A fast processing route of aspheric polydimethylsiloxane lenses array (APLA) and optical characterization for smartphone microscopy

•The fabrication time can be dramatically reduced to ~30 s.•A fast processing route of aspheric polydimethylsiloxane lenses array (APLA) was developed for smartphone microscopy.•4 types of APLA were fabricated with focal lengths in the range of 7.03 mm, and 4.43 mm.•An ordinary commercial smartphone camera can be easily transformed to a low-cost, portable digital microscopy (50×magnification).

A fast processing route of aspheric polydimethylsiloxane (PDMS) lenses array (APLA) is proposed via the combined effect of inverted gravitational and heat-assisted forces. The fabrication time can be dramatically reduced to ~30 s, compared favorably to the traditional duration of ~2 hours of repeated cycles of addition-curing processes. In this paper, a low-cost flexible lens can be fabricated by repeatedly depositing, inverting, curing a hanging transparent PDMS elastomer droplet on a previously deposited curved structure. Complex structures with aspheric curve features and various focal lengths can be successfully produced and the fabricated 4 types of APLA have various focal lengths in the range of 7.03 mm, 6.00 mm, 5.33 mm, and 4.43 mm, respectively. Empirically, a direct relationship between the PDMS volume and focal lengths of the lenses can be experimentally deducted. Using these fabricated APLA, an ordinary commercial smartphone camera can be easily transformed to a low-cost, portable digital microscopy (50×magnification) such that point of care diagnostic can be implemented pervasively.