Steerable needles enable deeper surgery

Steerable medical needle concept

Imperial College London and maxon motors has been working on the development of steerable needles to enable more complex surgical procedures.

A significant problem when operating on the brain is trying to reach a lesion whilst avoiding obstructions.  A traditional straight needle insertion has the potential to injure an area, causing irreversible consequences, or the surgeon could deem it too dangerous to even attempt, resulting in an inoperable diagnosis. Imperial College, London has been working with maxon products to develop a groundbreaking robotic steerable needle.

Riccardo Secoli, PhD, Mechatronics in Medicine Laboratory, is part of a research team at Imperial, led by Dr Rodriguez y Baena, who are in the last year of a 5 year project, working to construct a surgical needle that can be manoeuvered to reach a target deep in the brain while avoiding critical areas. Inspired by the way certain wasps lay eggs inside plants, the unique design of this flexible, steerable needle is made of multiple segments, held together by an interlocking mechansm. The reaction force during the insertion process allows it to bend to create the curvature. The biologically inspired robotic probe, codenamed STING (Soft Tissue Intervention and Neurosurgical Guide), can change its direction smoothly by means of a “programmable bevel” tip. maxon EPOS 24/2 DC motor positioning controllers (closed-loop) are employed using a strategy first developed for car-like robots. An electromagnetic position sensor is embedded at the tip of the probe. With the aid of the maxon website, Riccardo selected a maxon EC 20 flat brushless DC motor, with a GP-22 gearhead and then contacted a maxon UK Technical Engineer to verify his selection.

Imperial College looked at other DC motor manufacturers, but a major reason to use maxon products was the access to the API (Application Programming Interface) for customisation. Imperial College are also prototyping the software, using the popular open source operating systems, the Robot Operating System (ROS), and have focussed on the API interface, using Linux in particular. maxons controllers are specifically designed to allow API customisation, which have helped the team to produce a set of libraries to make this an easy process. Maxon shares a free library for both the ARM7 and ARM6 processors, as well as DLLs (dynamic link libraries) for windows 32bit and 64bit systems.  maxon is the only supplier to manufacture the motor, gearhead and controller.

The Imperial College team has recently been awarded a prestigious €8.3M Research and Innovation Action (RIA) grant for robotic assisted neurosurgery to take this research to the next stage, with in vivo deployment expected within the next 4 years. The project, beginning on 1st April 2016, is entitled EDEN2020 and benefits from a strong industrial presence involving UK companies Renishaw plc and XoGraph Ltd.

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