Graphene concept art

Aerosol-printed graphene sensor detects allergens in tuna

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US researchers have developed a cheap and efficient graphene-based sensor which detects allergens and toxins in food. The sensors are created using aerosol-jet printing and adapted for this application, opening up the possibility of similar sensors for other applications.

The sensor is capable of detecting histamines (allergens) and toxins in food considerably faster than standard laboratory tests.

Graphene-based sensors created using chemical vapour deposition techniques – in which a gas in contact with a substrate on a reaction chamber slowly creates a thin film on the substrate surface – would be too expensive for this sort of application, while cheap and fast alternatives such as screen and inkjet printing do not offer sufficient control.

Instead, the researchers chose to use aerosol-jet printing to create high-resolution electrodes on flexible substrates, before adapting them into more specialised electrochemical sensors to detect histamines through a CO2 thermal annealing process.

“We developed an aerosol-jet printable graphene ink to enable efficient exploration of different device designs, which was critical to optimising the sensor response,” said Northwestern University’s Professor Mark Hersam, one of the senior authors of the 2D Materials paper.

Professor Carmen Gomes of Iowa State University, another senior author, commented: “Aerosol-jet printing was fundamental to the development of this sensor. Carbon nanomaterials like graphene have unique material properties such as high electrical conductivity, surface area and biocompatibility that can significantly improve the performance of electrochemical sensors.

“But, since in-field electrochemical sensors are typically disposable, they need materials that are amenable to low-cost, high-throughout and scalable manufacturing. Aerosol-jet printing gave us this.”

Pursuing this aerosol-jet printing allowed the researchers to experiment with changing the geometry through software control, opening up the option of rapid prototyping to optimise the design of the sensor.

The scientists tested their sensors in a buffering solution and tuna broth. They found that the sensor could detect histamine over toxicologically-relevant ranges, meaning that it could play a part in preventing adverse health effects (such as severe allergic reactions). The sensors also had a response time of 33 minutes, “a good deal faster” than equivalent lab tests.

Aerosol-jet printed sensors could be used in situations in which continuous on-site monitoring of food is necessary, such as food processing facilities, import and export ports, and some supermarkets.

The researchers also suggested that the sensors could be adapted for rapid monitoring of other targets like cells and protein biomarkers, opening up possible applications relating to the monitoring of fatal human diseases, animal diseases and food pathogens.

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