Supermarket shoppers squeeze fruit to see if it's ripe. The same sort of test could one day be applied to cells in a lab dish as a way of diagnosing disease. Ted Hubbard, a mechanical engineer at Dalhousie University in Halifax, Nova Scotia, has developed a pair of silicon claws small enough to squeeze individual cells just a few micrometers in diameter. Using spring-loaded joints controlled by an electrical current, the microgripper can measure the force needed to break the cells, an indicator of cellular health that could be used to test, say, blood cells for infection or cells from a biopsy to see if they are cancerous. Hubbard has shown that his device can grip dead, dry cells, and he is now developing a version able to grab live cells in liquid. He is part of a group of researchers that plans to develop, within seven years, a prototype micromachined diagnostic device incorporating the microgripper, for the lab or doctor's office.

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