Graphene Sensors

A team of Spain-based researchers has developed a highly sensitive detector for identifying molecules via their infrared vibrational “fingerprint”. The new detector converts incident infrared light into ultra-confined "nanolight" in the form of phonon polaritons within the detector´s active area. This mechanism serves two crucial purposes: it improves the detector's overall sensitivity and enhances the vibrational fingerprint of nanometer-thin molecular layer placed on top of the detector, allowing this molecular fingerprint to be more easily detected and analyzed. 

The compact design and room-temperature operation of the device hold promise for developing ultra-compact platforms for molecular and gas sensing applications.

Zentek has announced that its wholly-owned subsidiary Triera Biosciences has received a CAD$1.1 million (around USD$791,000) Government of Canada contract to test its multivalent aptamer technology for the rapid drug discovery of therapeutics or prophylactics of highly pathogenic avian influenza (“HPAI”) A(H5N1).

Triera was awarded a these funds through Innovation, Science and Economic Development Canada's (“ISED”) Innovative Solutions Canada (“ISC”) program: Health Advanced And Emerging Medical Technologies. Triera’s multivalent aptamer technology was selected for its potential to be used as a rapid drug development platform.

Researchers from the Korea Advanced Institute of Science and Technology (KAIST), Korea Institute of Machinery & Materials and Seoul National University of Science and Technology (SEOULTECH) have shown that laser-induced graphene (LIG), patterned with femtosecond laser pulses, can serve as a versatile material for temperature/strain sensing, stray light absorption, and heat management for smart spacesuits and telescopes. 

Direct laser writing of laser-induced graphene (LIG). Image from: Advanced Functional Materials 

The team has developed a manufacturing technique that addresses the challenges posed by the harsh conditions that space equipment must function in. The scientists' new process uses precisely controlled laser pulses to transform a Kevlar's surface into a porous graphene structure, effectively converting ordinary Kevlar fabric into a multifunctional material. 

Researchers at the University of Virginia, Ajou University and Soongsil University have developed an AI-powered system that mimics the human sense of smell to detect and track toxic gases in real time. Using advanced artificial neural networks combined with a network of sensors, the system quickly identifies the source of harmful gases like nitrogen dioxide (NO₂) that poses severe respiratory health risks.

Schematic of biological and artificial olfactory receptor. Biological receptors interact with odor molecules through specific binding, whereas artificial receptors use catalytic dissociation by Pd nano-islands for selective gas molecule adsorption on graphene surfaces. Image credit: Science Advances

The artificial olfactory receptor features nano-islands of metal-based catalysts that cover a graphene surface on the heterostructure of an AlGaN/GaN two-dimensional electron gas (2DEG) channel. Catalytically dissociated NO₂ molecules bind to graphene, thereby modulating the conductivity of the 2DEG channel and allowing the system to detect gas leaks with extreme sensitivity.

Polaritons are coupled excitations of electromagnetic waves with either charged particles or vibrations in the atomic lattice of a given material. One of their most attractive properties is the capacity to confine light at the nanoscale, which is even more extreme in two-dimensional (2D) materials. 2D polaritons have been investigated by optical measurements using an external photodetector. However, their effective spectrally resolved electrical detection via far-field excitation remains unexplored. This hinders their exploitation in crucial applications such as sensing, hyperspectral imaging, and optical spectrometry, banking on their potential for integration with silicon technologies. 

Recently, researchers from Spain's ICFO, the University of Ioannina, Universidade do Minho, the International Iberian Nanotechnology Laboratory, Kansas State University, the National Institute for Materials Science (Tsukba, Japan), POLIMA (University of Southern Denmark) and URCI (Institute of Materials Science and Computing, have reported on the electrical spectroscopy of polaritonic nanoresonators based on a high-quality 2D-material heterostructure, which serves at the same time as the photodetector and the polaritonic platform. Subsequently, the team electrically detected these mid-infrared resonators by near-field coupling to a graphene pn-junction. The nanoresonators simultaneously exhibited extreme lateral confinement and high-quality factors. 

While graphene aerogels have advantageous properties like extremely low weight, high porosity and good electrical conductivity, engineers who tried to use them to develop pressure sensors have encountered some difficulties. 

Image credit: Nano Letters 2024

Specifically, many of these materials have an intrinsically stiff microstructure, which poses limits on their strain sensing capabilities. Researchers from Xi'an Jiaotong University, Northumbria University, UCLA, University of Alberta and other institutes recently introduced a new fabrication strategy for synthesizing aerogel metamaterials to overcome this limitation. This strategy fabricates a durable graphene oxide-based aerogel metamaterial that exhibits a remarkable sensitivity to human touch and motion.

Researchers from Korea, including ones from Seoul National University and Korea Research Institute of Standards and Science, have developed a room-temperature self-activated graphene gas sensor functionalized by nickel oxide (NiO) nanoparticles and demonstrated its application to wearable devices monitoring ammonia gas.

The team introduced NiO nanoparticles onto graphene micropatterns to create a highly selective and sensitive ammonia sensor that can operate effectively even in the demanding conditions of wearable electronics. This advancement represents a potential step forward in sensor technology, particularly for applications such as food quality monitoring and wearable devices that track air quality.

Researchers from the University of Cambridge, University College London, Imperial College London, Kumoh National Institute of Technology (KIT) and Beihang University have developed a wearable ‘smart’ choker for speech recognition, that has the potential to redefine the field of silent speech interface (SSI) thanks to embedded ultrasensitive textile strain sensor technology.

Where verbal communication is hindered, such as in locations with lots of background noise or where an individual has an existing speech impairment, SSI systems are a cutting-edge solution, enabling verbal communication without vocalization. As such, it is a type of electronic lip-reading using human-computer interaction. In their recent research, the scientists applied an overlying structured graphene layer to an integrated textile strain sensor for robust speech recognition performance, even in noisy environments.

Archer Materials has started experiments to detect and monitor chronic kidney disease on its Biochip graphene field effect transistor (“gFET”) sensors.

Archer, through one of its foundry partners, has reportedly verified a process that directly grows graphene surfaces to produce enhanced devices, rather than transferring the graphene to a device from a wafer, as previously done. The team has tested the devices by storing them in normal air conditions over a two-month period, finding no significant degradation in performance. 

Researchers from Tufts University recently developed a graphene-enhanced highly sensitive saliva-based cortisol sensor – eliminating the need for invasive blood tests.

The Point-of-Care (POC) electrochemical biosensor boasts a detection limit of 0.24 fg/mL, making it 100 times more sensitive than existing saliva tests. This innovation relies on the Gii-Sens “electrode” – a sensing strip produced by nanomaterial company, iGii – integrated into the sensor.