Multi-fingered haptic palpation utilizing granular jamming stiffness feedback actuators

Min Li, Tommaso Ranzani, Sina Sareh, Lakmal D. Seneviratne, Prokar Dasgupta, Helge A. Wurdemann, Kaspar Althoefer

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


This paper describes a multi-fingered haptic palpation method using stiffness feedback actuators for simulating tissue palpation procedures in traditional and in robot-assisted minimally invasive surgery. Soft tissue stiffness is simulated by changing the stiffness property of the actuator during palpation. For the first time, granular jamming and pneumatic air actuation are combined to realize stiffness modulation. The stiffness feedback actuator is validated by stiffness measurements in indentation tests and through stiffness discrimination based on a user study. According to the indentation test results, the introduction of a pneumatic chamber to granular jamming can amplify the stiffness variation range and reduce hysteresis of the actuator. The advantage of multi-fingered palpation using the proposed actuators is proven by the comparison of the results of the stiffness discrimination performance using two-fingered (sensitivity: 82.2%, specificity: 88.9%, positive predicative value: 80.0%, accuracy: 85.4%, time: 4.84 s) and single-fingered (sensitivity: 76.4%, specificity: 85.7%, positive predicative value: 75.3%, accuracy: 81.8%, time: 7.48 s) stiffness feedback.

Original languageBritish English
Article number095007
JournalSmart Materials and Structures
Issue number9
StatePublished - Sep 2014


  • granular jamming
  • haptic feedback
  • multi-fingered palpation
  • stiffness feedback
  • tumor identification


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