A Microcantilever-Based Picoliter Droplet Dispenser With Integrated Force Sensors and Electroassisted Deposition Means

• Published in: Journal of microelectromechanical systems Vol. 17; no. 5; pp. 1239 - 1253
• Main Authors: Leichle, T., Lishchynska, M., Mathieu, F., Pourciel, J.-B., Saya, D., Nicu, L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-10-2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Automatic control; Condensed matter: structure, mechanical and thermal properties; Deposition; Dispensers; Displacement measurement; Droplet; Droplets; electrodeposition; Electronic circuits; electrowetting; Exact sciences and technology; Fluidic microsystems; Force control; Force sensors; Geometry; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Liquids; Mathematical models; Mechanical instruments, equipment and techniques; microcantilever; Microfluidics; Micromechanical devices and systems; Physics; Piezoresistance; piezoresistor; Sensors; Silicon; Solid-fluid interfaces; surface patterning; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Versatility; Wetting; electrowetting; microcantilever; piezoresistor; Droplet; electrodeposition; surface patterning; Piezoresistive devices; Wetting; Industrial application; Spot size; Cantilever beam; Finite element method; Wettability; Feedback; Droplets; Modelling; Silicon; Electronic circuits; Microelectromechanical device; Cutting force; Closed loop; micro- cantilever; Force measurement; Force sensors; Experimental study; Electrocapillarity; Embedded transducer; Piezoresistance; Fluidics
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2008.927745

This paper introduces a picoliter droplet dispenser relying on an array of silicon microcantilevers. The microcantilevers bear fluidic channels, and liquid transfer is achieved by a direct contact of the cantilever tip and the surface. A high degree of control over the location and geometry of the fabricated patterns is ensured by incorporating force sensors and electroassisted deposition means, i.e., electrowetting actuation and electrospotting, to the devices. The cantilever array, a PC-controlled stage, and an electronic circuit dedicated to the piezoresistance measurements form a closed-loop system that enables the automatic displacement of the array and the control of the deposition parameters. By using an external loading chip, different liquids are loaded onto the cantilevers, enabling the parallel deposition of several entities in a single spotting run. This paper details the design of the cantilevers assisted by finite-element modeling, the fabrication of the cantilever array, and the closed-loop operation. Moreover, proof-of-concept experiments are presented to demonstrate the versatility of our deposition system in terms of deposited materials and spot sizes. The control of the spotting process, the versatility of the printed materials, and the added electroassisted features prove that this tool has a real potential for research work and industrial applications.