ThinKing April 2022: Quantum sensors – The future belongs to the minis



In the past, quantum sensors – which are used, for instance, to conduct MRIs in the medical field – were large, heavy, and unwieldy. But what if you could shrink these sensors down to the size of a one euro coin? The Institute of Smart Sensors (IIS) at the University of Stuttgart is now doing just that.

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Researchers led by Dr. Jens Anders are developing a quantum sensor that is 1,000 lighter and smaller than others on the market with the help of 3D printed structures, which will be suitable for use in applications like non-destructive materials testing to optimise lightweight technology structures.

The Baden-Württemberg State Agency for Lightweight Technology will present the ThinKing for this innovation in April of 2022. Every month, Leichtbau BW GmbH promotes innovative lightweight technology products and services in Baden-Württemberg under this label.

At a glance:

  • Lighter: 16 g instead of around 16 kg – a weight reduction by a factor of 1,000 represents a quantum leap for quantum sensors.
  • Short production times: These small quantum sensors can be manufactured in half an hour, on average.
  • Inexpensive: A lightweight quantum sensor costs just a few euros, including the materials.
  • New possibilities: The magnetic resonance sensors with electronics miniaturised via chip integration can be used to develop wearable, spintronics devices that can be used in many different areas. 

Lightweight technology is revolutionising magnetic resonance measurement technology: Smaller magnets and structures produced through additive manufacturing are helping to miniaturise the sensors, which were previously large and unwieldy.

“We are using 3D printing as one way to create lightweight, yet highly precise magnets for quantum sensors” explains Dr. Jens Anders, Head of the Institute of Smart Sensors (IIS) at the University of Stuttgart, which is receiving the ThinKing for April 2022 thanks to its development work.

Wide range of applications

The magnets can be used in magnetic resonance sensors for nuclear magnetic resonance (NMR) and electron spin resonance (ESR or EPR) to analyse the chemical structures of molecules or the chemical compositions of mixtures. Because they are many times smaller and lighter than previous designs, the sensors make truly portable systems for point-of-use and point-of-care measurements possible for the first time. Therefore, their applications are almost endless: from medical technology to destruction-free materials testing in lightweight construction, to quality controlling in manufacturing fibre composite materials like carbon-fibre reinforced plastics and glass-fibre reinforced plastics, as well as in inline process controlling for radical polymerisation. They can be used to test organic fluids (like blood and urine), soft and liquid foods (like milk or butter), polymers, biological tissues, and porous materials.

Lightweight, inexpensive, and quick to manufacture

Magnetic resonance sensors consist of a coil as the sensor, excitation and diagnostics electronics, as well as the magnets and iron components that create a homogeneous magnetic field. The iron components are known as yoke and pole pieces, whereby the latter often also contain specialised structures (shim structures) to improve the homogeneity of the magnetic field.  Miniaturisation has not changed this basic structure.

In the past, the applications of magnetic resonance sensors were limited greatly by their size and weight. Past sensors were at best mobile, but certainly never wearable. Manufacturing traditional magnetic resonance magnets is complex, and may take multiple days.

At the Institute of Smart Sensors, the research team headed by Dr. Jens Anders is using commercially available plastic filaments with ferro-magnetic particles that harmonise with the extremely small magnets in the sensor structure to manufacture the previously heavy yoke structures.  The 3D-printed structures, made of a lightweight plastic filament containing iron, are an inexpensive way to quickly manufacture powerful, wearable magnets for spin-based quantum sensors.

Additive manufacturing allows the poles of the magnets to be shaped as needed, improving homogeneity over current state of the art technologies. In addition, the structure can be printed on the in-house 3D printer in just a few minutes using an FDM process (fused deposition modelling). The prototype shows that commercial ferro-magnetic filaments can be used for key components of magnetic resonance magnets.

As a result, the weight of the sensor can be reduced to just 16 grams, at a size of just a few cubic centimetres. The quantum sensors are, accordingly, inexpensive as well: Costs are around two euros per magnet, with a production time of just 30 minutes. 

“The high level of homogeneity, alongside the low weight and associated portability of our magnets are truly unique selling principles” says Dr. Anders. “Currently, we are planning a spin-off company which will combine the printed magnets with our chip-integrated sensors, to bring wearable, spin-based analytic devices to the market”.

Lightweight technology uses material more efficiently thanks to lighter quantum sensors

Miniaturising the sensors opens up additional potential for lightweight technology thanks to potential applications in material manufacturing: destruction-free material testing in situ, as well as the option for inline process controls during manufacturing, will make it possible to quantify the quality of fibre-reinforced plastics. This will facilitate better product design without the significant safety margins that were necessary in the past. In the future, the new, lightweight magnets and chip-integrated spin quantum sensors could make it possible to save materials, and indirectly reduce CO2 emissions.

About the Institute of Smart Sensors (IIS) at the University of Stuttgart 

The IIS researches miniaturised and scalable sensor systems, focusing on spin-based quantum sensors. The institute currently has around 30 employees.