Digital holographic characterization of liquid micro-lenses array fabricated in electrode-less configuration
Year: 2009
Authors: Miccio L., Vespini V., Grilli S., Paturzo M., Finizio A., De Nicola S., Ferraro P.
Autors Affiliation: CNR – Istituto Nazionale di Ottica Applicata (CNR-INOA) & Istituto di Cibernetica del CNR “E. Caianiello”, Via Campi Flegrei 34 – 80078 Pozzuoli (NA), Italy
Abstract: We show how thin liquid film on polar dielectric substrate can form an array of liquid micro-lenses. The effect is driven by the pyroelectric effect leading to a new concept in electro-wetting (EW). EW is a viable method for actuation of liquids in microfluidic systems and requires the design and fabrication of complex electrodes for suitable actuation of
liquids. When compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuitless configuration. In our case the surface electric charge induced by the thermal stimulus is able to pattern selectively the surface wettability according to geometry of the ferroelectric domains micro-engineered into the lithium niobate crystal. We show that different geometries of liquid microlenses can be obtained showing also a tuneability of the focal lenses down to 1.6 mm. Thousand of liquid microlenses, each with 100 μm diameter, can be formed and actuated. Also different geometries such as hemi-cylindrical and toroidal liquid structures can be easily obtained.
By means of a digital holography method, an accurate characterization of the micro-lenses curvature is performed and presented. The preliminary results concerning the imaging capability of the micro-lens array are also reported. Microlens array can find application in medical stereo-endoscopy, imaging, telecommunication and optical data storage too.
Journal/Review: PROCEEDINGS OF SPIE
Volume: 7389 Pages from: 73891I-1 to: 73891I-8
KeyWords: liquid microlens; digital holography; DOI: 10.1117/12.828034