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Visual indicators


Rapid detection and visual indication

VTT has especially strong experience in the development of visual indicators sensitive to the presence of volatile substances and oxygen. Indicator concepts have been developed for non-volatile target analytes too. Also, various printed and embossed concepts for humidity indication have been proposed, and VTT has considerable experience with several concepts based on printed enzymes. Conductive polymers have also been harnessed for the detection of volatiles and particles.

For printed indicators, VTT's offering covers all phases in product development from application needs through feasibility testing to roll-to-roll manufacturing process development and concept characterisation services.

The competitiveness of VTT in the development of printed indicators and sensors is rooted in our multidisciplinary expertise and capability of handling several stages in the concept development process. 

  • Understanding of diagnostic needs in several application areas such as food, environment, processes, indoor air, and health
  • Development of detection chemistry based on know-how in chemistry and biochemistry
  • Formulation of the reaction chemistries in inks, and optimisation of ink compositions
  • Development and optimisation of printing methods on laboratory scale
  • Understanding and characterisation of ink–substrate interactions
  • Product concept development
  • Pilot-scale trials and manufacturing


Vast market opportunities for low-cost indicators and sensors

Several market sectors can be foreseen for low-cost indicators and sensors. Areas of application can be roughly divided between those related to everyday life of different consumer groups and those connected to natural and built environment. Beyond these, a vast application area is naturally found in medical diagnostics. 

Food quality indication – in particular, related to packaged foods – was the first example of the application of low-cost printed indicators. However, in addition to quality indications for consumer-use packaged food, several other applications have been identified. Among these are verification of authenticity and success in sealing or a gas flushing process. Consumer groups such as infants and elderly people require special attention. Indicators could be used as, for example, part of a food home-delivery system for the elderly, to ensure an unbroken temperature chain in the meal transportation and proper disposal of meals that have been stored too long and therefore are not safe for  consumption. In addition, indicators could offer an additional tool to verify water quality and food safety in developing countries. 

In well-being, cosmetics, sports, and health-related applications, the indicators could be used to facilitate correct timing and dosage of medicine or supplement uptake, help to verify the authenticity of a package and product, improve brand protection and indicate possible tampering/opening or deterioration of a product. Particularly in cosmetics, also tests for skin type and treatment efficiency could be foreseen as potential applications. Indicators could even be developed for disposable tests for urine and sweat, in monitoring of diet optimisation and sufficient nutrient intake. In the natural and built environment, several applications for disposable sensors can be identified in water quality analysis, industrial monitoring, agriculture and farming, security applications, and indoor air monitoring. For instance, in indoor air applications, indication of residuals from building materials or cleaning substances could be carried out via indicators and sensors for volatiles. Printed sensors based on conductive polymers could be used for the indication of particles and gases such as NH3. Indication of humidity and moisture as enabling factors for microbial growth are also of major importance in indoor applications.