Direct Microtip Focused Electrohydrodynamic Jet Printing of Tailored Microlens Arrays on PDMS Nanofilm-Modified Substrate

Microlens arrays (MLAs) have been widely employed as key components of various functional devices. However, the high-efficiency fabrication of tailored MLAs with high numerical aperture (NA) is still a challenge. Herein, a one-step maskless fabrication method of MLAs on polydimethylsiloxane (PDMS) nanofilm modified substrate via microtip focused electrohydrodynamic jet (MFEJ) printing is developed. The MFEJ printing can effectively avoid nozzle blockage even with highly viscous UV-curable polymer. The contact angle (CA) of polymer can be controlled on different hydrophobic substrates, which are modified by treatment with PDMS, and MLAs with different NA can be realized. The polymer CA increases from 19 degrees to 73 degrees after surface modification, and the NA of MLAs correspondingly increases from 0.18 to 0.53. The MLAs diameter and focusing properties can be easily tuned by combining the printing parameters with PDMS nanofilm modification. Various patterns of MLAs with high NA are obtained by MFEJ printing. The projection experiment indicates the uniformity and excellent optical performance of the MLAs. Moreover, the fabricated MLAs can generate magnified virtual images with a magnification up to 1.72-fold. Results show that the MFEJ printing can fabricate functional and tailored MLAs with high NA on the PDMS nanofilm-modified substrate.

Automated summary

A one-step maskless fabrication method of MLAs on PDMS nanofilm modified substrate via microtip focused electrohydrodynamic jet (MFEJ) printing is developed, which can effectively avoid nozzle blockage even with highly viscous UV-curable polymer. The MLAs with different NA can be easily realized by adjusting the contact angle (CA) of the polymer on different hydrophobic substrates modified with PDMS.