Tetherless thermobiochemically actuated microgrippers — Yesterday's 'What is it?'

Above, the title of an article published online January 12, 2009 in the Proceedings of the National Academy of Sciences.

No need to smash your head against your desk trying to clear your mind enough to get it around the subject of the paper,

Henry Fountain's "Observatory" feature in the January 12, 2009 New York Times Science section explains it all for you, and follows.

The caption for the photo above, which accompanied the Times piece, reads: "The gripper closed around tissue."

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A Microscopic Tool Inspired by the Human Hand

Using the human hand as a model, scientists at Johns Hopkins University and its medical school have developed a microscopic tool that might one day be used inside the body. The tool, a clawlike gripper less than a millimeter in diameter, could grab cells from tissue for a biopsy, for example.

Most microtools for use in medical applications are operated by tethers of some kind. But the microgripper, developed by Timothy G. Leong, David H. Gracias and colleagues and described in the Proceedings of the National Academy of Sciences, is autonomous — it can be guided by a magnetic field and actuated by warming or chemicals.

In a hand, jointed fingers are arranged around a central palm, and the fingers can bend to grasp an object. The researchers mimicked this approach in their design, with six “fingers” arranged around a hexagonal “palm.” And just as in a hand, the microgripper’s fingers have rigid metal “bones” connected by flexible joints.

The joints consist of two thin layers of metal, one of which is stressed. Ordinarily the stressed layer would cause the bimetal strip to bend, but the strip is held flat and stiff by a layer of polymer. When this polymer is warmed or degraded by certain chemicals it becomes flexible, allowing the strip to bend and the gripper to close.

The researchers say that there are many hurdles to overcome in using such a device inside the body, but that the work represents “a step toward the development of biocompatible, minimally invasive, autonomous microtools.”

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OK, now you're all warmed up and ready for the abstract of the original article, which follows.

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Tetherless thermobiochemically actuated microgrippers

We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a self-contained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy).

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Closer.