Surgical Tribune Asia Pacific

New device improves surgeon’s sensitivity during operations

By Surgical Tribune
September 05, 2016

HIROSHIMA, Japan: A small vibrating device added to surgical tools could improve surgeons’ sensitivity to different tissue shapes and textures in their patients’ bodies. Japanese researchers have designed the PZT Actuator to attach to any existing hand-held surgical tool for immediate use, without doctors requiring extra training.

Laparoscopic surgery benefits patients by reducing the size of surgical incisions and minimising scarring. However, surgeons cannot use their fingers to directly touch patients to obtain essential information about their organs.

A research team from Hiroshima, including mathematical and medical engineers, has developed and is currently testing a vibrator called the PZT Actuator. The device attaches to a surgical tool and vibrates in the surgeon’s palm at a constant rate. The vibrations are so subtle they cannot be sensed. However, this constant, uniform vibration enhances the surgeon’s sensitivity to other, irregular sensations. The natural variations between touching different tissues with a metal tool may normally be too subtle for the surgeon to detect, but the constant vibrations from the PZT Actuator boost the sensation to a noticeable level.

“We started this work six years ago, trying to enhance human fingertip sensitivity, but in 2012 I had the idea that increased sensitivity could be valuable during minimally invasive surgeries. Typical medical tools obtain information about the patient’s condition. There are very few devices that aim to enhance the doctor’s skill,” said Dr Yuichi Kurita, lead author of the study and an associate professor in the Department of System Cybernetics of the Faculty of Engineering at Hiroshima University.

The researchers first tested the device through mathematical modelling using calculations of four types of neurons and their response to different levels of mechanical stimulation. The mathematical term for the phenomenon of a constant undetectable signal enhancing a simultaneous irregular signal is the stochastic resonance effect.

During practical tests, volunteers were blindfolded and asked to use surgical forceps with the PZT Actuator attached to identify different textures of sandpaper and find a small Styrofoam ball inside a cup filled with silicone. These tests simulated detecting tissue texture and identifying a solid tumour.

According to the researchers, the results of these tests and other analyses indicated that there is a range of vibration intensity that significantly improves anyone’s sensitivity. The tool does not need to be fine-tuned to each user’s unique sense of touch, meaning the PZT Actuator should be robust and simple to use.

The researchers state that the PZT Actuator remains safe for patients because the device is attached only to the handles of the surgeon’s tools and does not enter the patient’s body. The vibrations are so subtle that they do not shake the tool. The electrical power supply too is safe for doctors and patients.

“Our next set of experiments will confirm the usefulness of the PZT Actuator in surgical situations. Before we can give this tool to surgeons, we must also develop a method to maintain good hygiene of the device so it is always safe for patients,” said Kurita.

The study, titled “Surgical grasping forceps with enhanced sensorimotor capability via the stochastic resonance effect”, was published on 14 July in IEEE/ASME Transactions on Mechatronics ahead of print.

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