Have a look at our newest Advanced Materials paper on "Assembly of Multi‐Spheroid Cellular Architectures by Programmable Droplet Merging". This is a very interesting method to make arrays of complex multi-spheroid architectures (microtissues) by fusing nanoliter droplets containing single spheroids together. Double spheroids or even up to 4 spheroids can be fused together in a controlled way. Different cell types can be combined in such structures (see pictures below).
I believe it will be very useful for tissue engineering applications, studying cell-cell interactions, cell signaling, cell experiments in 3D, etc. Congratulations to Haijun!