Nanotechnologies and Sensing and Instrumentation

Key Drivers

• Need for sensors and detectors
• Need for increased sensitivity, functionality and specificity
• Energy efficiency
• Ability to operate in harsh environments
• Need for smaller, lighter and inexpensive sensors

Some promising materials that can be manipulated to use as nanosensors include carbon nanotubes, nanofibres, nanowires, quantum dots and nanoparticles.

Application Areas
The increased surface area in nanosensors makes them ideal for a large number of applications in pervasive and cross sectoral areas including environmental, medical/healthcare, biotechnology, defence and security, health and safety, industrial, food and agriculture, oil and gas, process control, transport and many more.

Healthcare
Nanosensors for use in healthcare are either in the development stage or in the prototyping stage. Nanosensors can be used in the rapid diagnostics, pathogen detection, DNA sensing, clinical evaluation, real time cell imaging and drug screening. Perhaps one of the most important areas, which will significantly benefit is point-of-care diagnostics (Lab-on-chip). Applications include:

• Nanowire sensors which can be used for virus detection
• Cancer diagnostics
• Nanotubes for use in asthma breath analysers
• Cadmium selenide quantum dots for use as sensors to uncover tumours within the body by exploiting its fluorescence properties.

Security and Defence
The high sensitivity of nanosensors can be utilised in detecting biological and chemical threats like anthrax, plague, small pox etc. They can also be used for detecting explosives and carbon nanotubes can be used to detect toxic gas agents like sarin. Additionally nanosensors are used for detecting real time soldier health monitoring.

Environmental Monitoring, Health and Safety
Nanosensors can be used in pollution monitoring, trace gas detection in atmosphere and for the detection of toxins, bacteria and other contaminants in food and water. Rapid food testing kits and drinking water monitoring systems using nanosensors are currently being developed. Nanomaterials have also been used to produce packaging materials which act as a sensor changing colours when the food becomes inedible. Carbon nanotubes functionalised with peptides have been shown to detect trace amounts (parts in trillion) of nickel, copper and lead in water.

Oil and Gas
Nanosensors for gas detection can be used in detecting toxic gases from mines and wells. There is also an increased interest in using nanosensors for detecting the precise location of oil reserves. Increasingly oil and gas are found in porous rocks and in sandstones. Specific focus is on understanding the chemical/physical properties of reservoirs, 3D distribution of reservoirs and the paths of fluids. Nanosensors due to their small size are expected to be able to enter the pores and send the relevant data. Magnetic nanoparticles are also being studied as an above surface detection mechanism to find oil reserves.

Automotive
Nanosensors can be used for the accurate measurement of pressure, temperature, engine knock, acceleration and gas emission. They are also being considered for possible use in electronic stability control and crash sensing. The current application focuses mainly on engine and exhaust management and have also been used to measure the cabin air quality in aircrafts and cars. In the future, with the increased use of hydrogen fuel cells in cars, nanosensors might be used to check for leaks, purity of the formed hydrogen and for the measurement of contaminant gases (C0, H2S).

Agriculture
Nanosensors can be used in precision farming through real time crop monitoring and delivering targeted actions. The sensors made of carbon nanotubes and nano-cantilevers are small enough to trap and measure individual proteins or even small molecules. Fertiliser and pesticide delivery systems which can respond to environmental changes and deliver the cargo in a controlled manner in response to changes in magnetic fields, heat, ultrasound, moisture etc. are currently being developed.

Industrial process control
Ammonia is replacing CFCs as a more environmentally acceptable refrigerant. Current low cost sensors cannot survive the extreme temperature environment. Nanosensors can be used as a refrigerant detector. They can also be used in closed bioreactors (pharmaceuticals) and open bioreactors (landfills) for multivariate gas detection.

Some UK companies to highlight

• Oxford Nanopore Technologies: Genetically engineered proteins self assembled to form stable Nanopores which can be used to detect a wide range of molecules, metal ions, reactive compounds, Proteins and DNA
• Oxonica: Silica-coated, surface enhanced Raman scattering (SERS)-active metal nanoparticles for highly-multiplexed immunodiagnostics, molecular diagnostics, and proteomics
• Endomagnetics: Magnetic nanoparticles combined with a detector for Breast Cancer detection
• Applied Nanodetectors: Carbon nanotubes for Asthma detection
• Cascade Technologies: Quantum Cascade Lasers for trace gas detection
• Stratophase: Bio-chemical sensors providing real-time detection and analysis of bio-molecular and chemical interactions. High precision measurements of refractive index for process control.
• Peratech: Quantum tunnelling composites for sensitive textiles

Conclusion
Nanotechnology based sensing platforms offer high sensitivity compared to existing platforms. It enables simultaneous multivariable detections and will miniaturise the sensors to unprecedented levels. There are many companies claiming to offer nanosensors around the world. However, only few of them have products utilising nanolevel properties. Integrated micro/nano systems provide improved sensitivity, resolution and overall performance. They will also allow simultaneous detection and data processing, however, integrating these nanoscale sensors and packaging remains a significant challenge. The economic advantage lies in improving or enhancing the capability of existing sensors to break the industrial conservatism and to compete with the mature technologies.