Medical devices: adaptive limb control, helium-free magnets

Every user of a prosthesis or exoskeleton walks differently

What happens. A powered prosthesis or exoskeleton is set for an average user. Each wearer has a different gait, body weight, speed and way of moving, and the same person walks differently on stairs, slopes and level ground.

What it costs. Comfort and safety. If the device does not move with the wearer, it is tiring, can cause falls and gets switched off.

Why the usual fix fails. Fitting by the orthopaedic technician is done once, in the clinic, on level ground. A fixed controller with many adjustable parameters leaves the work to someone who has little time for it.

How a fixed-price remote diagnosis checks it. From gait recordings, joint angles, forces and motor signals I check how much users differ and whether a model-based adaptive controller could follow them within safe limits. The fixed-price remote diagnosis shows what data you would need and what remains for later clinical validation.

Background: Control that adapts to drift and wear

Helium-free imaging magnets behave thermally in a new way

What happens. Magnetic resonance scanners are moving to sealed magnets with little helium or none, cooled by cryocoolers through conduction. They have much less cold liquid to absorb a disturbance, so their temperature reacts faster.

What it costs. Reliability: a magnet that warms up during a power cut, a cryocooler fault or a heavy gradient load can lose field or need a long recovery.

Why the usual fix fails. The cooling design of liquid-helium systems does not carry over. Safe margins in the cooling capacity make the system bigger and more expensive.

How a fixed-price remote diagnosis checks it. From the thermal design, cryocooler data and test-bench measurements I build a thermal model of the magnet and its cooling and test how it rides through disturbances. The fixed-price remote diagnosis shows what a thermal control and ride-through concept would need to cover for your design.

Background: Predictive control of process plants

Medical device rules add certification work for engineering teams

What happens. The European rules for medical devices have long transition periods, but the end dates are coming closer (Dutch health inspectorate). Notified bodies needed extra time to certify devices, and manufacturers have to document and verify the control software and the models behind a device.

What it costs. Engineering capacity is tied up in certification and not available for development, and the evidence that a device behaves as claimed has to be reproducible.

Why the usual fix fails. Hiring more regulatory staff does not give verified models of the control. Verifying a controller only by tests on the device leaves gaps in coverage.

How a fixed-price remote diagnosis checks it. I review the control software and its models independently from the documentation, simulations and test data you already have. The fixed-price remote diagnosis shows where verification is complete, where evidence is missing and what to add before the notified body asks.