Cutting surgical robots down to size

A new microsurgical robot shows promise in performing highly complex and delicate operations and can even outperform human surgeons.

A new robot using an innovative construction technique has completed a successful series of mock surgeries [1]. It brings robotics onto the microscale and could provide a further leap in making delicate life-prolonging surgery easier and safer.

Longevity.Technology: The introduction of robotics into surgery has helped surgeons perform increasingly complex operations, but their size has always been a limiting factor. This new microdevice is not only easier to store and remove from the patient’s body, but it can also be more precise than human operators. By facilitating complex and delicate operations, it can have profound implications for Longevity and the safety of operations.

Size is vital in surgery. Laparoscopic surgery in which a surgeon uses a tiny camera and tools inserted into tiny incisions to perform operations has enhanced the safety of surgical procedures for both surgeons and patients over the past decade.

Robots built on those gains, assisting surgeons by allowing them to manipulate multiple tools at once with greater flexibility and precision than would otherwise have been possible.

However, a collaboration between Wyss Associate Faculty member Robert Wood, PhD and Robotics Engineer Hiroyuki Suzuki of Sony Corporation has brought them down to size thanks to a miniature remote centre of motion manipulator (the ‘mini-RCM’).

Roughly the size of a tennis ball and weighing no more than a penny, a recent issue of Nature Machine Intelligence showed that the robot successfully performed an extremely difficult mock operation.

To create their new robot, Suzuki and Wood used a manufacturing technique known as Pop-Up MEMS which had been developed in Wood’s lab. Using this process, materials can be deposited on top of one another in layers than bond together. They will then be laser cut to a specific pattern which allows a three-dimensional shape to pop up, in much the same way as you’d expect shapes to appear in a children’s pop up picture book.

This revolutionary approach makes it possible to develop complex, tiny structures on a mass scale which would have otherwise needed to be painstakingly constructed by hand.

A parallelogram shape serves as the robot’s main structure, with three fabricated linear actuators which control the movement of the robot. The result is a robot which is much smaller and lighter than any other microsurgical devices created previously.

The robot can be seen performing a series of tasks in this remarkable video. As you can see in the video the device succeeded in a number of trials designed to mimic the conditions of teleoperated surgery by connecting the mini RCM to a phantom omni device which manipulated the mini RCM by responding to the user’s hand movements.

The first test evaluated its ability against a human to trace a tiny square smaller than a millimetre. The robot proved to be steadier than a human hand reducing the rate of error by 68% compared to manual operation.

The next test was a mock replication of a retinal vein cannulation in which a surgeon had to insert a needle through the eye to inject therapeutics into the vessels at the rear of the eyeball. To do this they fabricated a silicone tube the same size as a retinal vein. The robot successfully punctured it with a needle without causing any local damage or disruption.

In addition to its efficacy in performing delicate surgical manoeuvres, the mini-RCM’s small size provides another important benefit: it is easy to set up and install and, in the case of a complication or electrical outage, the robot can be easily removed from a patient’s body.

Following on from this successful test, the researchers aim to increase the force of the robot’s actuators to cover the maximum forces you might expect during an operation and improve precision. They are also investigating the use of a laser with shorter pulses during the machining process to improve its sensing resolution.


Image credit: Wyss Institute at Harvard University