Communicating with light-emitting diodes

Light in the supermarkets of the future may not only illuminate in the literal sense, but also metaphorically. Stephen van ‘t Hof and Thijs Wenveen believe it is possible to use light-emitting diodes to send simple information all around the shop.

Together with four other bachelor students at the 3mE faculty, Stephen van ‘t Hof (21) and Thijs Wenveen (21) developed price tags that are controlled by a kind of Morse code emitted by LEDs. This summer they defended their Bachelor’s thesis.

“LEDs are becoming more and more mainstream and they’re becoming better and faster,” says Wenveen. “This prompted our supervisors to give us the assignment to develop a communication system using LEDs.”

By ‘fast’ Wenveen means to say that the lights switch on and off very quickly. When looking at LED light, you are actually looking at flickering light, but don’t notice it. The light’s frequency can be controlled quite simply with software.


The price tags which the students developed receive the encoded light on a small solar panel. This panel sends the information to a microcontroller that interprets the information – a new price for a bunch of bananas for instance – which subsequently appears on the screen. The system also uses the light as an energy source.


Some wholesale shops already use a smart system with electronic price tags that can be controlled wirelessly. These shops don’t need to send their employees around the shop anymore with little paper stickers to change the price, which is a laborious and thus costly task.

“The disadvantage of these systems however is that they have to change the batteries every few years,” says Van ‘t Hof. “With our system, that’s not necessary. And you don’t have to install transmitters all around the shop, either.”


The students haven’t yet figured out if their price tags are energy efficient enough when further miniaturized (they are now still quite big, or about the size of a candy bar). “One idea we had to spare energy is to use e-paper as screen material,” says Van ‘t Hof. “This material only uses energy when it needs to change the information it depicts.”


Despite the advantages of LED communication, the young engineers believe electronic price tags are the future, not their system, because technologies like Bluetooth and Wi-Fi are fairly advanced already and people have a lot of faith in them. But this hasn’t dissuaded the two students from participating in the UfD-Imtech Bachelor Grants competition, a competition organized by the University Fund Delft.

Paul Rullmann ziet het en noemt het ‘vervelend’. Hij wijst er op dat zalen eigenlijk alleen in de zomer zijn op te knappen, omdat er dan geen onderwijs is. “De voorbereiding en uitvoering staan daardoor onder hoge druk. Op een gegeven moment ben je afhankelijk van je aannemers.”

Volgens Rullmann moeten de vier schermen een gelijke belichting hebben, maar hebben de beamers onvoldoende lichtsterkte. “Er wordt geëxperimenteerd met een andere beamer.”

Over de problemen met de elektronische pen zegt beheerder van de zalenpool Etty van der Leij dat het ‘een ingewikkeld progamma’ is. “Het is niet plug and play. Je moet hiermee oefenen.” Rullmann vindt dat docenten ‘redelijk eenvoudig’ met materialen moeten kunnen werken. “Je moet geen technicus hoeven zijn.”

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