Controlled deposition of picoliter amounts of fluid using an ultrasonically driven micropipette

Abstract

A fluid microplotter that uses ultrasonics to deposit small fluid features has been constructed. It consists of a dispenser, composed of a micropipette fastened to a piece of lead zirconate titanate piezoelectric, attached to a precision positioning system. When an electrical signal of the appropriate frequency and voltage is applied, solution in the tip of the micropipette wicks to the surface in a controlled fashion. The gentle pumping of fluid to the surface occurs when the micropipette is driven at frequencies in the range of 400-700 kHz. Spots with diameters smaller than several microns can be deposited in this manner. Continuous lines can also be produced. Several examples of deposited patterns and structures are described. This means of deposition represents a higher-resolution alternative to standard fluid deposition techniques in the fabrication of biological microarrays or polymer-based circuits.

Scanning Ion Conductance Microscopy

“…The material flux from the probe to the sample substrate can either be driven by electric fields, capillary forces, hydrostatic pressure, or by ultrasonic excitation. Such type of nanolithography has been successfully applied to deposit metals [56][57][58][59], chemicals [60,61], and also biological material such as DNA, proteins or other biomolecules [62][63][64][65]. A possible field of application is the construction of nanostructured biosensors.…”

Shear‐Force‐Controlled Scanning Ion Conductance Microscopy

“…The material flux from a nanopipette to a substrate can either be driven by electric fields, capillary forces, hydrostatic pressure, or by ultrasonic excitation. Such types of nanolithography have been applied successfully to deposit metals [57][58][59][60] and chemicals [61,62], as well as biological substances such as DNA, proteins, or other biomolecules [63][64][65][66][67][68]. Having the ability to deliver substances in a controlled manner through the nanopipette of a SICM opens the perspective to study the effects of local drug delivery on biological specimens, thereby providing a nanoscopic tool for the drug-induced manipulation of individual cells [69].…”

Carbon Substrates: A Stable Foundation for Biomolecular Arrays

“…In spotted arrays, the feature density is determined by both the volume of solutions of prepurified biomolecules spotted on the surface and the wettability of the surface. Robotically driven quill-or pin-based spotters deposit volumes of approximately 1 nL and typically yield arrays containing fewer than 1,000 features/cm 2 ; piezoelectrically driven pipettes can deliver volumes as small as 3 pL and produce ~20-μm-diameter spots (24). High-density, in situ synthesized arrays (i.e., microarrays) can contain greater than 100,000 features/cm 2 , and depending on the method of synthesis can contain oligonucleotides with lengths of up to 150 bases (3, 4, 25).…”