A Medical Robot That Works Well Under Pressure

A number of factors — like an aging population, existing workers reaching retirement age, and education costs — are converging and leading to a shortage of healthcare professionals that is only expected to get worse in the years to come. Many of the root causes of this crisis are difficult to address, so new solutions to the problem are actively being sought out. Modern advances in machine learning and robotics, in particular, offer a lot of promise for the future. These technologies can assist medical professionals in diagnosing and treating their patients’ health conditions, effectively enabling them to do more with less.

A team of researchers at the University of Science and Technology of China believes that robots could be especially useful in diagnosing medical conditions — if only they had a better, more human-like sense of touch. Existing technologies lack the soft touch and sensitivity of human fingers, and are likely to cause injuries or rupture the soft tissue that they are examining. They also generally lack the sensitivity needed to distinguish between normal tissue and something that needs a closer look.

The researchers developed a soft robotic finger that they believe may solve these problems in the future. The finger is constructed using a combination of conductive fiber coils and liquid metal fibers. The key structural components include bending actuators, which allow the finger to move, and twisted liquid metal fibers mounted at the fingertip. Conductive coils are wound around each air chamber within the actuators, enabling precise control of the finger’s movements.

By measuring changes in electrical current as the finger bends or presses against objects, the device can detect real-time information about the force and degree of deformation. This setup enables the robotic finger to sense properties like stiffness and texture with human-like sensitivity. In addition, the twisted metal fiber at the fingertip enhances the device’s ability to recognize fine details, such as taking a patient’s pulse or identifying lumps.

The researchers tested the robotic finger through a series of experiments designed to evaluate its sensitivity and accuracy in various tasks. Initially, they brushed a feather against the fingertip to assess its ability to detect subtle changes in force. The device successfully registered a change in resistance, demonstrating its high sensitivity. Following this, the finger was tapped and pushed with a glass rod, confirming that its sensors could accurately perceive the type and intensity of the applied forces.

To test its potential for medical applications, the robotic finger was mounted on a robotic arm and used to identify three artificial lumps embedded in a silicone sheet, simulating a doctor’s examination for abnormalities. The finger pressed on the lumps, mimicking a typical medical palpation process, and successfully detected their presence. Additionally, the finger was used to locate an artery on a participant's wrist and take their pulse, further demonstrating its precision.

The device's overall design is lightweight, safe, and flexible, addressing concerns with traditional rigid robotic fingers. Future versions of the finger, with added sensors and more flexible joints, are expected to replicate the intricate movements of human fingers, making it a potentially useful tool for medical examinations in underserved areas.