Dr. Robert Merrifield

Smart surgical tools

Dr. Robert Merrifield

Olivia Gordon
March 2016

Researchers at the Hamlyn Centre for Robotic Surgery at Imperial College, London are developing a new generation of minimally invasive surgical robots.

Dr. Robert Merrifield, who helps run the research facility, explains that minimally invasive surgical robots are now widely used for routine surgery and cutting-edge projects are opening up dramatic new possibilities.

Traditional surgical robots with large robotic arms are expensive to buy, run and maintain. Dr. Merrifield explains, “ As a general trend within surgical robotics, we’re trying to develop smaller surgical robotic ‘smart tools’ which are cheaper and more accessible. What new surgical problems can we solve if we move everything down a scale and reduce the trauma to the patient? It’s well-recognised that surgical robotics provides many benefits over open surgery and traditional minimally invasive tools. ”

With current robotic keyhole surgery, for example, the typical diameter of a tool is 7-10mm, and, says Dr. Merrifield, “ that’s still quite a big incision in the body, but if you take it down a scale you can significantly reduce tissue damage and visible scars “. A future scenario might see a surgeon using a small needle with a tiny robot built into its tip to make a minute incision in the skin and perform in-situ investigative analysis like blood or cancer tests and small-scale surgical procedures.


Thanks to the latest breakthroughs in 3D printing, researchers are working on miniaturising surgical tools and adding robotic control. For example, articulated grippers which can hold onto tissue during surgery and, with a diameter of 60 microns, are smaller than the width of a human hair and almost as small as a 10 micron-wide red blood cell. Produced using a “ two photon polymerisation ” technique in which a laser joins molecules, the device could allow surgery at cellular level. “ These are very complex mechanisms that can be made incredibly small, ” says Dr. Merrifield.

He adds that such smart instruments are micron "scale" ‐ but research is being carried out to make these devices even smaller and less invasive ‐ to create "nano-robots". Another next step could be a "smart pill" or "robot pill" ‐ a pill containing a camera and syringe for delivering medicine, which is swallowed and steered into the small intestine using the body’s own natural mechanisms. A robotic pill, the PillCam ‐ a camera in the form of a pill which is a far less invasive replacement for the traditional endoscopy. The pill, once swallowed by the patient, finds its way to the gastro-intestinal tract where it gathers images, viewable remotely by the doctor.

The director of the Hamlyn Centre, Professor Guang‐Zhong Yang, is developing a device called the “i-Snake” - a small snake-like robot which, under the remote control of the surgeon, can propel itself through the body and perform gastrointestinal, gynaecological and cardiothoracic surgery. “ My dream is that in future when you go to the operating room you don’t see those robots, but they are there... there to be used to perform a specific surgical task, ” Prof. Guang-Zhong Yang has said.

The increased accessibility of "smart tools" will be game-changing, too. Dr. Merrifield explains that the use of traditional keyhole surgery tools can require extensive training, whereas “ you can add robotic control to make them more intuitive. At the moment surgical robots are accessible only by rich nations, and to have an impact on global health, the plan is to develop cheaper smart tools which have a robotic element to augment the surgeon’s skills. ” This June, as part of the first UK Robotics Week, the Hamlyn Centre will host Surgical Robot Challenge 2016, an international competition to showcase the latest innovations in the field.

The speed and efficacy of surgery will be revolutionised with new robotic devices. Currently, to detect cancer, a surgeon may perform a biopsy, removing a small part of the tissue and sending it to a lab for analysis. The problem is that getting the result can take a long time and it would be better if the surgeon knew instantaneously whether tissue was cancerous or not - so they don’t have to potentially subject the patient to two operations if follow-up is needed, and also simply to catch, analyse and address the problem there and then. “ If you’re able to observe and analyse something in situ - being able to see the results immediately - you have far greater scope for effective surgery, ” says Dr. Merrifield.

The lab is developing a robotic probe which is able to provide in situ imaging of the structure of cells and the damage caused by cancer. To achieve a clear image, the operator must press the imaging probe against tissue with a certain level of force, Dr. Merrifield explains. “ Moving the probe over the tissue with constant force is something a human just can’t do; they can’t detect the levels of force accurately enough and they can’t control their hands precisely enough. By having robotic control you can maintain a constant force, always get a good image and build up a large mosaic of the tissue so the surgeon can see the tissue affected by cancer and the tissue that isn’t. ”

And the production and costs of surgical devices will change for the better, too. Take a traditional stent graft, for instance - a device surgeons insert in the arteries of patients suffering from aneurisms to allow blood to flow through the artery normally rather than ballooning out into the aneurism. Ideally, if you need one of these devices, you need it right away. A Hamlyn Centre project is making a robot that aims to quickly, automatically create these stent grafts.

The surgeon can use a software tool developed at the Hamlyn Centre to design a stent graft based on a CT scan. Computational Fluid Dynamics can be used to simulate blood flow through the proposed stent graft to optimise the patient-specific design. The goal is to create an autonomous manufacturing robot which is able to automatically turn the finalised stent graft design into a precision-made stent graft using robotic 3D sewing, with reduced costs and manufacturing time.

Instruments like the articulated grippers will be much cheaper than the expensive large scale robots used today and probably will be disposable, single-use devices.

We should start to see some of these ideas coming into surgical use in the next decade and taking over from the current generation of surgical robots. The aim of smart tools is not to replace the surgeon, stresses Dr. Merrifield. “ We rely on the surgeon for high level decision-making and there’s also a legal aspect. If an autonomous surgical robot did something wrong, who would be responsible? The aim is not to make an autonomous surgical robot; it is how we can augment the surgeon’s skills so they can do a better job. ”