In a new study, researchers demonstrate the capability of DNA biosensor components for a unique modular DNA biosensor. The researchers plan to integrate their design within a device the size and shape of a smartphone for low-cost clinical diagnostics. Credit: N. Hanacek/NIST
DNA biomarkers can be used to screen for a variety of genetic risk factors and diseases, such as cancer. Typical genetic screening methods are complex and expensive, while simpler methods using small biosensors have seen limited use due to low sensitivity or lack of reusability. In order to achieve high resolution, these single-use biosensors are typically integrated directly into field-effect transistors (FET), which means the entire device, including expensive circuitry, must be discarded after each use. Researchers at the National Institute of Standards and Technology (NIST), Brown University and CEA-Leti have developed a new modular DNA biosensor that allows FET devices to be reused while reducing unwanted signal noise associated with modular designs.
The sensors are inexpensive to produce, with single-stranded DNA probes placed on the surface that bind with the target biomarker, producing a voltage shift measured by the FET. Typically, when a sensor is placed further from the transistor, such as in a modular design, there is greater noise due to longer travel of signals through the device. For this reason, FET-based sensors are typically attached directly to the transistor to limit noise. The researchers overcome this challenge by using a specially designed low-power FET developed at CEA-LETI, which amplifies signals and compensates for the loss of sensitivity associated with wireless devices such as smartwatches. The double gate fully-depleted silicon on insulator (SOI) transistor reduced noise by more than an order of magnitude compared with single-gate transistors, allowing the sensor to remain separate and removable from the measuring device without sacrificing sensitivity.
The team tested the performance of their device by testing liquid samples that contained varying concentrations of DNA markers for ionizing radiation exposure. They found that the binding kinetics of the modular system were sensitive enough to accurately measure the DNA even at low concentrations, matching the performance of integrated FET-based sensors. As the sensors can be removed and disposed of, allowing the circuitry to be reused, this design could enable easier and more cost-effective DNA biomarker screening. The sensors can be easily mass-produced and can be used with an FET device about the size of a smartphone, opening up the potential for point-of-care applications. This research was presented at the 2022 International Electron Devices Meeting.
“If the reader is reusable, we can build more sophisticated technology into it and get higher precision out of the readings, and it can interface with the inexpensive and disposable sensing element,” said NIST researcher and co-author Arvind Balijepalli.
The researchers plan to further test the device by analyzing more DNA biomarkers caused by mutations. Additionally, the sensor could potentially be used to detect genetic material associated with viruses, such as SARS-CoV-2.