CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under the Paris Convention to European Patent Application No. 19216228.7 filed on Dec. 13, 2019.

The present disclosure belongs to the field of microfluidic devices. More precisely, the present disclosure refers to a microfluidic device configured to deliver a controlled amount of a liquid to an analysis tool.

BACKGROUND OF THE DISCLOSURE

The development of precision medicine calls for major progress in the development of new tools and methods adapted for detection and analysis of biomolecular materials.

The field of microfluidics offers key advantages for that purpose: microfluidic chips provide control and manipulation of tiny amounts of liquids in sub-millimeter channels and other structures leading to the reduction of the amount of liquid required for low cost analysis, and provide automation capabilities for reliable analysis.

Given the benefits of reduced sample volume, highly predictable liquid dynamics, high resolution and sensitivity, and dimension scalability, microfluidic chips are used in numerous applications.

EP1150105 discloses a microdosing device configured to control a small amount of liquid of the order of microliters or sub-microliters. The quantity of liquid injected into a buffer tank or ejected from a buffer tank can be determined by measuring the pressure in the buffer tank.

The disclosed microdosing device is not adapted for use in combination with analysis tools such as a microfluidic chip, for example, which would be necessary for detection and analysis of biomolecular materials. Furthermore, filling or purging of the buffer tank of the microdosing device with a liquid is complicated.

Accordingly, a need exists for a compact microfluidic device that alleviates the above-mentioned problems.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a microfluidic device configured to deliver a controlled amount of a liquid to an analysis tool, wherein the microfluidic device comprises:a buffer tank configured to contain a liquid and/or a gas;at least one level sensor configured to measure a liquid level in the buffer tank;a pneumatic system configured to create selectively a positive or a negative pressure in the buffer tank;at least one intake port to let a liquid in the buffer tank;at least one delivery port to inject a controlled amount of liquid from the buffer tank onto the analysis tool;at least one drain port with a controlled drain valve, located on the lower part of the buffer tank to discharge the liquid from the buffer tank;a first check valve located upstream of the intake port and a second check valve between the buffer tank and the analysis tool.

This microfluidic device allows to precisely control an amount of liquid, such as a biomolecular material, and to analyze the liquid on the analysis tool.

The pneumatic system controls the injection of liquid into the buffer tank and the injection from the buffer tank onto the analysis tool, wherein the amount of liquid in the buffer tank is controlled by the level sensor.

The use of the first check valve ensures that liquid does not flow back out of the buffer tank through the intake port. The use of the second check valve ensures that liquid does not flow from the analysis tool back into the buffer tank.

In one embodiment, the analysis tool is a microfluidic chip.

A microfluidic chip comprises a set of micro-channels etched or molded into a material and integrates at least one “laboratory” analysis function, such as chemical analysis. It allows for precise analysis of a biomolecular material.

In one embodiment, the analysis tool comprises at least one test strip.

A test strip is a band/piece/strip of any material used for fast and low-cost analysis of a biomolecular material.

In one embodiment, the pneumatic system comprises at least one pump.

The at least one pump allows controlling and/or regulating the pressure in the buffer tank.

In one embodiment, the pneumatic system comprises two pumps.

One pump is configured to generate a positive pressure in the buffer tank and the other pump is configured to create a negative pressure in the buffer tank.

In one embodiment, the pneumatic system comprises a single pump and four valves.

A positive/negative pressure can be generated in the buffer tank in dependence on which of the valves are open/closed.

In one embodiment, the at least one pump is an air pump.

For creating a positive pressure the at least one pump injects air into the buffer tank.

For creating a negative pressure the at least one pump evacuates air from the buffer tank.

Using an air pump is advantageous since an air pump is significantly cheaper than a liquid pump.

In one embodiment, the inner walls of the buffer tank are hydrophobic.

The use of hydrophobic inner walls minimizes adhesion of the liquid to the inner walls and hence minimizes the risk of contamination between two subsequent analyses, thus improving the reliability and accuracy of each analysis.

In one embodiment, the buffer tank has a diameter which increases from the lower part of the buffer tank to the upper part of the buffer tank.

This particular shape reduces the risk of liquid being trapped at the lower part of the buffer tank, thus avoiding contamination between two subsequent analyses and improving the reliability and accuracy of each analysis.

In one embodiment, the buffer tank has a volume in a range from 0.1 mL to 10 mL.

This allows storing a sufficient amount of liquid necessary for analysis on the analysis tool. It further allows for precise control of the amount of liquid injected onto the analysis tool.

In one embodiment, the intake port is configured to supply a liquid to the buffer tank from a funnel which is located upstream of the first check valve.

The funnel facilitates injection of a liquid into the buffer tank through the intake port.

In one embodiment, the level sensor configured to measure the liquid level comprises at least two electrical contacts at the inner side of the buffer tank.

An establishment of an electrical conduction between at least two electrical contacts indicates the liquid level and hence the amount of liquid in the buffer tank.

In one embodiment, the microfluidic device comprises a pressure sensor configured to measure a pressure prevailing in the buffer tank.

Precise pressure measurements allow controlling and determining the amount of liquid injected into the buffer tank and from the buffer tank onto the analysis tool.

In one embodiment, the buffer tank comprises a calibrated leak.

The calibrated leak allows for a controlled leakage which avoids an overpressure inside the buffer tank.

The calibrated leak also allows establishing the optimum pressure range for the pneumatic system aiming at optimizing its performance, in particular when a pump is used. This is a cost effective solution allowing the use of a low-cost pump, although the system exhibits a high accuracy.

In one embodiment, the buffer tank comprises a pneumatic port.

This enables a high precision of regulation of the pressure in the buffer tank.

In one embodiment, the microfluidic device comprises a control unit configured to acquire data from the pressure sensor and from the level sensor, and configured to control at least the pneumatic system and the drain valve.

The control unit controls the operation of the microfluidic device.

Another aspect of the disclosure comprises a method to analyze a controlled amount of liquid on an analysis tool, wherein the method comprises:generating, by a pneumatic system, a negative pressure in a buffer tank thereby letting in a liquid into the buffer tank through a first check valve,generating, by the pneumatic system, a positive pressure in the buffer tank thereby injecting a controlled amount of liquid from the buffer tank onto the analysis tool, through a second check valve,analyzing the controlled amount of liquid on the analysis tool and processing the obtained data;controlling a drain valve to discharge a remaining liquid from the buffer tank after injection of the liquid onto the analysis tool.

This method allows operation of the microfluidic device.

In one embodiment, a pressure in the buffer tank is measured repeatedly by a pressure sensor, and the negative and/or positive pressures are controlled as a function of the data provided by the pressure sensor.

This feedback loop ensures accurate operation and precise control of the amount of liquid injected into and discharged from the buffer tank.

In one embodiment, a liquid level in the buffer tank is measured repeatedly by a level sensor, and the phase of generating a negative pressure in the buffer tank is stopped according to a predetermined level condition.

When stopping the phase of generating a negative pressure in the buffer tank, the injection of liquid into the buffer tank ceases.

In one embodiment, the pneumatic system comprises a single pump and four valves, wherein the phase of generating a negative pressure is obtained by running the pump and controlling first and second valves at closed state and controlling third and fourth valves at open state, wherein the phase of generating a positive pressure is obtained by running the pump and controlling third and fourth valves at closed state and controlling first and second valves at open state.

This allows creating a precisely controlled positive/negative pressure in the buffer tank on demand.

