Acoustic tractor beams – from science fiction to biomedical applications

Acoustic (ultrasonic) beams are used widely in medical and engineering imaging where the focal spot size determines resolution. Similar beams are also key to techniques that use acoustic radiation forces to manipulate objects – known alternatively as acoustic tractor beams or acoustic tweezers. The concept of tractor beams was first suggested by science fiction writers and then later became a reality. To achieve this effect beams of ultrasound must be carefully shaped to create the correct local force field. Acoustic holograms lead to exquisite control of beam shape yet are static. Phased arrays of individual emitters can provide dynamic beam control but are currently lower in resolution. This talk first introduces these ideas, then explores how to make the perfect acoustic tweezer, and finally how such devices can be used for applications including the creation of artificial muscle tissue. Readily available electronic parts and 3D printing can also be used to make less capable, but low cost, devices if needed.