Technical Field of the Invention

The invention is related to a cam that is controlled by a power supply and a control valve for microfluidic systems formed of two or more channels, that compresses by means of the cam, the channels in order to prevent flow through said channels depending on the shape of the cam using a power supply, thereby allowing flow only through the desired channel.

Known State of the Art (Prior Art)

In microfluidic systems, the valves are used as a flow control element that allows or prevents flow by opening and closing conditionally. The valves in microfluidic systems, can be operated as pneumatic, magnetic or electrostatic valves. In the present microfluidic systems, valves operating on the principle of compression of elastic ducts or hoses in order to cut and control the flow of liquid have been provided.

In the patent numbered “US-8656958-B2”, when the air pressure is applied to one of the two channels that are placed on top of each other and are separated by a silicone elastomeric membrane; the membrane between the channels bends towards the other channel where the flow is carried out, and it prevents the flow. These types of valves are preferred as they can operate, even at high flow pressures. However in order for these valves to be able to operate, an air pressure is required and also an external solenoid valve is required in order to control said air pressure channels. This condition, makes it difficult to control the valve.

In the patent application numbered ΈR 2 775 183 A2’ a wall is located between the two flow lines and a polymer membrane is provided in order to enclose this wall and the flow lines. When the protrusion on the rotary actuating member is positioned to be aligned with the wall on the membrane, the membrane does not bend and flow is not provided between the two flow lines. However when the rotary actuating member is positioned somewhere else, other than the wall, the membrane bends upwards because of the fluid pressure and flow can be provided between the flow lines.

In the patent application numbered ‘GB 2555816 A’ a wall located inside the micro channel and an elastic membrane located on this wall has been provided. When the membrane is lifted up with any kind of actuator (such as a pin), flow is carried out from one side of the wall to the other.

In valves having a membrane, the requirement of such membranes makes it difficult to produce the valves. In the patent application numbered ‘WO 201006255 A the flow is cut off or controlled by means of a piston/pin instead of a membrane. In such a case the actuating piston/pin comes in contact with the working fluid. This leads to contamination of the piston/pin or the working fluid.

On the other hand, in most of the present systems a single valve controls a single channel; it is not possible to control a plurality of flow channels using a single valve. Moreover, the number of flow channels cannot be increased according to demand.

Brief Description of the Invention and its Aims

The present invention has been developed in order to eliminate the disadvantages mentioned above and is related to a cam controlled valve system for microfluidic systems in order to provide new advantages to the related technical field.

The preferred embodiment of the invention is formed of a pair of channels that have been positioned parallel to each other, a cam, and fluid(s) that pass through the pair of channels that have been positioned parallel to each other and the invention has been developed to control two flow channels. Another preferred embodiment of the invention is formed of a pair of elastomeric channels that have been positioned parallel to each other, a rotation element, two cams, and fluid(s) that pass through the pair of elastomeric channels that have been positioned parallel to each other and the invention has been developed to control four different flow channels.

An aim of the invention is to be able to increase as much as possible, the number of flow channels that are desired to be controlled. In the present system the number of flow channels can be increased according to the requirement of the system, by varying the geometry and number of cams available on the rotation element. Another aim of the invention is to prevent contamination at the valve region. In the invention the flow channels do not intersect with each other at the valve region. Due to this reason fluids inside the flow channels do not mix with each other. Moreover, the cam does not come into contact with the fluid. Thereby the risk of contamination is eliminated. The subject matter of the invention is a valve for microfluidic systems, by which a plurality of flow channels can be controlled at the same time via cam control and by which contamination can be prevented.

Brief Description of the Figures

The figures that have been illustrated in order to further describe the cam controlled valve for microfluidic systems that has been developed by the present invention have been disclosed below.

Figure 1 (A, B) - Schematic view illustrating the cutting off of the flow of the single elastomeric channel by compression of the cam control valve

Figure 2 (A, B) - Schematic view illustrating the cutting off of the flow of the two elastomeric channels by compression of the cam control valve

Figure 3 (A, B) - Schematic view of the configuration of the cam control valve within the elastomeric microfluidic chip.

Figure 4 - Schematic view of the configuration of the cam control valve in the microfluidic chip, for controlling the two elastomeric channels that provide flow Figure 5 - Schematic view of the cam control valve that is driven using a servo motor

Figure 6 - Photo of the cam control valve that is driven using a servo motor

Figure 7 - Graphic showing the leakage rate at various flow rates of the cam control valve that is driven using a servo motor

Figure 8 - schematic view of the cam control valve that controls flow in four elastomeric channels by using a plurality of cams

Figure 9 - schematic view of the cam control valve that controls flow in three elastomeric channels by changing the cam profile Definitions of the aspects and parts that form the invention

The parts and aspects provided in the figures that have been prepared in order to further describe the cam control valve for microfluidic systems developed by means of the invention have each been numbered and the references of each number has been listed below.

1- (A, B, C, D) Elastomeric channel

2- (A, B) Liquid

3- Flow

4- (A, B) Cam

5- Shaft

6- Rigid support

7- Microfluidic chip

8- Space

9- (A, B) Port

10- Downstream flow

11- Upstream flow

12- Thick wall

13- Servo Motor a- (1, 2, 3) Rotation angle

Detailed Description of the Invention

The flow (3) of the liquid (2) flowing through any elastomeric channel (1) can be cut off, by the rotation of the cam (4) that has been placed outside the channel with the help of a shaft (5) that is located in the axis of rotation of the cam and accordingly the compression of the elastomeric channel (1). The flow (3) through the elastomeric channel (1) at a certain rotation angle (al) of the cam (4) is shown in Figure 1A and the cut off of the flow, by the compression of the elastomeric channel (1) at another rotation angle (a2) of the cam (4) is shown in Figure IB. In order for the elastomeric channel (1) to be able to be compressed by the cam (4), a rigid support (6) at the opposite end of the cam (4) and the elastomeric channel (1) is required.

Based on this principle, in the case that the elastomeric channels (1 A, IB) are placed on both sides of the cam (4), and the cam (4) is positioned at the first rotation angle (al), the first elastomeric channel (1A) is closed and the second elastomeric channel (IB) is opened, thereby it is possible for the fluid inside the second elastomeric channel (1 A) to be allowed to flow (3), and the liquid inside the first elastomeric channel (1 A) to be prevented from flowing (Figure 2A). Similarly, in the case that the cam (4) is positioned at the second rotation angle (a2), the second elastomeric channel (IB) is closed and the first elastomeric channel (1A) is opened, thereby it is possible for the liquid inside the first elastomeric channel (1A) to be allowed to flow (3), and the liquid inside the second elastomeric channel (IB) to be prevented from flowing (Figure 2B)

In an embodiment of the invention that is based on the principle illustrated in Figure 2, the first and the second elastomeric channel (1A, IB) has been placed on an elastomeric microfluidic chip (7) that has been produced from polydimethylsiloxane (PDMS) (Figure 3). A cam (4) connected to a shaft (5) has been placed into the space (8) that has been defined between the elastomeric channels (1 A, IB) located on the microfluidic chip (7). It is possible to cut off the flow of the first fluid (2A) in the first elastomeric channel (1 A) by compressing the first elastomeric channel (1A) or the second elastomeric channel (IB) in connection with the rotation angle of the cam (a) or the flow of the second fluid (2B) inside the second elastomeric channel (IB) by compressing the second elastomeric channel (IB) respectively. In this embodiment, while the first fluid (2A) is transferred into the first elastomeric channel (1A) via the first port (9A), the second fluid (2B) is transferred into the second elastomeric channel (1A) via the second port (9A). In this case, the flow is transferred in a controlled manner from the first and the second elastomeric channels (1A, IB) downstream (10) of the microfluidic chip (7) and can be used for any process downstream (Figure 3A). Similarly the first fluid (2A) that is obtained as a result of any of the processes carried out upstream (11) of the microfluidic chip (7) can be transferred in a controlled manner to the first port (9 A) on the first elastomeric channel (1A) upstream (11) of the microfluidic chip (7) and the second fluid (2B) can be transferred in a controlled manner to the second port (9B) on the second elastomeric channel (IB) upstream (11) of the microfluidic chip (7) (Figure 3B). In this embodiment, the first fluid (1A) and the second fluid (IB) can be the same or they can be different fluids. Although a rigid support (6) is not present in this embodiment, the relatively thick wall (12) located opposite the cam (4) enable to compress the elastomeric channels (1 A, IB).

In another embodiment of the invention based on the principle shown in Figure 2, the first liquid (2A) and the second liquid (2B) inside the microfluidic chip (7) described in Figure 3 can flow over the first elastomeric channel (1A) in the form of a hose connected to the first port (9 A) and the second port (9B) and the second elastomeric channel (IB) also in the form of a hose (Figure 4). In this case, it is possible to cut off the flow of the first fluid (2A) or the second fluid (2B) by compressing the first elastomeric channel (1 A) or the second elastomeric channel (IB) in connection with the rotation angle (a) of the cam (4) located between the first elastomeric channel (1A) and the second elastomeric channel (IB). In this embodiment, rigid supports (6) are required to be positioned across the cam (4) between the elastomeric channels (1A, IB).

A servo motor (13) is used to position the shaft (5) that is coupled to the cam (4) at the desired rotation angle (a) in the embodiments illustrated in Figures 3 and 4 (Figure 5). Servo motors are used in systems that require, positioning precision. Also, servo motors have been designed to take the desired position and maintain its position, unless a new command is received. Therefore, uncontrolled opening of an elastomeric channel (1) that is compressed during operation, is prevented by using a servo motor in the invention.

A cam-controlled valve produced in accordance with the embodiment described in Figure 4 and Figure 5 has been illustrated in Figure 6. The cam (4), the shaft (5) to which the cam is attached, the servo motor (13), elastomeric channels (1A, IB) produced from silicon having a 1.5 mm inner diameter and rigid supports (6) have been illustrated in Figure 6.

The cam control valve shown in Figure 6, has been tested in order to determine leakage rates at different flow rates. Accordingly, it is observed that the cam controlled valve shown in Figure 6 has a leakage rate below 6% between 1 and 100 mΐ/min (Figure 7). It is possible to maintain the leakage rate at the desired level by controlling the rotation angle (a) parameter. Accordingly the cam control valve can be used both to cut odd the fluid flow and to reduce the fluid flow.

In embodiments described between Figures 2 and 6, a cam (4) is used to control the flow in two elastomeric channels (1A, IB). However, by adding a second cam (4B) to the first cam (4A) located on the shaft (5), it may also be possible to control the flows within the third and fourth elastomeric channels (1C, ID) (Figure 8). Similarly, by increasing the number of cams (4) on the shaft (5), the number of flows that are controlled can be further increased.

Another way to increase the number of flows that are controlled is to change the profile of the cam (4) to enable the cam (4) to control three elastomeric channels (1A, IB, 1C) (Figure 9). Accordingly, at the first rotation angle (al) the cam (4) can compress the first elastomeric channel (1A) (Figure 9A), at the second rotation angle (a2) the cam (4) can compress the second elastomeric channel (IB) (Figure 9B) and at the third rotation angle (a3) the cam (4) can compress the third elastomeric channel (1C) (Figure 9C). Similarly, by changing the profile of the cam (4), it is possible to control even more elastomeric channels (1) with a single cam (4).

Using the combination of methods described in Figures 8 and 9, the number of elastomeric channels (1) that can be controlled, can be increased as desired.