Joint development of scientists at the Technion and IBM laboratories in Switzerland: a device that separates biological particles according to their size using an electric field. The device may be used in rapid diagnosis of corona patients * due to the fact that the virus is relatively large – about 100 nm in diameter
A joint study by researchers from the Technion and IBM Laboratories in Zurich led to the development of a new method for separating particles and molecules from small samples. The device may assist in the rapid analysis of samples from Corona patients, under a grant from the Innovation Authority.
In an article published by the researchers in the journal Angewandte Chemie, they present a new method for separating particles and biological molecules from a liquid. This development has been described by one of the reviewers as “a huge contribution to the field and a breakthrough that only occurs once every decade or two.”
It is a tiny device that quickly separates different types of particles: small particles stay near the opening of the device while large particles move away from the opening quickly. The group calls the new method BFF, short for bidirectional flow filter (bidirectional flow filter). The article presents a theoretical analysis of the system, validation of its experiments and guidelines for the design of future devices for different uses. The research group at the Technion was led by Prof. Moran Berkovich from the Faculties of Mechanical Engineering and Biomedical Engineering, head of the Laboratory for Microsurve Technologies.
The device presented by the researchers in the article is a microfluidic chip in which the liquid sample is separated into its components by flowing through virtual channels through electro-osmosis – control of fluid flow by electric fields and surface charge. In the present study, the researchers used this technology to create a two-way flow – the flow of the liquid in two opposite directions simultaneously. The traditional approach – flow control using pumps, valves and ducts – does not allow such flow patterns to be achieved.
A video explaining the study
In the new device, when particles are injected into the flow field they behave in a well-explained but surprising way: small particles remain in place while large particles are transported rapidly. According to doctoral student Vanessa Becheva from the Technion, one of the two main authors of the article, “Particles in liquid and gas move randomly – a phenomenon called brownish motion. This movement leads to the fact that particles in the gas tend to disperse in space so that they will eventually be evenly dispersed in it. This is the mechanism by which we can smell, after a while, a bottle of perfume that opens on the other side of the room – because the molecules move randomly and disperse in space in a process also called diffusion. “
Diffusion processes are characterized by a correlation between the size of the particle and its level of diffusivity – small particles are more diffuse than large particles. In the innovative device developed by Prof. Berkowitz’s research group, bi-directional flow takes place, and the result is that the large particles in the sample, characterized by low diffusivity, are swept away by the current, while the small particles run rapidly between opposite current lines. The flow. The result is a tiny device that separates particles according to their size.
“The principle here is quite simple,” says Dr. Federico Pertura, a postdoctoral fellow working at IBM Labs in Zurich, who is also a lead author in the article. “Surprisingly this is something that has not been done so far, probably due to technological limitations. We have been able to overcome these limitations through ongoing research that has included many attempts and improvements, and the result is a solid device that can be commercially manufactured for the benefit of new diagnostic tools and as a basis for new research tools of tiny samples. ”
Prof. Moran Berkowitz explains that “Most biological diagnostic devices are based on generating a response between sensing molecules (probes to the molecules or target particles that are sought, followed by removal of the target molecules that are not bound to the target. This process, especially in the last stage, is very complicated to implement. “In small samples. Our method does this quickly and efficiently, as long as the sensing and target molecules are different enough from each other.”
The team is now working on adapting the method for rapid monitoring of the SARS-CoV-2 virus based on a sample from a throat swab. Dr. Govind Gaikla of IBM explains that “Fortunately, viruses are relatively large – about 100 nm in diameter, much larger than antibodies or other sensory molecules used by us. Our idea is to put the sample in our flow cell, where the viruses will meet glowing sensing molecules that will attach to them, and only the marked viruses will flow out while the excess sensing molecules are left behind. ”
The research was funded by the European Commission for Research (ERC) MetamorphChip and the BRIDGE program funded by the Swiss Innovation Authority (Innosuisse) and the Swiss Science Foundation (SNF).