This review gives an overview of techniques used for high-resolution jet printing that rely on electrohydrodynamically induced flows. Such methods enable the direct, additive patterning of materials with a resolution that can extend below 100 nm to provide unique opportunities not only in scientific studies but also in a range of applications that includes printed electronics, tissue engineering, and photonic and plasmonic devices. Following a brief historical perspective, this review presents descriptions of the underlying processes involved in the formation of liquid cones and jets to establish critical factors in the printing process. Different printing systems that share similar principles are then described, along with key advances that have been made in the last decade. Capabilities in terms of printable materials and levels of resolution are reviewed, with a strong emphasis on areas of potential application.

Self-assembly of block-copolymers provides a route to the fabrication of small (size, <50 nm) and dense (pitch, <100 nm) features with an accuracy that approaches even the demanding specifications for nanomanufacturing set by the semiconductor industry. A key requirement for practical applications, however, is a rapid, high-resolution method for patterning block-copolymers with different molecular weights and compositions across a wafer surface, with complex geometries and diverse feature sizes. Here we demonstrate that an ultrahigh-resolution jet printing technique that exploits electrohydrodynamic effects can pattern large areas with block-copolymers based on poly(styrene-block-methyl methacrylate) with various molecular weights and compositions. The printed geometries have diameters and linewidths in the sub-500 nm range, line edge roughness as small as ∼45 nm, and thickness uniformity and repeatability that can approach molecular length scales (∼2 nm). Upon thermal annealing on bare, or chemically or topographically structured substrates, such printed patterns yield nanodomains of block-copolymers with well-defined sizes, periodicities and morphologies, in overall layouts that span dimensions from the scale of nanometres (with sizes continuously tunable between 13 nm and 20 nm) to centimetres. As well as its engineering relevance, this methodology enables systematic studies of unusual behaviours of block-copolymers in geometrically confined films.

Electrohydrodynamic jet (E-jet) printing has emerged as a high-resolution alternative to other forms of direct solution-based fabrication approaches, such as ink-jet printing. This paper discusses the design, integration and operation of a unique E-jet printing platform. The uniqueness lies in the ability to utilize multiple materials in the same overall print-head, thereby enabling increased degrees of heterogeneous integration of different functionalities on a single substrate. By utilizing multiple individual print-heads, with a carrousel indexing among them, increased material flexibility is achieved. The hardware design and system operation for a relatively inexpensive system are developed and presented. Crossover interconnects and multiple fluorescent tagged proteins, demonstrating printed electronics and biological sensing applications, respectively.

Fundamental understanding of the self-assembly of domains in block copolymers (BCPs) and capabilities in control of these processes are important for their use as nanoscale templates in various applications. This paper focuses on the self-assembly of spin-cast and printed poly(styrene-block-methyl methacrylate) BCPs on patterned surface wetting layers formed by electrohydrodynamic jet printing of random copolymer brushes. Here, end-grafted brushes that present groups of styrene and methyl methacrylate in geometries with nanoscale resolution deterministically define the morphologies of BCP nanostructures. The materials and methods can also be integrated with lithographically defined templates for directed self-assembly of BCPs at multiple length scales. The results provide not only engineering routes to controlled formation of complex patterns but also vehicles for experimental and simulation studies of the effects of chemical transitions on the processes of self-assembly. In particular, we show that the methodology developed here provides the means to explore exotic phenomena displayed by the wetting behavior of BCPs, where 3-D soft confinement, chain elasticity, interfacial energies, and substrate's surface energy cooperate to yield nonclassical wetting behavior.