ABSTRACT
In the last chapter, we discussed a few methods to form tunable focus liquid lenses. The underlying tuning mechanism was usually electrical actuation. Another category of actuation for focal length tuning of liquid lenses is mechanical force. This chapter will describe microlenses tuned by a variety of mechanical methods. These mechanically tunable devices include lenses consisting of a thin polymer diaphragm in a chamber or a microchannel, actuated by varying the pneumatic pressure in the chamber or channel; lenses formed from liquid-liquid interfaces, actuated by environmentally stimuli-responsive hydrogels; lenses actuated via deformation of their apertures; lenses formed from swellable hydrogels; lenses tuned by changing their apertures; lenses tuned by snapping surfaces; oscillating lens arrays driven by sound waves; and strain-responsive microlens arrays.
