(A) Magnets (shown in gray) offer a relatively simple and accessible method for
manipulating the position of magnetized cells [28], aligning matrix fibers [17], or patterning growth factor gradients [22]. (B) Focused optical fields (shown in red) provide high
spatial resolution that can be used for optogenetic modulation of cells [40], photodegradation of materials [34], or local release of biochemical
factors [35]. (C) Acoustic fields can be
generated by piezotransducers (shown in blue) in order to pattern bulk cell
populations [45], modulate fiber
microstructure [57], or locally release
biochemical factors [59]. Many of these
approaches, along with related technologies, are already used to engineer
complex tissue structures, while others require further development,
optimization, or scale up.