Bacteria Sized Medical Microbots for Eye Surgery

So far, these devices are being used for eye surgery, but their implementation could prove useful for the treatment of many parts of the body.

Credit: © ETH Zurich – IRIS – MSRL – Fotolia.com

Many ophthalmological impairments concern a large percentage of elderly, their incident increasing with changing demographics in the developed and developing world. Ophthalmic surgery requires high dexterity and experience and is mechanically difficult due to very low applied forces and high precision that are at the limits of human perception.

The project aims at the development of microrobots as an assistive tool for minimally invasive intraocular surgery. The microrobots are injected into the vitreous cavity through the pars plana region of the eye and are observed with an ophthalmic microscope. A magnetic manipulation system, consisting of eight electromagnets in a hemispherical arrangement, controls the motion of the magnetic microrobot in five degrees of freedom. Simple surgical tools, such as hooks and needles, are used for mechanical applications inside the eye. Furthermore, the microdevices can be loaded with drugs, magnetically moved through the vitreous cavity and steered to the targeted site on the retina.

Various materials were tested to investigate the compatibility of the microrobot inside the human body. Since this biocompatibility is a property of the surface only, the microrobot body and the surface coating can be of different materials. A unique polymer that has electrical conductivity was used for this purpose. This polymer, polypyrrole (PPy), further has the unique property of being able to change its surface properties upon the application of electrical current. The suitable electrical parameters to prevent cells and other biological fluids from sticking onto the polymer surface were established, and these surfaces were tested with cells in a laboratory environment.