Jump to content
Powered by

Fraunhofer PAMB accelerates the development of medical devices

Dr. Auguste van Poelgeest is head of the “Control Systems for Medical Engineering” research group that is part of the Project Group for Automation in Medicine and Biotechnology (PAMB). The project group is based at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA. In an interview with Dr. Ariane Pott from BIOPRO Baden-Württemberg, van Poelgeest explains the role of automation in the field of medicine and how hardware-in-the-loop techniques help to considerably reduce product development time.

Control systems are part of everyday life, yet only a few of us probably understand what they actually are. Can you explain in simple terms what control systems are and what they can be used for in medicine?

Dr. Auguste van Poelgeest is head of the “Control Systems for Medical Engineering” research group that is part of the Project Group for Automation in Medicine and Biotechnology (PAMB). The project group is based at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA. © Fraunhofer IPA

I'll take metering pumps as an example; they are pumps used, amongst other things, in chemotherapy as dosing devices to administer a defined drug quantity. They are also used in bioprocess plants to add certain substances to a system. All these procedures rely on parameters such as pressure and flow rate that are set, and need to be kept, at a defined value. If you want to measure pressure, you install a pressure sensor and compare the measured value with the preset value. If these values differ, you need to think about how the parameters can be varied in order to maintain the preset pressure value. This can be done by opening a valve, adjusting motor speed and so on. Control systems do all this automatically.

Compared to automation technologies used in other areas, there are greater quality and safety requirements for medical dosing devices. An oxygen pump in intensive care wards must be very finely tuned, to avoid too much increase in pressure. An oxygen pump is usually equipped with two sensors that monitor and adjust the pressure. If only one sensor is used, it has to have a very low failure rate.

Of course, there are similar requirements for pumps used in other industrial sectors. In the chemical industry, the consequences of a mistake can also be very serious. The PAMB project group therefore adheres to valid quality standards and also provides the necessary documents for certification, if required.

The Fraunhofer project group PAMB offers companies a medical device testing service using the so-called hardware-in-the-loop method. How does this work?

Hardware-in-the-loop simulations can be carried out here. © Fraunhofer IPA

Hardware-in-the-loop (HiL) is a technique that has traditionally been used in the automotive industry. For example, when a new model of car is being developed, the team of engineers seeks to work in parallel, designing all the hardware, control units, electronics and the software to control all these components. HiL simulation platforms allow engineers to test all these components before the final car is assembled. This is done as follows: Microcontrollers, which are used in automatically controlled devices and contain the necessary control software, are connected to a high-performance computer which operates in real time. The real-time computer runs a simulation model of the system that the microcontrollers control; this may be a whole car or individual components that need to be tested. The model sends signals to the control system, which then switches on the car engine, to name but one example. The control system output signals are recorded by the computer and compared with the expected signals. You can basically use this technique for any device – metering pumps or X-ray devices – that are controlled electronically.

What are the simulation models based on?

To create simulation models, a developer will first look at the plans for the device to be developed. This provides the developer with information about the signals measured, and about the number of motors that have to be controlled. The simulation is then performed. The developer will also carry out dynamic and kinematic simulations and take into account relevant physical effects.

Where would you use hardware-in-the-loop simulations in the field of medicine?

HiL simulations are suitable for all new device developments. It speeds up development processes as it is possible to develop the mechanical system in parallel with the electronics and the control system. This helps developers to specifically detect faults in individual components. Without such a test, developers could end up in a situation where they have already assembled the device and need to find the faulty component. You can also use HiL to find out what would happen if a sensor fails without actually having to cut the wire. This considerably speeds up the development process.

Such tests are of course very useful for the regulatory approval of the devices, which requires  individual component tests as well as system tests. HiL applications would then be a component test of the control system. In addition, the Fraunhofer project group PAMB can also act as an independent assessor. We take a second look at a device that has been developed, check what the system is supposed to do and whether it actually does this.

Schematic of the hardware-in-the-loop technique. © Fraunhofer IPA

You are an expert on sensors for human application. Can you give me some examples of these kinds of sensors?

An interesting example is a blood pressure monitor of the kind people have at home. But we are more interested in measurement devices used in hospitals. In intensive care units, frequent controls are needed to find out whether a patient needs to be administered more or less of a specific drug. This is normally done by taking blood samples to test in the laboratory, which is time consuming. We are therefore looking into developing sensors that enable continuous measurements, thus doing away with laboratory tests. As intensive care unit patients are usually administered drugs intravenously, we believe that our sensors will at some time in the future also be used to determine a patient's blood values in this way. At the moment we are working on a sensor that can be used to analyse blood samples that are withdrawn by hospital staff directly at the patient bed.

Another project is the development of a stent equipped with pressure sensors. We have already made considerable progress on this. The stent will be used to measure blood pressure and monitor whether it is starting to close up again. Thirty percent of stents will close up again. At the moment, the patient's condition is taken as an indication of whether an implanted stent is still working as it is supposed to. If the patient is in a poor condition, a catheter will have to be used to find out whether the stent is still in good working order. The integration of blood pressure sensors into stents would make regular measurements possible and indicate in advance whether something is likely to go wrong. The stent signals will of course have to be transmitted to a reader outside the body, and will, of course, need to be wireless. We are planning to develop a reader the size of a cell phone. This will then be held against the body to receive signals. This is a huge challenge in terms of electrotechnical developments.

What kind of companies is your research aimed at?

The research my group is doing is aimed at automation in hospitals, for example a self-configuring operating theatre or fully automated therapy systems. We want to support companies in the development of new control units, for example. This could be a metering pump or a complete bioprocess plant. On behalf of the companies we will then think about what needs to be measured, how it can be measured and what needs to be done with the measured values.

What do patients and doctors think about automation techniques?

For patients, the main issue is a quick cure. For the doctors, it is important that automation improves their work. Just look at the so-called da Vinci surgical system - a robotic platform designed to expand surgeons' capabilities. However, it has not yet been shown to be of clinical advantage. Generally speaking, automation needs to be of demonstrable benefit for patients.

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/fraunhofer-pamb-accelerates-the-development-of-medical-devices