07-09-2021 | By Sam Brown

Researchers from Korea have recently developed a new FET that can detect molecules with a high degree of sensitivity and work with concentrated solid solutions. What challenges does molecular detection face, what did the researchers developed, and how could it be used for future detection of viruses and other molecules?

Challenges of molecular detection

Electronic sensors can be found for substances and chemicals, including gas, methane, alcohol, CO2, and ozone. Detecting these compounds generally relies on a material whose electrical characteristic changes in the presence of the said compound. For example, volatile compounds readily react with tin-oxide filaments, which can control the gate of a transistor for amplification.

But trying to detect complex structures such as DNA, proteins, and organisms cannot be done using a basic sensing element. Instead, such circumstances rely on various tests, including Polymerase Chain Reaction (PCR), mass spectrometer, and spectrophotometer. While these can provide very accurate results, they are extremely large, cumbersome, and expensive. Trying to integrate any of these devices into a wearable device or robotic system is challenging and impractical.

Some FETs have been recently developed to try and detect structures such as the COVID-19 virus. Still, these FETs generally suffer from challenges, including the inability to work with solutions that are not dilute enough. Furthermore, the detection range of molecules in high concentrations is typically in the range of 1nm, which is generally smaller than the molecule being detected.

Researchers develop a practical Lipid-FET

Recently, researchers from Korea have developed a new FET device that utilises a cell membrane. The idea to use a cell membrane comes from the ability of living cells to control the flow of ions and prevent a high concentration of ions outside the cell to enter inside. The researchers focused on cells ability to do this and transfer this mechanism into the gate of a FET.

The resulting device, called a Lipid-FET, can detect target molecules and detect them in concentrated solutions. This new transistor design can also work with solutions such as blood without the need for dilution, meaning that it could function as an active molecular scanner in the bloodstream. Furthermore, the research team determined that their Lipid-FET is currently the world’s highest-performing device to date and could lead to a new range of molecular sensing devices.

What could a Lipid-FET device do?

The most obvious application for a Lipid-FET is its ability to detect molecules in the bloodstream. Sensory devices could be implanted into a patient who is then scanned for proteins known to cause medical issues, including cancer and Alzheimer’s. However, instead of being implanted into suspected patients, it could be implanted into anyone for long-term preventative measures (i.e. detect conditions before they become problematic).

Another application for such devices is to detect viruses in real-time using cheap sensors. The COVID-19 pandemic has demonstrated that controlling viruses poses a significant challenge as they are only practically detectable in those with symptoms. Instead, electronic sensors similar to smoke alarms could be fitted that would constantly check the air for the presence of viruses. Using a Lipid-FET that only reacts to the proteins found on the virus would ensure selectivity, reducing the number of false alarms produced.

By Sam Brown