Development of innovative liquid and high-resolution short-range sensors

Laura Reich Diez

Startup Stories

Ilmsens GmbH was founded in 2016 out of the TU Ilmenau. The name "Ilmsens" reflects on the one hand the relation to Ilmenau and the TU Ilmenau, on the other hand it underlines the focus of Ilmsens: sensor technology. The team around Hans-Christian Fritsch, managing director of Ilmsens, develops the most modern ultra-wideband sensors according to the highest quality standards. Ilmsens' sensors are used in liquid analysis and short-range sensor technology (smart home, electronic fence, vital sign detection), where they offer great added value due to their miniaturizability, insensitivity to harsh measurement environments and real-time capability.

Fluid analysis based on impedance spectroscopy makes it possible to determine the composition of complex mixtures of substances and to detect any changes that occur. This not only allows statements to be made about the current state of the process fluid, but also about the development of predictive models for predictive maintenance. This allows problems in processes to be identified at an early stage and thus also to be responded to optimally.

The high-resolution close-range sensor technology from Ilmsens GmbH, in contrast, makes it possible to detect objects as well as the smallest movements. The determination of the distance to the sensor, the speed and the position is non-destructive and thus insensitive to external influences such as bad weather or dirt.

The five managing directors of Ilmsens
The five managing directors of Ilmsens

Ultra-wideband microwave sensor technology - an unwieldy term

"Let's break the term down into its individual parts and start from the back: Sensor technology is clear, these are sensors," explains Managing Director Hans-Christian Fritsch. "In this context, microwaves means that we work in a frequency range of a few gigahertz. That's where WLAN and mobile communications also transmit. Ultrawideband means that we don't just use a few frequencies. A good comparison is always a loophole in a wall. I can look through the wall and see what's behind it, but I still can't get a real impression of the world. Ultra-wideband is then the panorama window. Here I can observe a lot and pick up clear information about the world. In addition, we are developing our own semiconductor chips - that is unique for startups," says Fritsch. "We have developed the ultra-wideband technology in two directions. First, liquid analysis (impedance spectroscopy) and second, high-resolution short-range sensing. For liquids, we provide information about compositions, contamination, quality information and processes. The short-range sensor technology is a sensitive system, which can penetrate material within certain limits and detect the smallest movements there.

"Compared to optical systems, we do not need light. Darkness, fumes, walls, wood or plastic cladding are no hurdle for Ilmsens technology."

Impedance spectroscopy - what is it and how does it work?

Although liquids occur in a wide variety of industrial environments as raw materials, operating materials, intermediate or end products, Ilmsens impedance spectroscopy enables fast and non-contact measurements across all industries that provide information about the efficiency and quality of processes. This is particularly interesting when either sensitive process chains or very aggressive liquids are involved.

Impedance spectroscopy is a non-destructive, fast and inexpensive measurement method that can be used to measure electrical material parameters such as impedance, conductivity and permittivity. These parameters are frequency-dependent and vary depending on the frequency of the alternating electric fields with which they are measured.

Every material has an electrical resistance, which is in parts frequency-dependent and unique for this material. This value (and in addition also the permittivity) describes the "permeability" or resistance of a liquid for an electromagnetic wave. If the portion of the signal reflected at the liquid is considered, conclusions about the composition of the material can be drawn. The more frequencies a signal contains, the better it is possible to distinguish between materials.

"Simply stated, this is the background to the fluid analysis we are doing," Fritsch explains. "Every material has a resistance to electromagnetic waves, which is dependent on the frequency of that wave. Combining them over a wide range of frequencies gives a kind of fingerprint - a unique identifier for a substance within a mixture. With the help of appropriate mathematical models, one is then able to derive target parameters of liquids from the impedance spectrum, i.e., to determine the searched concentrations".

Ultra-wideband impedance spectroscopy thus provides insights into the materials under investigation that would otherwise not be apparent at first glance. This can be of interest to users who want information that goes beyond the performance of conventional sensors.

Since each application is unique, each process requires different methods of interaction with the media. "We discuss the possibilities with our partners, as each plant or product in which our sensors are to be installed does have its own specific requirements in terms of sensor dimensioning, installation location, form factor, robustness, etc.," Hans-Christian explains the implementation of Ilmsens technology.

Interviewee and Managing Director Hans-Christian Fritsch
Interviewee and Managing Director Hans-Christian Fritsch

Miniaturized, dynamic and mobile - the advantages of Ilmsens technology

"The system concept is significantly different from classic radar or metrology solutions," explains Hans-Christian. "This gives us the chance to record a lot of information by measuring very fast and miniaturized at the same time by means of the broadband sensors."

Ilmsens has developed a highly innovative technology that can replace the proven network analyzer (NWA) measurement method in many areas. Since the NWA measurement is performed on only one frequency, which is varied one after the other, the acquisition of a wide frequency band takes a lot of time. This requires no or only very slow changes in the characteristics of the measurement scenario, thus limiting the practical applications. The measurement method developed by Ilmsens operates in the time domain and can therefore measure thousands of frequencies simultaneously. This significantly shortens the measurement time and enables the investigation of changing objects or scenarios. Especially with radio measurements, for example, the measurement of moving persons or the recording of their vital signs becomes possible.

In addition, classic NWAs are bulky laboratory devices for stationary use and are usually large, heavy and consume a lot of energy. This makes NWAs particularly unsuitable for mobile use when measuring radio scenarios. "Our Ilmsens devices, on the other hand, are miniaturized due to the monolithic integration of high-frequency electronics and can be used in a wide variety of locations. In addition, they consume significantly less energy and are more robust against harsh measurement environments than a laboratory device.

Digital twin makes predictions about process development and provides recommendations for action

On the software side, the improved information content of the measurement data enables the creation of a "digital twin" for the process under investigation. This model is able to make predictions about the process development based on the measured values and provide recommendations for action. The measurement data from the sensors installed in different plants can be linked with each other and enable further helpful conclusions to be drawn about process optimization. The high measuring speed enables the measurement of inhomogeneous material samples or samples with high flow velocity, e.g. in bubble and flowmark/strip detection.

Universal hardware facilitates integration into existing technology

As mentioned, the sensor will be designed so that it can be easily integrated into existing processes. Depending on the type of evaluation - for example, monitoring, comparison, prediction or recommendation - there may be different requirements for the process technology. For example, when implementing the sensor into a process, care must be taken to ensure that the sensor is installed in a location that is representative of the objective of the measurement.

From the sensor to the measurement data

"If we use machine learning algorithms for data evaluation, it has to be learned by means of training measurements. Training data and corresponding reference data are required. Here, we work closely with our cooperation partners. How the measurement data or the calculated information is then presented to the user or processed further depends in turn on the respective area of application."

A high technology product - setbacks and difficulties

"Of course, we also had to deal with setbacks, anything else would simply be a lie," laughs Fritsch. "To give you an example: Corona hit us because, as described in the project, we work with partners and it happened that partners paused the projects with us. That was annoying for us. But all the paused projects have since been restarted, so I would really only call that a dip. What was a challenge for us with a really high-tech product that requires a lot of explanation, or still is today, is to first take partners, consultants or investors along with us and explain our technology to them so that they can evaluate it accordingly at the end.

"Our business model is designed around the fact that we are the experts for the data and the upstream electronics. Ilmsens technology is universally applicable in diverse domains, but we are usually not the experts for the use cases.

We look for the collaboration partners who have domain knowledge to develop our products for the market. 5-HT Digital Hub Chemistry & Health is an excellent partner for us and we are very excited to work together."

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