Microlenses are advanced optical components that can collect and focus light with high efficiency. Current techniques for fabricating microlens arrays typically require multiple labor- and energy-intensive steps including baking, developing, and etching. These approaches are limited to producing microlens arrays only on flat substrates and with comparatively low refractive indices. Some notable recent efforts have focused on producing inorganic microlenses by using biologically-inspired, environmentally friendly techniques. These calcitic microlens arrays showed some improved optical properties, namely higher refractive index and shorter focal length, but showed severe optical distortions and aberrations.
Researchers have engineered E. coli bacteria to express a new protein that leads the bacteria to display an enzyme on their outer membranes. Upon incubation with silicate, the displayed enzymes mineralize a bioglass coating around the outside of the cells. This self-assembled, bioglass-coated cells can capture and focus light, thereby behaving like microlenses.
Bacterial microlenses combine the high refractive index and short focal length of inorganic microlenses with the environmental sustainability and aberration-free nature of silica bioglasses, with the added benefit of tunability and patternability. This technology is also 10-100 times smaller than current microlenses.