The device’s magnetostrictive clad plate is composed of iron, cobalt and nickel, generating power via alternative magnetisation caused by vibration. The vibration resonance frequency of the Fe-Co/Ni plates, which were coated with the receptor protein coronaviruses, changes when the virus is absorbed, alluding to Covid-19 particles being in the air.
“We know that resonance frequency changes when the weight of a magnetostrictive material changes, but we set out to answer whether this is also the case when a virus is absorbed and if this absorption is detectable," said Fumio Narita, co-author of the study and professor at Tohoku University's Graduate School of Environmental Studies.
To answer these questions, Narita and his team first had to create an efficient inverse magnetostrictive sensing system that could operate without batteries and communicate information wirelessly.
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According to the team, they modified a 0.2mm thick Fe-Co/Ni plate with a rectifier/storage circuit that harvested bending vibration energy and enabled the wireless transmission of information. The plate transmitted signals with the power obtained from bending vibration at 115Hz or 116Hz. A change in clad plate weight affected the resonance frequency and altered the transmission intervals, meaning it could detect any substances that adhered to the clad plate.
Next, the group created the bio recognition layer, choosing to focus on human coronavirus 229E (HCoV-229E) – one of the seven types of coronavirus that affects humans.
They immersed the clad plate in a CD13 protein solution and performed sensing experiments. When the coated clad plate was subjected to bending vibration, the resonance frequency decreased after HCoV-229 was absorbed, verifying whether the charged power could transmit virus detection as a signal.
“We were able to confirm that the magnetostrictive composite material can detect the virus and transmit this detection data using power generated by itself," added Narita. "The self-sustaining nature of the device renders it possible to link it to IoT technologies in the future, something not capable with current biosensors."
The device could be used on other pathogens with modifications to the bio recognition layer, the team said. In future, Narita added that the team hopes to develop the device and see if it applies to viruses such as MERS, SARS and Covid-19.
Further details of the study were published in the journal Sensors and Actuators A: Physical.
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