Auckland Bioengineering Institute

3D force-sensitive microrobot

The 3D force-sensitive microrobot.

In order to characterise the mechanical behaviour of soft tissues, samples must be subjected to a rich set of deformations. Identification of the 3D properties of tissues requires 3D force and deformation measurements to be made simultaneously, while exposing the sample to a complete range of physiological strains. In order to provide this range of deformations, we have constructed a unique 3D force-sensitive microrobot to enable controlled deformations to be applied to soft biological tissues in vivo.

The microrobot has 3 axes driven in parallel by fast voice-coil motors, and 3 parallel force transducers capable of resolving the vector of force applied by a probe. The displacement of the probe tip is calculated from the displacement of the three axes using a forward kinematics algorithm. The probe is able to move within a 25 mm diameter spherical working volume, and record force vectors up to 20 N. The device is controlled through a LabView software interface that allows the user to specify the probe trajectory and store the acquired displacement and force data.

This device has been used to identify the dynamic mechanical behavior of skin in vivo at numerous sites on the human body. It can, however, be used to characterize the mechanical constitutive properties of any soft material larger a than 20mm cube.

Researchers and graduate students


  • Kirton, R. S. and Nielsen, P. M. F. A three axis parallel drive microrobot. Rev. Sci. Instrum. 68, 4282-4285, doi:10.1063/1.1148342 (1997).
  • Flynn, C., Taberner, A. and Nielsen, P. Mechanical characterisation of in vivo human skin using a 3D force-sensitive micro-robot and finite element analysis. Biomech model mechanobiol 10, 27-38, doi:10.1007/s10237-010-0216-8 (2011).
  • Flynn, C., Taberner, A. and Nielsen, P. Modelling the mechanical response of in vivo human skin under a rich set of deformations. Ann. Biomed. Eng. 39, 1935-1946, doi:10.1007/s10439-011-0292-7 (2011).
  • Flynn, C., Taberner, A. and Nielsen, P. Measurement of the force-displacement response of in vivo human skin under a rich set of deformations. Med. Eng. Phys. 33, 610-619, doi:10.1016/j.medengphy.2010.12.017 (2011).