Sensing and Detection

CAPPA has a wide variety of capabilities in sensing and detection applications. These include but are not limited to fibre-based sensing, trace gas sensing, sensors for machine vision and inspection and sensors for biomedical applications

Fibre-Based Sensing

Optical Fibres help in applications where the area of detection is small, or the location of detection is remote. Optical fibres can be used to stream light into a non-fibre optical detector (extrinsic), or optical fibres by itself can act as detectors (intrinsic).

Extrinsic detectors can be used to deliver and collect light in ‘hard-to-reach’ areas in various industries such as food and pharmaceuticals where extreme factors like temperature and pressure restrict the access. It can also be used in cases where other variables hinder the measurements, like in front of turbines or engines or transformers where electromagnetic fields make other measurement techniques impossible.

Intrinsic detectors are modified optical fibres that act itself as detectors. Modified fibres can measure strain, temperature, pressure and other quantities by analysing the variation in intensity, phase, polarisation, wavelength shift, or transmit time of light in the fibre. Fibre optic hydrophones, microphones, gyroscopes, hydrogen sensors etc. are already widely used in the industry.

Lab on fibre technology aims at a novel class of optical fibre sensors, which can achieve high levels of miniaturisation, which can be exploited in chemical and bio sensing. Lab on fibre transforms an optical fibre into a multifunctional sensor by integrating the components into micro and nanoscale.

Trace Gas Sensing

Conventional sensors cannot detect trace concentrations. Optical spectroscopy detection techniques employ cavities to enhance this detection limit further. Cavity Enhanced Ring-Down and Cavity Enhanced Absorption based methods are widely used for trace gas sensing in atmospheric, medical and industrial applications since they can accurately retrieve concentrations in parts per billion (ppb) to parts per trillion (ppt) range. These methods employ a high finesse optical cavity to achieve absorption path lengths of many kilometres in a compact instrument.
Quantum Cascade Lasers (QCL) based cavity enhanced spectroscopy can be used to study high-temperature chemical reactions of small organic and inorganic compounds in ambient air, breath samples for medical diagnostics, and industrial process gases.

Sensors for Machine Vision and Inspection

For long production lines, a repetitive inspection can be a laborious activity. Optical sensors that are cost-effective and accurate can replace these. These can be image sensors (vision sensors), which capture an image and compare the characteristics of the image to the reference image stored in its memory. For example, in drug production lines in pharmaceutical companies, optical image-based sensors can be used to distinguish damaged drugs. In addition, they can be used to check label alignment, assembly accuracy, component inspection, blister package verification, sorting, an inspection of moulds or packing inspections.

Motion sensors such as Passive Infra-Red (PIR) Sensors are widely used to send signals to a security systems control to alert and monitor a potential threat in a home or workplace. PIR sensors detect heat and movement while microwave sensors measure the reflected microwave pulses of a moving object. These sensors can be used independently or combined to form dual technology motion sensors. These technologies can be used to build a wireless grid and detect contact motion such that they trigger an alarm of the protected door/window is opened.

Cleaning based sensors can be used either for cleaning or for inspection of cleaned surfaces. Smart washrooms are already an established concept, which helps, in free and potentially unnecessary check on cleanliness. Digital toilets with sensors are expensive and would see their applications mostly in big public washrooms, which makes manual checking effortless and accurate. The data thus obtained can also be made to get historical data of events, optimising events, like emptying a trash can when it is full rather than regularly every day.

Measuring trace contaminants on surfaces using small handheld devices is another focus of CAPPA. These devices can be used in pharmaceuticals, biomedical, and food product manufacturing. Deep UV laser-induced fluorescence-based sensors have a ppb limit of detection for many chemical and biological materials on surfaces as well as on liquids. A highly regulated critical quality industrial process such as cleaning verification benefits using such detection techniques not only in avoiding cross-contamination but also in saving production downtime.

Sensors for Biomedical Applications

Biomedical sensor detectors, detect medically relevant parameters such as blood pressure, temperature, and analytes like blood glucose, haemoglobin and O2 levels. They play a significant role in making medical diagnostics and patient monitoring more accessible and approachable to both technical and non-technical staff.

Wearable body sensors for analysing cardiac health, sensors for measuring respiratory rate, body temperature and pulse oximetry integrated into fitness trackers, are growing traction due to their ease of use and portability.

Optical sensory probes can be used for early detection and diagnostics of terminal diseases. Nanobio-science can be combined with highly sensitive optical detection technologies to detect malignant tissues. Usual diagnosis of this would require the investment of a sum of money that is not affordable to the common person. The optical biosensors are more easily developed, low cost, rapid construction, small size, high performance, high sensitivity and selectivity, high signal to noise, flexible and portable versions of their lab counterparts. These sensors can detect based on colourimetry, fluorometry, luminometry, and can be built on fibre optic-based or surface Plasmon resonance platforms.