RU2782876C1 - Valveless diaphragm microfluidic pump - Google Patents

Abstract

FIELD: medical equipment.

SUBSTANCE: invention relates to medical equipment, namely to medical pumping devices for pumping small amounts of liquid, and can be used as a portable wearable device for dosed drug delivery or a portable laboratory-on-a-chip. Valveless membrane microfluidic pump contains a housing, the walls of which are formed by parts rigidly connected to each other, inlet and outlet ports located in the first part of the housing, inlet and outlet hydrodiodes, a pump chamber, seals, an actuator chamber with an actuator made of an ionic polymer-metal composite inside, which is console element. One end of the actuator is connected to a working membrane made of an elastic material and located between the pump and actuator chambers, and the other end is rigidly fixed between the electrodes connected to the wires that can be connected to the generator. The inlet and outlet hydrodiodes are located in the first body part, the pumping chamber is formed by the internal cavity of the first body part and the working membrane. Between the second and third parts of the body there is a compensating membrane made of an elastic material, and the actuator chamber is formed by the internal cavity of the second part of the body, the working and compensating membranes, and the internal cavity of the third part of the body and the compensating membrane form an air chamber with holes. In a valveless diaphragm microfluidic pump, all body parts can be 3D printed with photopolymer resin.

EFFECT: increasing the reliability and service life of a valveless membrane MFP based on the IPMC actuator, as well as increasing the fluid flow rate.

2 cl, 7 dwg

Description

The invention relates to medical pumping devices for pumping small amounts of liquid and can be used as a portable wearable device for dosed drug delivery or a portable laboratory-on-a-chip.

Known valveless two-chamber microfluidic pump (MPP) based on an actuator made of ionic polymer-metal composite (IPMC-actuator) as a membrane (CN203272085U, publ. two primary pumping chambers. Between the IPMK-actuator and each part of the housing there is a seal that follows the contour of the walls of the housing parts. Each body part has two holes on opposite walls of different diameters. A part with a hydrodiode with a larger hole inside the housing is installed in a hole with a larger diameter, and a part with a hydrodiode with a smaller hole inside the housing is installed in a hole with a smaller diameter. Parts with inlet and outlet ports are installed to opposite holes of parts with hydrodiodes. Connections of all parts are made using sealing material. Inside each primary pumping chamber, the holes of parts with hydrodiodes are connected by a secondary pumping chamber made of elastic material. Both primary pumping chambers are filled with a liquid for impregnating the IPMK-actuator. Under the action of an alternating control voltage, the IPMK actuator is deformed, creating an increased pressure in one primary pumping chamber and a reduced pressure in the other primary pumping chamber. The change in pressure in the primary pumping chambers results in a change in the volume of the secondary pumping chambers due to the elasticity of the pumping chambers, which contributes to the creation of a flow of working fluid through the secondary pumping chambers. The straightening of the flow of the working fluid is carried out by four parts with hydrodiodes. The presence of two secondary pumping chambers, alternately operating in pumping mode and pumping mode, makes it possible to double the volume of the pumped working fluid.

The disadvantages of the known valveless two-chamber MPN based on the IPMK-actuator as a membrane are low reliability and complexity of assembly, due to the large number of parts and connecting assemblies that require additional sealing.

Known piston MPN based on IPMK-actuators as membranes (CN203272034U, publ. 11/06/2013), the design of which contains: the base plate of the body with holes in which parts with inlet and outlet ports are installed, inside which spring valves are installed; the main part of the body, mounted on the base plate of the body with a sealant laid along the contour of the outer walls of the main part of the body, in which there are cavities that form the first, second and third pump chambers with the base plate of the body, and cavities for the IPMK actuator (horizontal partitions separating the cavity under the IPMK-actuator and the pumping chamber, have a hole into which the piston rod is inserted; vertical partitions between the first, second and third pumping chambers have holes through which the fluid flows); first, second and third pistons located in the first, second and third pumping chambers, respectively; rods of the first, second and third pistons, which are connected to the first, second and third IPMK-actuators, rigidly fixed to the main body part along the contour of cutouts for cavities for IPMK-actuators. When a control voltage is applied to the first, second and third IPMK actuators with a given delay, the IPMK actuators begin to deform and move the pistons, following the movement of which the volume of the pump chambers and the pressure in the pump chambers change. The alternating change in pressure in the pumping chambers creates a fluid flow from the inlet port to the outlet port, and the straightening of the flow is provided by spring valves, the stroke of which is determined by the direction of the cone-shaped section of the parts with the inlet and outlet ports.

The disadvantages of the well-known piston MPF based on IPMK-actuators as membranes are: a reduced degree of deformation of IPMK-actuators, due to the additional friction force of the pistons against the walls of the pumping chambers and increasing with time of operation and the high gravity acting on the pistons; the complexity of manufacturing the structure and the decrease in its reliability, due to the presence of many parts of the nodes connecting them, as well as the presence of spring valves and pistons that wear out over time; rapid deterioration of pump performance due to the degradation of the IPMC actuator due to the loss of the liquid impregnating it over time.

Known valveless elastic MPN based on IPMC actuators (CN109899272A, publ. 06/18/2019), the design of which contains: the main part of the body in the form of a silica gel plate with a through cavity, input and output hydrodiodes and input and output ports; a pumping chamber formed by the cavity of the main body part and elastic membranes on both sides, to which the first ring-shaped electrodes, IPMC-actuators in the form of a disk with a hole in the center in the form of petals and the second electrodes in the form of ring shape; polydimethylsiloxane plates, which cover the structure described above on both sides. The applied alternating voltage to the electrodes leads to deformation of the IPMC actuators, which deform the elastic membranes, thereby changing the volume of the pumping chamber and the pressure in the pumping chamber and creating a flow of working fluid through the pumping chamber.

The disadvantages of the known valveless elastic MPN based IPMK-actuators are: the complexity of manufacturing IPMK-actuators, due to the special form of IPMK-actuators in the form of a disk with a hole in the form of petals; rapid deterioration of the pump performance due to the wear of IPMC actuators due to the loss of the liquid impregnating them over time.

The closest to the claimed technical solution in terms of technical essence and the achieved technical result is a valveless membrane MPN based on IPMC Actuator (V.E. Kalyonov, Y.D. Orekhov, A.N. Shahabdin, A.P. Broyko, D.O. Testov. Valveless Microfluidic Pump Based on IPMC Actuator for Drug Delivery // 2020 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus), 2020, pp. 1531–1534, https://ieeexplore.ieee.org/document/9039419). The body of the MPF consists of four parts made of polycarbonate and polymethyl methacrylate. The first body part contains inlet and outlet ports that can be connected to external tanks. The second part of the housing contains the input and output hydrodiodes. The cavity located in the third part of the housing, together with the glued latex membrane, forms the pumping chamber. The cavity located in the fourth part of the housing, together with the glued latex membrane, forms an actuator chamber. The fourth part of the housing has a channel for filling the actuator chamber with water, into which the IPMC actuator is immersed, one end of which is rigidly fixed between the electrodes connected to the wires, which makes it possible to overcome the problem of IPMC actuator dehydration. A piece of double-sided adhesive tape is placed under the latex membrane in the center where the other end of the IPMC actuator is connected to the latex membrane. For sealing, rubber seals are laid along the contour. Thus, the MFN can operate continuously.

The disadvantage of the known valveless membrane MPN based on the IPMC actuator is the change in the volume of the actuator chamber and the pressure in the actuator chamber when the latex membrane is deformed under the action of the IPMC actuator, which leads to a decrease in the deflection amplitude of the IPMC actuator, thereby reducing the reliability and service life of the MPN, as well as the fluid flow rate.

The technical problem to be solved by the claimed invention is to increase the reliability and service life of a valveless membrane MPN based on the IPMC actuator, as well as to increase the fluid flow rate.

The stated technical problem is solved by the fact that in a valveless membrane microfluidic pump containing a housing, the walls of which are formed by rigidly interconnected parts, inlet and outlet ports located in the first part of the housing, inlet and outlet hydrodiodes, a pump chamber, seals, an actuator chamber with IPMK- actuator inside, one end of which is connected to the working membrane located between the pump and actuator chambers, and the other end is rigidly fixed between the electrodes connected to the wires, configured to connect to the generator, the input and output hydrodiodes are located in the first part of the housing, the pump chamber is formed the internal cavity of the first part of the body and the working membrane, and between the second and third parts of the body there is a compensating membrane, and the actuator chamber is formed by the internal cavity of the second part of the body, the working and compensating membranes, and the internal cavity of the third part of the body and the compensating membrane form an air chamber with holes.

The formation of the volume of the actuator chamber between the elastic membranes (working and compensating) provides a constant volume of the actuator chamber and a constant pressure in the actuator chamber due to the fact that when the working membrane is deformed under the action of the IPMC actuator, the compensating membrane is deformed similarly to the working one due to its elasticity. Maintaining a constant volume of the actuator chamber and a constant pressure in the actuator chamber makes it possible to stabilize the deflection amplitude of the IPMC actuator, which increases the reliability of operation and service life of the MFP, as well as the fluid flow rate.

The set of features according to claim 2, which characterizes a valveless membrane microfluidic pump, in which all body parts are made by 3D printing with photopolymer resin, reduces the overall dimensions of the pump, since this manufacturing method makes it possible to manufacture small parts and structures on them.

The essence of the invention is illustrated by the figures, where

in fig. 1 shows the design of the MPN;

in fig. 2 shows a drawing of the MFN in cross section;

in fig. 3 shows a drawing of the MFN in a longitudinal section;

in fig. 4 shows the calculated geometry of the input and output hydrodiodes;

in fig. 5 shows the dependence of the water flow rate on the frequency of the sinusoidal control voltage;

in fig. 6 shows the dependence of the water flow rate on the amplitude of the sinusoidal control voltage at a frequency of 0.4 Hz;

in fig. 7 shows the dependence of the back pressure when pumping water on the amplitude of the sinusoidal control voltage at a frequency of 0.4 Hz.

The valveless membrane MPF (Fig. 1, Fig. 2, Fig. 3) contains: the first part 1 of the body, the inner cavity of which, together with the working membrane 2, forms a pumping chamber 3; input and output hydrodiodes 4 and 5, input and output ports 6 and 7; the second part 8 of the housing, the internal cavity of which, together with the working 2 and compensating 9 membranes, forms an actuator chamber 10, inside which the IPMK-actuator 11 is located, which is a cantilever element, one end of which is connected to the working membrane 2 using a loop 12, and the other - rigidly fixed between electrodes 13 and 14 connected to wires 15; the third part 16 of the body, the inner cavity of which together with the compensating membrane 9 forms an air chamber 17 with holes 18; seals 19 and 20.

IPMK-actuator 11 is a three-layer structure consisting of a porous polymeric ion-exchange membrane and metal electrodes deposited on its surface.

For the manufacture of body parts 1, 8 and 16, it is preferable to use additive technologies using photopolymer resin as a material for 3D printing.

The optimal solution for MFP operation is the use of working and compensating membranes 2 and 9 without tension. The material for the working and compensating membranes 2 and 9 is an elastic material, such as latex rubber.

The IPMC actuator 11 is connected to the working membrane 2 by gluing a plastic loop 12 to the working membrane 2, into which the IPMC actuator 11 is inserted.

The actuator chamber 10 is filled with water at the pump assembly stage.

As the material of the seals 19 and 20, an elastic elastic material, such as rubber based on isoprene rubber, can be used.

The electrodes 13 and 14 have a transverse bend with a semi-circular cross section, into which the core of the wire 15 is inserted. This design makes it possible to make the electrodes 13 and 14 movable in order to simplify the installation of the IPMC actuator 11 between them. Also, each electrode 13 and 14 has an area that occupies about a third of the area of the electrodes of the IPMC actuator 11. This contributes to a better distribution of the electric potential over the electrodes of the IPMC actuator 11 and, as a result, an increase in the deviation amplitude of the IPMC actuator 11.

The air chamber 17, formed by the internal cavity of the third body part 16 and the compensating membrane 9, allows the compensating membrane 9 to freely bend downwards along the axis 21, and the holes 18 ensure a constant pressure equal to the pressure in the external environment in the air chamber 17.

The device works as follows.

The electrodes 13 and 14 are configured to be connected by wires 15 to a sinusoidal voltage generator 22, from which a sinusoidal control voltage is supplied. Fixed between electrodes 13 and 14, the IPMC actuator 11 bends under the action of a sinusoidal control voltage in such a way that the movable part of the IPMC actuator 11, connected to the working membrane 2, moves periodically along the axis 21 in the direction down and up in accordance with the frequency of the sinusoidal control voltage. Following the moving part of the IPMC actuator 11, the working membrane 2 connected to it is deformed, which leads to a periodic change in pressure in the pump chamber 3. The change in pressure in the pump chamber 3 creates a fluid flow through the inlet port 6, the pump chamber 3 and the outlet port 7. Straightening the liquid flow is carried out by the input and output hydrodiodes 4 and 5.

An increase in voltage between electrodes 13 and 14 so that the variable potential of electrode 13 turns out to be negative relative to the constant potential of electrode 14 leads to the fact that the IPMC actuator 11 bends and its movable part, connected to the working membrane 2, moves down along axis 21. Bending working membrane 2 down along the axis 21 leads to an increase in the volume of the pump chamber 3, which contributes to a decrease in pressure in the pump chamber 3 and pumping fluid into the pump chamber 3, which corresponds to the power supply of the pump. A larger volume of liquid enters the pumping chamber 3 through the inlet hydrodiode 4 than through the outlet hydrodiode 5.

An increase in voltage between electrodes 13 and 14 so that the variable potential of electrode 13 turns out to be positive relative to the constant potential of electrode 14 leads to the fact that the IPMC actuator 11 and its movable part connected to the working membrane 2 move upward along the axis 21. The bending of the working membrane 2 upwards along axis 21 leads to a decrease in the volume of the pump chamber 3, which contributes to an increase in pressure in the pump chamber 3 and displacement of fluid from the pump chamber 3, which corresponds to the pumping mode of the pump. Through the inlet hydrodiode 4, a smaller volume of liquid leaves the pumping chamber 3 than through the outlet hydrodiode 5.

The bending of the working membrane 2 leads to the bending of the compensating membrane 9, which makes it possible to preserve the volume of the actuator chamber 10 and increase the amplitude of the deflection of the IPMC actuator 11.

Changing the pump performance is carried out in two ways: by decreasing or increasing the frequency of the sinusoidal control voltage in the range of 0 ... 2 Hz; decrease or increase in the amplitude of the sinusoidal control voltage in the range of 0 ... 10 V.

Device implementation example.

An 8 × 3 × 0.3 mm structure consisting of an MF-4SK membrane and platinum electrodes deposited on the membrane surface by chemical reduction from a platinum salt solution was used as the IPMC actuator 11.

Parts 1, 8 and 16 of the body are made by 3D printing with photopolymer resin.

Used working and compensating membranes 2 and 9 without tension, made of latex rubber.

Used seals 19 and 20, made of rubber based on isoprene rubber with a thickness of 0.8 mm.

The overall dimensions of the proposed valveless membrane MPN are 19 × 20 × 8 mm.

The input and output hydrodiodes 4 and 5 have the following geometric characteristics (Fig. 4): r = 0.15 mm, α = 9.46°, R = 0.35 mm, L = 1.2 mm, where r is the radius of the small section, α is the opening angle, R is the radius of the large section, L is the longitudinal length.

Studies of the water flow rate and back pressure were carried out when a sinusoidal control voltage was applied in the frequency range of 0.1 ... 1.6 Hz and in the amplitude range of 1 ... 10 V.

From FIG. 5 shows that the maximum water flow rates are achieved at a frequency of 0.4 Hz for both amplitudes of the sinusoidal control voltage (5 V - curve 23, 8 V - curve 24). It can also be seen that as the amplitude of the sinusoidal control voltage increases, the flow rate increases non-linearly when operating at the same frequencies. With a further increase in frequency, the flow rate decreases, and the higher the amplitude of the sinusoidal control voltage, the faster the flow rate decreases.

From FIG. It can be seen from Fig. 6 that the water flow rate increases with the increase in the amplitude of the sinusoidal control voltage, which is due to the fact that at a higher applied voltage, the IPMC actuator 11 bends more and displaces a larger volume of water from the pump chamber 3.

From FIG. 7 it can be seen that the back pressure during water pumping increases with the increase in the amplitude of the sinusoidal control voltage, which is due to the fact that at a higher applied voltage, the IPMC actuator 11 presses on the working membrane 2 with greater force.

As a result of the studies, it was found that the maximum flow rate of water, which the proposed MPN develops, is 7.18 µl/s with a sinusoidal control voltage amplitude of 10 V and a frequency of 0.4 Hz, while the prototype is characterized by a maximum speed of 5.33 µl/s. The maximum back pressure created by the proposed MPF when pumping water is 531 Pa.

Claims (2)

1. A valveless membrane microfluidic pump, containing a housing, the walls of which are formed by rigidly interconnected parts, inlet and outlet ports located in the first part of the housing, inlet and outlet hydrodiodes, a pump chamber, seals, an actuator chamber with an actuator made of an ionic polymer-metal composite inside , which is a cantilever element, one end of which is connected to the working membrane located between the pump and actuator chambers, and the other end is rigidly fixed between the electrodes connected to the wires, made with the possibility of connecting to the generator, characterized in that the input and output hydrodiodes are located in of the first part of the housing, the pumping chamber is formed by the internal cavity of the first part of the housing and the working membrane, and between the second and third parts of the housing there is a compensating membrane, and the actuator chamber is formed by the internal cavity of the second part of the housing, the working and compensating membranes, and the outer the morning cavity of the third body part and the compensating membrane form an air chamber with holes. 2. Valveless diaphragm microfluidic pump according to claim 1, characterized in that all parts of the body are made by 3D printing with photopolymer resin.

Images