FELIX LENK AND HIS TEAM AT THE INSTITUTE OF NATURAL MATERIALS TECHNOLOGY IN TU DRESDEN ARE DEVELOPING A NEW WAY TO MONITOR PHYSICAL CONSTANTS.
Felix is part of a small research group formed by 6 PhDs at the Technical University in Dresden who are leading the concept of the “Smart Lab”. The idea for the lab of the future consists of three key areas: digitalisation, automation and miniaturisation. Within this field they are trying to establish different projects, such as lab automation or image processing of culture dishes. The, sens-o-spheres, their most exciting project, is currently driven by the idea of miniaturisation. The concept came about when Felix was doing his PhD. During some of his experiments he identified a key issue: sensor probes are very expensive and not practical.
He then found the solution: to create a low budget mini sensor. Since then, the idea has developed rapidly, and the results have been outstanding. “Often simulations show that a prototype will work in real life but in practice, they end up failing” Dr Lenk told us “In this case, the first simulations predicted that the volume where we could use the sens-o-spheres was limited but practical experiments proved that they actually work in a much bigger scale than we thought!”. Felix and his team have managed to enclose a micro-sensor, a microcontroller and a battery inside a transparent pea-sized plastic capsule.
THE SENS-O-SPHERE, A PEA-SIZED SENSOR, IS CAPABLE OF MEASURING TEMPERATURE AND SENDING WIRELESS SIGNALS TO A BASE.
Currently the sens-o-spheres can measure temperature but they predict they will soon be able to measure other variables such as pH, dissolved oxygen content or electrical conductivity.
The battery life of sens-o-spheres depends on the frequency of the signal being sent back to the base. If the sensor communicates every 5-10 seconds, then the battery would last for half a day, whereas if the message is sent once every 10 minutes, it could work for up to two weeks.
The sens-o-spheres are reusable and rechargeable. They can be sterilised in an autoclave and used up to 7 charging cycles. As the usage time is limited but the cost is very low compared to their market competitors, the idea is to put more than one sensor at a time. Sensor redundancy increases the reliability and validity of the sensor when measuring unstable variables such as pH, reducing errors to a minimum. One of the focus of their upcoming project is to enable localisation and positioning. Contrary to the way in which satellites and GPS work, which send electromagnetic signals through large distances, the sens-o-spheres work in a microlevel.
Some of the ideas they are exploring include configuration of the electric and magnetic field which can be measured and correlated to give an idea of the position. The biggest challenge for the team right now is to keep the low cost while increasing the efficiency of the process and making the usage time longer. As it takes about 1-2 hours to build the microcircuits, for the current prototype, Felix’s team is using components which are available and produced at a large scale. On the contrary to many of their projects which are normally only attractive for the scientific community, this project actually has loads of commercial applications and seems to be very attractive for a varied range of industries.
Many different fields are interested in using the sens-o-spheres, including the agricultural and pharmaceutical industries. The low cost of the sens-o-spheres not only allows more efficient and economic measurements but also means it can be used to gather measurements from different systems simultaneously. In fact, the sens-o-spheres are the only wireless micro-sensors which can process up to 24 different signals at the same time.“The first practical application for this prototype will be as a measuring system in the lab setting” Dr Lenk told us. “In fact, one of my PhDs is currently using one of these sensors on a scale of 100 ml up to 5L bioreactors.
In this case, the sensor moves around the bioreactor and measures the temperature of the liquid in the different sections. Most bioreactors tend to present irregular temperatures throughout, so the sensor can feedback more accurate results which will help develop a more efficient design”. In the future, the team is hoping the sens-o-sphere to evolve towards being used in environmental science, particularly in water treatment plants. Technically it will also be possible to use them in humans in the future, given the right approvals are obtained. “A possible use could be to feed it to patients and obtain a live temperature profile for over 2 days”, said Lenk. Space exploration could also be a future application for sens-o-spheres. Due to the reduced weight and volume of the sensors, it would be much less costly to send them to space than the current probes are. On the side of his research on sens-o-shperes, Felix has created the Technikum, an open source lab for the students at TU Dresden. At the Technikum, students from the university are able to develop their projects and transfer research ideas into practical applications. One of the most exciting projects developed at the Technikum is the “PetriJet” or “PJ31x”. The PJ31x is designed for image processing of samples and sorting of samples and is currently being used to analyse legionella samples in water.