Holographic 3D fabrication and manipulation using sound and light

We could show that holograms enable the shaping of acoustic fields and creation of intricate sound pressure images. These correspond to radiation force landscapes with which it is possible to assemble matter in ‘one-shot’, including biological cells. This offers new opportunities for tissue engineering directly in suspension – much faster and with far higher cell densities compared to conventional bioprinting approaches. Photocurable support media can be used to arrest the structures in space. Centimeter scale objects are possible with feature sizes in the range of hundreds of microns. Light may also be shaped by holograms and this in turn promises the ‘one-shot’ photopolymerization of objects, which are naturally at smaller scales. Differences and similarities between the acoustic and optical holographic approaches are discussed. Additional challenges arise in the case of optical holographic fields, which form in the far field and which are not easily formed as connected objects. We show that holographic 3D microfabrication can nevertheless facilitate the formation of photo-sensitive 3D structures and demonstrate single-exposure fabrication of light-actuatable micromanipulators.