One-step fabricating a PDMS optical lens based on surface charging and edge pining effects of a PDMS droplet

This paper presents a one-step method for fabricating a PDMS optical lens based on the surface charging and edge pining effects of a PDMS droplet. This method works by electrically lifting the air-liquid PDMS interface initially stabilized by the edge pining effect of a PDMS droplet on a polymethyl methacrylate (PMMA) substrate. The electrical lifting was achieved under the force interaction between the negative surface charges of the PDMS droplet and the non-uniform electric field generated by a needle-plate electrode pair. Experimental results show that the electrical lifting was achieved in about 10 seconds. With the increase of the applied electric field, the magnification of the fabricated lens increases. Fabricating a lens with a resolution of 32 lp/mm and a magnification of 23.92 times was obtained under an averaged electric field of 12500 V/cm. Chlorophyll-fluorescence-based living algae detection with the PDMS lens and a smartphone imaging system was successfully achieved.