Precision pipetting and crack-free colloidal assembly

Abstract

Applications involving millimeter and micrometer scale liquid handling combine precision instrumentation and capillary-driven fluid mechanics. This thesis develops two such applications. First, a design for a single handheld pipette that may draw and dispense liquid volumes spanning the range of an entire suite of current commercial pipettes is presented. The design, construction and validation of a proof-of-concept prototype device for this universal micropipette concept is reported, along with practical considerations for implementation and possible commercialization. Second, a direct-write method to build freestanding colloidal structures via capillary-driven self-assembly from a needle is reported. A scaling law is derived that governs the rate of assembly, as well as a criterion for the initiation of cracks, thereby explaining how to build crack-free structures over a wide range of particle sizes.