Design of MobIle Digit Assistive System (MIDAS): A Passive Hand Extension Exoskeleton for Post Stroke Rehabilitation

  • Titus S. Hansen
  • Chris K. Bitikofer
  • Bahram E. Sobbi
  • Joel C. PerryEmail author
Conference paper
Part of the Biosystems & Biorobotics book series (BIOSYSROB, volume 22)


Stroke often causes flexor hypertonia as well as weakness of finger extension. This limits functionality of the hand degrading independent ability to perform upper limb activities of daily living (ADL’s). Hand rehabilitation post stroke is vital to regaining functionality in the affected limb, leading to improved independence and quality of living. In this paper the development of DigEx and MIDAS passive arm orthoses are detailed. A quick-change cam system is implemented featuring one-handed cam swapping. This provides the ability to vary assistance levels to improve usability and independence for the user. Pulleys and bearings are added to reduce friction caused by mechanical contacts and material failure. Initial tests with the prototype are promising.



Special thanks to Jeremiah Schroeder for developing the cam synthesis scripts, the DigEx design team, Bridger Hopkins and Jeremiah Schroeder, for their initial redesign efforts, and Saebo Inc. for the donation of the SaeboFlex.


  1. 1.
    ONU: World population, ageing, Suggest. Cit. United Nations, Dep. Econ. Soc. Aff. Popul. Div. (2015). World Popul. Ageing, vol. United Nat, no. (ST/ESA/SER.A/390), p. 164 (2015)Google Scholar
  2. 2.
    CDC: Stroke Facts | Accessed 15 Dec 2017
  3. 3.
    Dobkin, B.H.: Rehabilitation after stroke. N. Engl. J. Med. 352(16), 1677–1684 (2005)CrossRefGoogle Scholar
  4. 4.
    Saebo: SaeboFlex / SaeboReach Details | Saebo. Accessed 15 Dec 2017
  5. 5.
    Schroeder, J.S., Perry, J.C.: Development of a series wrapping cam mechanism for energy transfer in wearable arm support applications. In: 2017 International Conference on Rehabilitation Robotics (ICORR), 17 July 2017, pp. 585–590. IEEEGoogle Scholar
  6. 6.
    Tidwell, P.H., Bandukwala, N.N., Dhande, S.G., Reinholtz, C.F., Webb, G.G.: Synthesis of Wrapping Cams. ASME J. Mech. Des. 116(2), 634–638 (1994). Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Titus S. Hansen
    • 1
  • Chris K. Bitikofer
    • 1
  • Bahram E. Sobbi
    • 1
  • Joel C. Perry
    • 1
    Email author
  1. 1.Mechanical Engineering DepartmentUniversity of IdahoMoscowUSA

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