IVD technology丨Advantages and disadvantages of centrifugal microfluidics

Industry news | 05 December, 2022 | CACLP

Centrifugal microfluidics belongs to a branch of microfluidics, which refers to the control of microfluidics by centrifugal force to drive liquid flow. It integrates the basic operations involved in biology and chemistry on a small disc-shaped chip, so it is also called Lab-on-a-Disc (LOAD).

The application of centrifugal microfluidic technology in the field of in vitro diagnosis becoming more and more mature. In the field of biochemistry, centrifugal biochemical disks based on centrifugal microfluidic technology dominate POCT biochemical analysis. In China, companies with centrifugal biochemical disk products include Tianjin MNCHIP Technologies, Chengdu Seamaty Technology, Shaoxing Pushkang, Suzhou Hicomp, Shenzhen Genrui Biotech Inc and so on. In the field of immunodiagnostics, we are also seeing more and more immune multi-test products based on centrifugal microfluidics. Typical representatives in China are Chengdu VACURE Biotechnology, Shijiazhuang Hipro Biotechnology, Shaoxing Pushikang (centrifugal microfluidic chemiluminescence) and so on. In the field of nucleic acid detection, nucleic acid detection products based on centrifugal microfluidics include Focus Diagnotics (in cooperation with 3M), GenePOC (acquired by Median), Capitalbio Biotechnology, Shanghai Speed Core Biotechnology, Shenzhen Edan Instruments and so on.

Let us talk about the advantages and disadvantages of centrifugal microfluidics.

Advantage 1: The drive mode and the interface between the instrument are simple

Centrifugal microfluidics mainly rely on centrifugation to drive the flow of liquids. In the design of the instrument, only a centrifugal motor can be realized, which makes the instrument simple and compact. In addition, this simplicity is reflected in the interface between the instrument and the consumables.

Advantage 2: No residue in liquid drive

In centrifugal microfluidics, under the high-speed rotation of the disc microfluidic chip, the liquid is less likely to remain in the pipeline and chamber. In other drive methods, it is difficult to ensure that there is no liquid residue in the pipe. In microfluidic chips, the absence of residue in the liquid drive is an important guarantee for the consistency of detection。

Advantage 3: Simple parallel processing

On a dish microfluidic chip, the ubiquitous centrifuge field radiating outward from the center of the circle makes it easy to realize the parallel processing of reaction reagents. Under the action of a centrifugal field, the liquid can sequentially fill multiple reaction chambers arranged in a circumferential or spiral tube. The benefits of this parallel processing are not only the detection of single-sample multi-index based on multiple reaction chambers, but also the non-contact signal reading of multiple reaction chambers.

Advantage 4: Simple separation based on density difference

Due to the centrifugal field, it is particularly simple to achieve density difference-based separation on centrifugal microfluidic chips. In vitro diagnostics based on blood samples, the first step in testing is often to isolate plasma from whole blood. In centrifugal microfluidics, this operation is very simple. With simple centrifugation, blood will be two layers, plasma and blood cells, due to the density difference between blood cells and plasma. Through a special design, the upper serum can be automatically separated in the centrifugal microfluidic chip for the reaction of the downstream timing of the centrifuge disk.

Advantage 5: Consumables have good manufacturability and low cost

Compared with other microfluidic products, centrifugal microfluidic chips generally consist of two components: a main chip and a base plate. The main body of the centrifugal microfluidic chip is integrated injection molding, and the final state of the product can be formed by only sealing the bottom plate, which can ensure the yield of the entire microfluidic consumables mass manufacturing from the perspective of the product side, and at the same time, it also greatly reduces the mass production cost of microfluidic consumables.

Disadvantage 1: High design threshold

Unlike the microfluidic technology that many traditional products rely on, centrifugal microfluidics is its own in the discipline system and has a certain depth. In centrifugal microfluidics, there are three fundamental forces, which are centrifugal force, Coriolis force, and Euler force. Making full use of these three forces can effectively control the liquid. centrifugal force radially facing outward; The Coriolis force, or Coriolis force for short, is a description of the offset of a particle in a rotational system due to inertia relative to the linear motion produced by the rotating system. The Coriolis force comes from the inertia of the motion of the object and is dependent on the rotational speed; The Euler force is proportional to the angular acceleration of rotation and exists only when the rotational acceleration is not zero.

In centrifugal microfluidics, the valve design is also very particular. For example, the design essence of centrifugal biochemical disks - siphon valves, people without experience in centrifugal microfluidics cannot think of such a sophisticated design.

Disadvantage 2: The centrifugal field is strongly coupled between the steps, and the flexibility is weak

On centrifugal microfluidic chips, the ubiquitous centrifugal field is both a good thing and a bad thing. The good thing is that it's very easy for us to implement parallel reactions in multiple reaction chambers, and the bad thing is that the ubiquitous centrifuge field leads to strong coupling between the different reaction steps. For example, a test has five reaction steps, and when we realize the automatic operation of these five steps on a centrifugal microfluidic chip, if a step is not stable enough, then we are likely to readjust the speed and steering corresponding to that step, and even the rotational acceleration.

If you want to solve the problem of this step by adjusting the centrifugal field, you often have to consider the impact of the change of the centrifuge field on other steps of the whole process.

Disadvantage 3: For PCR, temperature control is difficult

For biochemical detection and immunodiagnosis, and even nucleic acid detection based on constant temperature amplification, temperature control based on air bath can be easily stabilized in centrifugal microfluidic systems. However, for centrifugal microfluidic systems that use QPCR technology to achieve nucleic acid detection, the barriers to temperature control are very high.

From these dimensions, in the centrifugal biochemical disk, the temperature control system is simple, and because the design is basically borrowed from Abaxis, the design threshold is not a problem. Coupled with the advantages of superimposed centrifugal microfluidics itself, the driving method is simple, easy to integrate the separation of plasma in whole blood, can achieve multi-index detection of multiple reaction chambers, and microfluidic consumables have good manufacturability, so it has finally formed a situation in the field of biochemical POCT, centrifugal biochemical disks occupy a dominant position.

Filed under：

microfluidics

Press contact