1. The application of engineering principles to investigate biological systems, create synthetic systems, or develop materials or devices that supplement or replace natural components. The design of medical implants and prostheses is one important field of bioengineering, involving the use of artificial tissues, organs, and organ components to replace parts of the body that are damaged, lost, or malfunctioning, e.g. artificial limbs, heart valves, and heart pacemakers. Researchers are now developing so-called ‘organs on chips’, which are microchips containing human tissue cells designed to mimic the microanatomy and functions of organs, such as the heart, lungs, and kidney. They are intended to replace experimental animals, such as mice, in testing new drugs and other treatments. Other areas include work on biosensors, biomechanics, and biomimicry. See also synthetic biology; tissue engineering.

2. The application of engineering knowledge to study the living world.