Photo-pens: a simple and versatile tool for maskless photolithography.

We demonstrate conical pores etched in tracked glass chips for fabricating patterns at the micrometer scale. Highly fluorescent patterns based on photopolymerization of diacetylene films were formed by irradiating UV light through conical pores called "photo-pens". The properties of photopens were investigated through experiments, finite-difference-time-domain (FDTD) simulations and numerical calculations based on Fresnel equations. We show that the pattern dimensions are easily controlled by adjusting the exposure time. Thus, patterns with a range of dimensions can be fabricated without any need of changes in the pore diameter. Parallel patterning was also demonstrated by simultaneously exposing the films to photons through multiple pores in the chip. Our method provides an inexpensive, versatile, and efficient way for patterning without the use of sophisticated masks.