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Sensor Research

CLARITY

Monitoring our lakes and rivers - the intensity of light depends on the phosphate concentration in the sample.

Monitoring our lakes and rivers - the intensity of light depends on the phosphate concentration in the sample.

Centre for Sensor Web Technologies is a unique, multi-disciplinary research centre which has a mission to “Bring Information to Life”. This refers to the harvesting and harnessing of large volumes of sensed information so that it can be accessed by the right person at the right time. The Adaptive Sensors Group (ASG) is the sensor element of CLARITY. The ASG is located in the National Centre for Sensor Research (NCSR), at Dublin City University (DCU). Here a team of scientists and engineers, led by Prof. Dermot Diamond, work to develop new sensing materials and build sensor networks to monitor the world around us. Here are some examples of projects that the group is involved with.

Sensors to Monitor the Environment

The complete phosphate analysis system consisting of sampling, pumping, microfluidic manifold.

The complete phosphate analysis system consisting of sampling, pumping, microfluidic manifold.

Water is essential for life and water pollution can threaten the survival of life. In cities contamination can occur from outflows from sewage treatment, while in rural areas much of the pollution originates from animal wastes and commercial fertilizers. Phosphate contamination can lead to algal blooms which deplete the dissolved oxygen in our lakes and rivers causing aquatic life to die. The Adaptive Sensors Group has developed a complete analysis system to measure phosphate levels in water systems. Phosphate can be detected using a colorimetric technique called the molybdenum yellow method. This involves mixing an aqueous sample with a reagent which results in a yellow solution. The intensity of the yellow colour depends on the amount of phosphate present. A portable analysis system uses optical detectors and microfluidic devices to measure the phosphate concentration. The results are sent regularly to the laboratory by an electronic control board which has a modem for wireless communication.

Air quality is another area of great importance for our well-being. Chemical sensors may be used to detect hazardous gases. One project that the Adaptive Sensors Group is working on is to automatically monitor the emission of gases from landfill sites. There are 79 licensed landfill sites in Ireland, 29 of these being active. Methane and carbon dioxide are two of the main gases that are emitted. 

Landfill gas monitoring unit to measure methane and carbon dioxide.

Landfill gas monitoring unit to measure methane and carbon dioxide.

Furthermore, methane is a flammable gas under the correct conditions of temperature, pressure and oxygen presence. Therefore, monitoring methane build-up is important for those working on or near landfill sites. Current methods to monitor landfills are labour intensive and time consuming therefore an autonomic system where multiple sensors can be deployed throughout a site is needed. As with the water monitoring system the collected data is returned to a user via wireless communication with a GSM modem. In addition, other chemical sensors can be used for the measurement of toxic and odorant gas targets, including hydrogen sulfide, ammonia, carbon monoxide, sulphur dioxide and nitrogen dioxide. The monitoring platform has already been tested to measure carbon monoxide concentrations in a multi-storey car park.

Wearable Sensors to Monitor our Health

Sensor glove for stroke rehabilitation - flexible stretch sensors are coated onto the fingers and the thumb.

Sensor glove for stroke rehabilitation - flexible stretch sensors are coated onto the fingers and the thumb.

Wearable sensors may be used to provide valuable information about a person’s physiology. This has many applications in healthcare including managing chronic illness, preventative healthcare and rehabilitation. There are also many applications in the sports sector to tailor training programmes, improve performance and assess the athlete’s health. The advantage of using wearable sensors is that they allow continuous monitoring of the wearer in an innocuous manner. Sensors integrated into everyday clothing mean that the wearer is monitored in a natural setting – for patients this means they can be at home and be remotely monitored by doctors and for athletes this means that their physiology can be assessed on the track, pitch or court. However, for wearable sensors to become truly ubiquitous, textile-based sensors need to be integrated into the fabrics of the clothes we wear. New advances in textile technology are making this possible.

Microfluidic chip to measure sweat pH

Microfluidic chip to measure sweat pH

A number of "smart" garments are being developed by the ASG at Dublin City University to assess the health of the wearer. Electronic textiles make use of conductive fabrics and metallic threads. Textile yarns can be knitted and embroidered into fabric to create electodes and form interconnections between sensors. Aside from metallic materials there are a class of polymers which have inherent conducting properties. Fibres can be spun using these conducting polymers and they can also be coated onto the surface of different textiles. Coating foam with a conducting polymer such as polypyrrole creates a sensor with piezoresistive properties – this means that when the foam is compressed the conductivity changes, thereby creating a textile pressure sensor. Similarly a knit fabric can be coated in the same way resulting in a textile stretch sensor. The fabric itself becomes the sensor and can therefore be easily integrated into our clothes. At the Adaptive Sensors group these types of sensors have been used to detect body movements such as ribcage movements during breathing and joint movements e.g. a sensor glove to measure hand movement. Pressure sensors have been integrated into shoes and insoles to monitor the pressure and contact time of the foot on the ground. Such sensors for monitoring movement are useful for improving athletic performance and also for rehabilitation to help patients perform their exercises correctly.

Other fabric sensors can be made using dyes which change colour depending on temperature, UV light or pH. The colour change of these fabrics can be seen by the human eye or by using optical detection components such as LEDs and photodiodes. Dyeing a fabric with a pH sensitive dye creates a fabric pH sensor which exhibits a reversible pH change. Wearing such a fabric in contact with the skin can be used to measure the pH of sweat. This is useful for investigating fluid and hydration needs during sport. The group has developed a wearable microfluidic device to sample and measure sweat pH during exercise.

Carbon dioxide sensor is integrated into the boot of a firefigher's uniform

Carbon dioxide sensor is integrated into the boot of a firefigher's uniform

Wearable sensors can not only monitor the wearer’s body but also their surrounding environment. The Adaptive Sensors Group is involved with an EU funded project called ProeTEX (Protection e-Textiles) that aims to develop smart wearable sensors for emergency disaster intervention personnel such as firefighters to improve their safety, coordination and efficiency. Carbon dioxide and carbon monoxide sensors are being integrated into firefighter’s clothing to acts as a personal warning system to avoid oxygen deprivation.

Linking the Physical and Digital World

The aim of CLARITY is to take the sensed data from the physical world in which we live and link it with the digital world of modern communications & computing. This will create new ways to monitor personal health and fitness and offers the potential for self-regulating and adaptive environmental monitoring systems. The CLARITY CSET is a partnership between University College Dublin and Dublin City University, supported by research at the Tyndall National Institute (TNI) Cork. This work is funded by Science Foundation Ireland under 07/CE/I1147.

For more information visit:

www.clarity-centre.org

www.dcu.ie

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