Article Text

Development of Microelectromechanical Systems (MEMS) forceps for intraocular surgery
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  1. R B Bhisitkul1,
  2. C G Keller2
  1. 1Beckman Vision Center, Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA
  2. 2MEMS Precision Instruments, Richmond, CA, USA
  1. Correspondence to: Robert B Bhisitkul MD, PhD, Beckman Vision Center, Department of Ophthalmology, University of California San Francisco, 10 Koret Way, K301, San Francisco, CA 94143, USA; bhisititsa.ucsf.edu

Abstract

Aim: To develop silicon microforceps for intraocular surgery using Microelectromechanical Systems (MEMS) technology, the application of microchip fabrication techniques for the production of controllable three dimensional devices on the micrometre scale.

Methods: Prototype MEMS forceps were designed and manufactured for intraocular surgery. Scanning electron microscopy was used to evaluate device tip construction. Designs using both thermal expansion actuators and conventional mechanical activation were tested in human cadaver eyes and in vivo rabbit eyes to assess functionality in standard vitreoretinal surgery.

Results: MEMS forceps were constructed with various tip designs ranging from 100 μm to 2 mm in length. Scanning electron microscopy confirmed accurate construction of micro features such as forceps teeth as small as tens of micrometres. In surgical testing, the silicon forceps tips were effective in surgical manoeuvres, including grasping retinal membranes and excising tissue. The mechanical actuator design on a 20 gauge handle was more operational in the intraocular environment than the thermal expansion actuator design. While handheld operation was possible, the precision of the forceps was best exploited when mounted on a three axis micromanipulator.

Conclusion: MEMS microforceps are feasible for conventional vitreoretinal surgery, and offer advances in terms of small scale, operating precision, and construction tolerance.

  • DI, deionised
  • EM, electron microscopy
  • HF, hydrofluoric acid
  • MEMS, Microelectromechanical Systems
  • MVR, microvitreoretinal
  • MEMS
  • vitrectomy
  • surgery
  • surgical instrument
  • DI, deionised
  • EM, electron microscopy
  • HF, hydrofluoric acid
  • MEMS, Microelectromechanical Systems
  • MVR, microvitreoretinal
  • MEMS
  • vitrectomy
  • surgery
  • surgical instrument

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Supplementary materials

  • Video Footage

    A video sequence accompanies this article.

    Files in this Data Supplement:

    • [view video] - Supplemental video: Surgical tests confirmed the viability of silicon as a material for intraocular instruments. The tensile properties of silicon proved to be non-distensible and not plastically deformable under conditions of standard vitreoretinal surgery. Also, silicon was found to be antireflective with standard endoillumination, aiding visibility of the small tips. In surgical manoeuvres with serrated forceps (fig 3, and video), we were able to firmly engage tissues and displace membranes without slippage. No breakage or fracture of the silicon tips was observed in multiple trials.

Footnotes

  • Financial disclosure: CGK is founder of MEMS Precision Instruments; RBB has no financial interest.

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