Design, manufacturing and implementation of a novel 2-axis force sensor for haptic applications

• A 2 degrees-of-freedom compliant mechanism for force sensing.
• A haptic interface for lungs palpation towards cancer nodules detection.
• The sizing and embodiment design as well as the characterization of the proposed solution.
• The results of palpation experiments, leading to typical force patterns associated to the presence of nodules.

Minimally invasive surgeries on the lungs have eliminated the ability for surgeons to place their hands on the patient's organ to feel for abnormalities. Therefore, in this paper, a force sensor for 2 degrees of freedom haptic applications is described. Its integration within a force feedback teleoperated device would allow the medical doctor to essentially feel the lung without making physical contact. Its design relies on a specific elastic frame. The latter is based on two flexible structures bending around the same axis, in order to reduce cross-sensitivity. The manufacturing by wire electrical discharge machining allowed to obtain a monolithic, compact and highly precise structure.The force sensor has been sized on the basis of the study of the flexible parts it is made of. Next, it has been characterized and implemented on a haptic interface reproducing the contact with a human lung. The results show that the developed sensor is adequate to the study of lung palpation.