Cardea Graphene Biosensors to Receive New ‘Electronic Nose’

Article By : Liam Critchley

Cardea has recently been awarded a $1.1 million grant to develop an "electronic nose" using its graphene BPU unit for diagnosing infectious diseases in people's breath.

Graphene sensors have been at the forefront of graphene electronic commercialization efforts, and more graphene sensors have come on to the market than any other graphene–enhanced electronic device. Among graphene sensors, biosensors have the largest market share. Cardea is one company that has released graphene–enhanced biosensors in the past using its biosignal processing unit (BPU) for detecting cancer.

Now, Cardea is expanding its graphene biosensor offerings and has recently been awarded a $1.1 million grant by the Bill & Melinda Gates Foundation to develop an “electronic nose” using the graphene BPU unit for diagnosing infectious diseases in people’s breath.

It started with cancer detection

Cardea’s entry into the graphene biosensor space started by offering an alternative biopsy pathway for detecting cancers. Traditional biopsies are tissue biopsies, but they are very invasive and do not often offer any form of early–warning detection. Over the years, liquid biopsies have become more commonplace because they are less invasive and can detect cancer from bodily fluids. Cardea built on this trend and used a graphene transistor platform within the BPU to enhance the biopsy detection process.

These graphene–enhanced cancer sensors use next–generation sequencing to offer a way of detecting different cancers. Most cancers can be detected using different biopsy methods, but Cardea used the graphene platform to detect for multiple cancers in a single fluidic sample ― offering a way of detecting cancer early if the source of the cancer is unknown.

The BPU platform can analyze different biosignals from multiple communication channels within the body, in an approach known as multiomics (the study of the different “omics”). So the platform can analyze nucleic acid biosignals (genomics) and amino acid biosignals (proteomics), as well as metabolomics, transcriptomics, and complex intercellular communication biosignals. All of these are analyzed in real time within the same sample and show the versatility that graphene can bring to biosensing (and sensing in general).

The BPU graphene platform from Cardea

The BPU platform is used in the original cancer–detection devices and is set to be used in the electronic nose that will be developed soon. The BPU is essential for both the cancer diagnostic platform and the recently announced electronic nose, and is being developed as a central unit that can be adapted for different applications and clinical scenarios.

Cardea’s BPU platform consisting of a capture molecule, BPU, gateway reader and computing, and gateway analyzer. (Source: Cardea)

The BPU platform consists of a number of key components and is essentially a microprocessor that converts a biological signal into an electrical signal. Similar to any detection device, the BPU possesses computing hardware in which a sensing reader and an analyzer are housed to convert any output from the sensing surface into a detectable and usable output for the user. In terms of the actual sensing part of the platform, there are two key components: the graphene layer and the capture molecules.

The graphene layer, which is utilized as a field–effect transistor (gFET), is used to directly translate different biological signals into digital information. Graphene is widely used as a sensing platform in different industries because it has a high active surface area where functional sensing groups can be attached, but it also has a high electrical conductivity and charge carrier mobility. This makes graphene sensitive to any localized changes, as the binding of any biomolecules (or any stimulus for that matter) changes the conductivity across the graphene sheet.

Sitting on top of the graphene layer are different capture molecules. The gFET coupled with a biosensing group results in a graphene sensing platform that is semiconducting in nature. So when a biomolecule binds to the surface, it changes the electrical properties of the graphene and generates a detectable signal that can be harnessed into a readable output. Many different capture molecules (for binding with certain biomarkers) can be placed on top of the gFET layer, so it is possible to detect RNA, DNA, and protein–based biomolecules on a single platform. This is why the system is adaptable for both cancer diagnosis and disease detection.

The small size of graphene (both in terms of its thinness and lateral dimensions) means that a number of gFETs can be placed next to each other on a single chip, expanding the range and biosignal bandwidth of the sensor. It is primarily this small–scale nature, alongside the sensing effectiveness of graphene, that allows for a versatile and sensitive detection platform.

Utilizing the BPU platform as an electronic nose

Cardea’s electronic nose development has only just been announced but builds on the success that the cancer–detection platform has had. The aim is to utilize the same graphene BPU platform in the company’s electronic nose, much like it has in its cancer diagnostic devices. As detailed above, the ability to create small and customizable gFETs means that the process for customizing the platform toward infectious diseases should be relatively straightforward, provided that it is easy to attach the relevant capture molecules on top of the graphene layer.

The BPU technology has already shown that it can be produced at scale, as Cardea already has the capacity for manufacturing thousands of units. The target market is for detecting infectious diseases in developing countries, because compared with other diagnostic platforms, the ability to detect a range of infectious diseases helps to bring the development time and the cost down, making it more appealing to markets that cannot afford to spend as much money on medical devices. And it opens the doors to communities that have traditionally been underserved when it comes to medical testing.

As mentioned above, the utilization of graphene in the detection mechanism helps to increase the sensitivity of the platform, so much so that it has been showcased that these new BPU–based platforms can detect if someone has an infectious disease by their breath. The aim of the funded project is to verify the ability of the BPU functionalized with an insect odorant receptor to detect agonist odorants (agonist odorants are a substance that initiates a response with a receptor).

The electronic nose being developed has the potential to detect a range of diseases, including Covid and malaria, and can also be used to detect different cancers like its predecessor. It is thought that the platforms based around odorant sensing could be used in a wide range of applications, from clinical health settings to environmental monitoring, agriculture, and biosecurity applications. The versatility of the BPU could mean that the platforms may be used even wider in the future once this project has finished and is being used in the real world.

This article was originally published on EE Times.

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