity and the outer periphery of the plunger are provided with PTFE film, which is used to reduce the gap between the cavity and the plunger, reduce the dead volume of suction and discharge, so as to improve the precision and CV value of suction and discharge, the self-lubricating performance of PTFE is good, and it has good biological compatibility.

[0091] The above is only the preferred embodiment of the present application, not any limitation on the technical scope of the present application, so any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical scheme of the present application.

Claims

1. A miniature pipette that simultaneously possesses both pneumatic pressure detection and capacitance detection functions, characterized in that, The utility model relates to a kind of push rod assembly and drive assembly, including: Metal shell is arranged with accommodating groove in the metal shell, the bottom wall of the metal shell extends with extension, the bottom of the bottom wall of the metal shell is opened with first installation slot, second installation slot corresponding to extension upwards, the side of the extension is opened with first passageway connecting first installation slot and accommodating groove, the bottom of the bottom wall of the metal shell is provided with end cap, the end cap is provided with first via hole, second via hole corresponding to first installation slot, second installation slot, the bottom wall of the metal shell and end cap are opened with second passageway connecting accommodating groove and first via hole together; Plunger assembly, the plunger assembly is set to first installation slot, the plunger assembly includes connecting sleeve, plunger, metal sleeve, the plunger is worn in first installation slot, the top of the first installation slot is provided with first resistance, the connecting sleeve is of insulating material, the connecting sleeve is sleeved on the outer periphery of plunger, the top of the connecting sleeve and first resistance are clamped with sealing ring, the bottom of the sealing ring is inserted into connecting sleeve, and first O-ring is clamped between the inner wall of connecting sleeve, the middle part of the connecting sleeve is opened with third passageway connecting the inside of connecting sleeve and first passageway, the outer periphery of the connecting sleeve and first installation slot are clamped with two second O-rings, and two second O-rings are located on the upper and lower sides of third passageway respectively, the bottom of the connecting sleeve is opened with third installation slot upwards, the end cap is fixed in first installation slot by metal sleeve with connecting sleeve, the top of the metal sleeve is inserted into third installation slot, the outer periphery of the metal sleeve and third installation slot are clamped with two third O-rings, the metal sleeve includes cavity and plug integrally formed on the bottom of cavity, the cavity is sleeved on the outside of plunger, and PTFE film is arranged between the wall surface of cavity and the outer periphery of plunger; Push rod assembly, the push rod assembly is set to second installation slot, and the push rod assembly includes push rod and push sleeve connected to push rod, the push rod is worn in second installation slot, and the push sleeve is sleeved on the outer periphery of metal sleeve; Drive assembly, the drive assembly is arranged in accommodating groove, and the drive assembly is used to drive push rod and plunger to move up and down; First control board, the first control board is arranged in accommodating groove, and is located on the side of first passageway, the first control board has air pressure detection assembly and electric capacity detection assembly, the air pressure detection assembly includes air pressure detector and air pipe connected to air pressure detector, the end of the air pipe away from air pressure detector is inserted into first passageway, the electric capacity detection assembly includes lead wire connected to first control board, and the end of the lead wire away from first control board is fixed to metal sleeve through second passageway.

2. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 1, characterized in that: The driving assembly comprises a first motor, a first vertical screw rod, and a first vertical sliding rail, the first vertical screw rod is connected to the first motor, the first vertical screw rod, the first vertical sliding rail, and a first control plate are arranged in the accommodating groove from left to right in sequence at intervals, a first nut is arranged on the first vertical screw rod, a first sliding block is arranged on the first vertical sliding rail, the first nut and the first sliding block are connected to a first linkage plate together, the top of the plunger is connected to the first linkage plate, and the top of the push rod can abut against the bottom of the first linkage plate.

3. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 2, characterized in that: The accommodating groove is provided with a mounting position for mounting the first vertical sliding rail, the mounting position is concavely provided with a clamping groove, a plurality of mounting columns outside the clamping groove are arranged in the clamping groove, and the first vertical sliding rail is clamped in the clamping groove and fixed on the mounting columns.

4. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 1, characterized in that: The metal shell comprises a first rear shell and a first front cover connected to the first rear shell, the accommodating groove and the extension part are arranged on the first rear shell, the first front cover covers the accommodating groove and the extension part, the extension part is provided with a positioning convex part, correspondingly, the first front cover is provided with a positioning groove matched with the positioning convex part, and the positioning convex part is matched in the positioning groove.

5. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 1, characterized in that: The outer periphery of the connecting sleeve is provided with a rotation limiting part, correspondingly, a rotation limiting groove for inserting the rotation limiting part is arranged beside the first mounting groove, and rotation of the connecting sleeve is limited in the rotation limiting groove.

6. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 1, characterized in that: The outer periphery of the push rod is provided with an anti-falling part, the bottom of the anti-falling part is movably limited to the top of the end cover, the top end of the second mounting groove is provided with a second blocking edge, and a spring is clamped between the bottom of the second blocking edge and the top of the anti-falling part.

7. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 6, characterized in that: The top of the spring and the bottom of the second blocking edge are clamped between the top of the second blocking edge and the bottom of the second blocking edge.

8. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 1, characterized in that: The metal shell is made of aluminum alloy material, the connecting sleeve is made of plastic material, and the metal sleeve is made of stainless steel material.

9. The micro pipette with both air pressure detecting function and capacitance detecting function according to any one of claims 1 to 8, characterized in that: The metal shell is connected with a Z-axis driving device through a connecting piece, and the Z-axis driving device drives the metal shell to move along the Z-axis.

10. The micro pipette with both air pressure detecting function and capacitance detecting function according to claim 9, characterized in that: The Z-axis driving device comprises a second rear shell, a second motor, a second vertical screw rod, a second vertical sliding rail, and a second control plate arranged on the second rear shell, the second vertical screw rod is connected to the second motor, the second vertical screw rod, the second vertical sliding rail, and the second control plate are arranged in the second rear shell from left to right in sequence at intervals, a second nut is arranged on the second vertical screw rod, a second sliding block is arranged on the second vertical sliding rail, the second nut and the second sliding block are connected to a second linkage plate together, and the two ends of the connecting piece are connected to the second linkage plate and the first rear shell respectively.

Images