It is on the verge of mass-producing these labels, which can be printed onto plastic film and stuck onto containers - from bottle to boxes - to take temperature readings and reduce the unnecessary dumping of perishable foods and medicines.
Ten years ago, the two physicists turned their book learning to the practicalities and R&D of nanotechnology and then started the Nanosciences Innovation Centre at the University of Cape Town. Before too long, they were talking of a future where self-powered, printed temperature sensors would be pasted onto bottles, vials and containers to monitor perishable goods. They spoke of the unwarranted waste of foods and medicines, how these precious cargoes were often stored or transported under poorly controlled conditions, and then had to be dumped wholesale when prescribed to do so by best-before dates for want of better measures.
Now it seems that the future they foretold is here. Bearing a resemblance to a conventional printed circuit board, the 'temperature-tracking label" is designed to monitor perishable goods.
Stick it onto a box with dairy products or medicines inside and the sensor system, about the size and shape of a credit card but thinner and more flexible, takes a reading of the temperature of that box, giving retailers a more educated sense of shelf life and product safety.
However, what sets the Sensor Label apart from that old circuit board is cutting-edge technology. Every component - the sensor, the battery, memory and transistor logic - is printed, using run-of-the-mill printing processes. The working electronics is found in the electronic inks, harnessing materials that can conduct a variety of signals.
The Cape Town company's one-of-a-kind sensor is printed with environment-friendly and non-toxic water or natural oil-based inks containing silicon nanoparticles that form the necessary electronic material. The nanoparticles are superfine grains - each particle less than a hundred nanometres - of the commonplace mineral known as silicon. (Silicon, the most widely used semiconductor material, is said to be the eighth most-common element in the universe by mass.)
The temperature-sensing label is a turning point for the company. Through the Thinfilm label, it is playing a game-changing part in a temperature-monitoring market that is predicted to reach over US $3.2 billion by 2020.
"It shows what is possible with printed electronics technology," says Britton. "It's a major step and very important from a commercial point of view."
The label "demonstrates a complete closed system built from printed and organic electronics," explains Thinfilm of the technology.
"It is the sensor that is 'at the heart' of the Thinfilm label," adds Härting. The sensor, which includes a thermistor, a kind of resistor widely used in temperature sensors, picks up the ambient temperature, passes that information on via the transistor logic (whose job it is to receive and disseminate information) to a printed memory (which stores the data that can be retrieved for at least 10 years later), which in turn puts a reading onto a display screen.
Thinfilm has options for sourcing every other part in its label, except its sensor say Britton and Härting. "It is the only printed temperature sensor available," points out Härting.
It certainly has encouraged Thinfilm to announce a go-live date for the Smart Sensor Label. They plan to go into production by the end of 2014, printing the sensors using roll-to-roll processes, ie on rolls of flexible plastic. It may also give Thinfilm the edge over competitors in the market.
"PST thermistors have been used in our printed integrated temperature sensor systems, which have established a new paradigm for printed electronics," says Thinfilm' Thomas Strubreiter. "Using a PST sensor allows the company to reach a cost target necessary for mass adoption, in competition with both colour-changing labels and disposable temperature threshold sensors based on conventional silicon-based electronics."
Moreover, if the Thinfilm product is an example of what Britton calls a "high-volume, low-value" enterprise, the founders of PST Sensors have their eye on some "low-volume, high-value" projects as well. That includes supplying temperature sensors for a NASA project targeting the production of 'printable spacecraft'. There technicians and engineers imagine - and are looking to develop - what they call 'atmospheric confetti', electronics printed much like the Thinfilm label on thin plastic sheets. These sheets can be dropped over a distant planet - like Mars - to record heat and light measurements that can be communicated back to engineers on Earth.
There are all manner of other applications. As part of the World Design Capital 2014, with partners Sharon B Design and Head-on Design, the company will be showcasing the development of its Kushushu Mat (kushushu means 'it's hot' in isiXhosa). This mat, crammed with sensors, can take the temperature of a person lying on it and could be used in the monitoring and medical care of babies, hospital patients and the elderly. There is also a Kushushu heater, requiring no power cords, in the works.
On top of that, it is in talks with customers on other medical diagnostics. Other applications will be on display at the upcoming Printed Electronics USA conference and exhibition in Silicon Valley from 20-21 November.
PST may well have revolutionised the design of transistors along the way. At the IDTechex 2013 Printed Electronics Conference and Exhibition in Berlin, Germany, in April this year, the company announced that it had developed a 'current-switching transistor', said to be the first new kind of transistor in 65 years. While existing transistors only control an electric current between two of the transistor's three terminals - the emitter and collector - its transistor can also incorporate the third terminal (the base) by switching the direction of the current from between the base and the collector, to between the emitter and the base.
"That opens up many possibilities for developments in transistor logic, power management and printed display technology," said Raghu Das, CEO of printed electronics research company IDTechEx, at the time.
The new transistor, once incorporated into PST temperature sensors, could also do the job of the transistor logic on the Thinfilm label.
"It is no longer just a temperature sensor," says Härting, "it's already a system." Its label heralds a "ubiquitous intelligence" that will turn the "Internet of Things into the Internet of Everything," claimed Thinfilm CEO, Davor Sutija, on announcing its Smart Sensor Label.
The two founders also think that printed electronics will change the world, as we know it. "It's doing what the microchip did by putting intelligence into items. Printed electronics can put intelligence into everything," concludes Britton.
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