Designing and testing medical instruments without expensive prototypes
Complex new medical instruments often do not make it beyond the expensive and time-consuming prototype phase. With this in mind, Ewout Arkenbout developed a new, virtual development method allowing for instruments to be evaluated and adjusted at an earlier stage. On Monday 12 February, Arkenbout will be awarded his PhD at TU Delft for his work on this subject.
‘Minimally Invasive (keyhole) Surgery aims to reduce the burden on patients during operations. Specially-designed instruments should assist surgeons in this regard,’ explains Ewout Arkenbout. ‘But in practice, it is often the case that poor design choices for such instruments can complicate procedures and put the patient’s safety at risk.’
One of the focuses of Arkenbout’s PhD research was a more in-depth exploration of multi-branched instruments for endoscopic operations via natural body orifices. The removal of a tumour from the pituitary gland, where surgery is conducted via the nose, is one instance in which a multi-branched instrument can be extremely useful. Multi-branched instruments feature a shaft, out of which two or more controllable instruments emerge. An instrument such as this should make it possible for a surgeon to perform two-handed surgical operations (such as suturing and tying knots) during surgery.
‘In the past decade, dozens of prototypes of multi-branched instruments like this have been developed,’ says Arkenbout. ‘However, the developers focus too keenly on ensuring too much freedom. The degree of control that they introduce in the new instruments is therefore too complex. In most cases, the potential benefits do not weigh up against the disadvantages. As a result, the designed instruments rarely advance beyond the prototype stage.’
Developing a prototype is a time-consuming and expensive process. ‘It would be ideal if you could already evaluate your instruments in the design phase, and gain fresh insights without needing to build an expensive prototype. My solution to this problem is gesture-based design, where sensors are used to record hand and finger movements live in a test set-up. These movements are then linked to virtually-simulated instrument movements. Testing and evaluating links in this way means that it is possible to evaluate a controllable instrument without requiring a fully operational prototype. This has already been successfully tested, including in collaboration with the LUMC and AMC.’
TU Delft - Gesture-based instrument design
Comparison between a thumb-controlled 2 degrees of freedom instrument (left) and a thumb and index finger controlled 4 degrees of freedom instrument (right). Both instruments have an identical range, but the right instrument can also vary the orientation of the tip. The shown design method, 'Gesture-based design', does not require a functional prototype.
Gesture-based instrument design potentially offers a great degree of freedom when designing instruments. For example, Arkenbout has developed and evaluated a means of controlling four surgical instruments using two hands. ‘Gesture-based instrument design is a relatively cheap yet promising method that, certainly considering the current technical developments regarding measurement systems for hand and finger movements, can flourish into a design method that is easy to put into practice.’
Doctoral thesis: Arkenbout, E. (2018), Surgeon-instrument interaction: A hands-off approach, DOI: 10.4233/uuid:ed806630-efe2-4484-a5cd-2a8011912841.
More about Arkenbouts research on TU Delft’s ‘Bio-Inspired Technology Group BITE’ website.
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