A system for growing heart cells on a microscopic silicon grid that can eavesdrop on their electrical behaviour is giving scientists a much clearer picture of how the heart works and providing a way to test new drugs much more safely. Long term it could lead to the creation of a cardiac repair patch that could be "pasted in" to replace or control damaged heart tissue. The work's taking place in the lab of Harvard's Charles Lieber and he told Chris Smith about what they've been up to... Like this podcast? Please help us by supporting the Naked Scientists