Scientists are developing microflow control technology for blood testing devices

A research group in Japan has developed a microfluidic control technology that can be applied to small blood testing devices and, as a result, has developed a novel integrated immunoassay device. This microfluidic control technology is expected to address cost issues – one of the limitations to societal adoption of microfluidic chips – and enable a convenient blood testing device.

One team is supervised by Assistant Professor Shunya Okamoto from the Department of Mechanical Engineering at Toyohashi University of Technology, and the other by Associate Professor Yoshiaki Ukita from the Graduate Division of Interdisciplinary Studies at the Faculty of Engineering at Yamanashi University.

The results of this study were published in RSC Progress April 26.

Compared to conventional analytical systems, those using microfluidic chips offer advantages such as minimized sample volume and reduced analysis time. However, technology is required that precisely controls fluids in extremely small spaces of approximately 50–300 μm.

Enzyme-linked immunosorbent assay (ELISA) is an analytical technique used in blood analysis to measure cancer biomarkers; however, although highly sensitive, ELISA requires complex fluid control.

Conventional testing used complex designs and operations, such as placing multiple valve structures and combining pumps, to perform such fluid control, thereby increasing the cost of test devices and chips; in addition, extensive user training is required to operate such devices. These issues have become major limitations in the community implementation of ELISA.

To solve these problems, researchers developed a centrifugal microfluidic chip with autonomous control functions. The chip consists of a microfluidic chip with only a simple channel structure that can be formed using mass production technologies such as injection molding. The team also performed analysis by simply rotating the chip at a constant rotational speed for several dozen minutes (constant rotation).

So far, they have demonstrated that this autonomously controlled centrifugal microfluidic chip can perform ELISA, which requires complex fluid control. However, the main limitations are that a large number of samples are required for analysis and users require multiple chips and extensive dispensing operations to quantify the test substance.

To overcome these limitations, researchers developed a dispensing mechanism that can automatically distribute reagents instead of manual work, and demonstrated the performance of a “multi-sample micro-volume simultaneous analysis device” that uses a dispensing mechanism in the analytical unit.

Demonstration analysis performed using IgG antibodies as test substances showed that although the sample volume was sufficiently small – approximately 5 µl (mm³), which can be collected even by pricking your finger – and has the same detection sensitivity (63.4 pg/ml) as the previous manual analysis, the analysis time can be reduced by a third to approximately 30 minutes.

The research results used prototype devices that can be built at the laboratory level. However, in the future, the team will explore practical applications by optimizing the design using mass processing methods and materials.

This fluid control technology enables control to be realized using microfluidic chips with a simple structure. In addition, the centrifugal control device is also simple to operate because fluid control is possible at a constant rotational speed. Therefore, this technology may help to solve cost problems – one of the limitations of the social implementation of microfluidic chips.

Currently, blood analyzers are only installed in central laboratories of general hospitals. However, with advances in cost reduction and device miniaturization, as well as better functionality, blood analyzers can be installed in clinics, drugstores and households, thereby increasing the availability of blood tests and improving people’s quality of life.