Biosensor developed for simple measurement of virus total mass and particle number

A joint research team, led by Professor Kazuhiro Takahashi in Department of Electrical and Electronic Information Engineering at Toyohashi University of Technology, together with the National Institute of Advanced Industrial Science and Technology, and Toyo University, has developed, using Micro Electro Mechanical Systems (MEMS), a multimodal biosensor that can simultaneously measure the total mass and number of particles of viruses adsorbed on monolayer graphene in which atoms stand by themselves on a substrate.

The technology for rapid and accurate detection of targeted viral particles from complex body fluid specimens such as saliva is extremely important in the early diagnosis of infectious diseases. Bio-microchip technology is being studied as a detection technique that can be used without the need for specialized knowledge. However, it is difficult to accurately quantify only the target substance because foreign substances in the specimen become noise if they are nonspecifically adsorbed on the chip.

The research team has developed a resonant sensor in which a graphene is crosslinked on microcavities. The sensor is vibrated by the heat generated by the current flowing through the freestanding graphene film. The total mass of material that is adsorbed on the film can be detected in the order of zeptogram by the change in vibration frequency. At the same time the number of particles adsorbed on the film can be measured by the change in vibration amplitude (or electrical resistance) (by using phonon scattering phenomenon of the 2D film caused by the adsorbed particles).

When this sensor was used in the experiment to detect the novel coronavirus, even in the presence of high concentrations of protein contaminants, it was possible to distinguish its signal from those derived from the contaminants by analyzing the correlation between the mass and number of the particles. They succeeded in specifically detecting only the target virus.

In addition, by optimizing the process in molecular modification of the surface of the graphene film, the team succeeded in capturing virus particles in the level of 100,000 copies in 1 mL and achieved the performance that enables the measurement of the mass of even a single virus, the experimental detection limit of mass (23 attograms).

Because this sensor is driven by an electrical signal, it is easy to make the device smaller and less costly. This may be used for virus detection at medical institutions, homes, etc.

The research team aims to further expand the range of applications of this sensor and establish a technology to detect viruses not only in liquid samples such as saliva, but also directly in the aerosol floating in the air in real time.

Journal Information
Publication: Sensors and Actuators B: Chemical
Title: Multimodal detection of molecular mass and particle number using an electrothermally driven graphene resonant sensor
DOI: 10.1016/j.snb.2026.139924