So-called heart-on-a-chip systems may enable scientists to evaluate the safety and efficacy of new drugs more accurately than they can with animal tests.

The new "heart-on-a-chip" device, developed by a team from the National Institute of Standards and Technology (NIST), mimics the interactions of cells within a human heart. The researchers say the technology could be used to study heart disease, which is the leading cause of death in the U.S.