UV epoxy bonding for enhanced SAW transmission and microscale acoustofluidic integration.

Surface acoustic waves (SAWs) are appealing as a means to manipulate fluids within lab-on-a-chip systems. However, current acoustofluidic devices almost universally rely on elastomeric materials, especially PDMS, that are inherently ill-suited for conveyance of elastic energy due to their strong attenuation properties. Here, we explore the use of a low-viscosity UV epoxy resin for room temperature bonding of lithium niobate (LiNbO(3)), the most widely used anisotropic piezoelectric substrate used in the generation of SAWs, to standard micromachined superstrates such as Pyrex® and silicon.

Flexible casting of modular self-aligning microfluidic assembly blocks.

The recent shift among developers of microfluidic technologies toward modularized "plug and play" construction reflects the steadily increasing realization that, for many would-be users of microfluidic tools, traditional clean-room microfabrication is prohibitively complex and/or expensive. In this work, we present an advanced modular microfluidic construction scheme in which pre-fabricated microfluidic assembly blocks (MABs) can be quickly fashioned, without expertise or specialized facilities, into sophisticated microfluidic devices for a wide range of applications. Specifically, we describe three major advances to the MAB concept: (1) rapid production and extraction of MABs using flexible casting trays, (2) use of pre-coated substrates for simultaneous assembly and bonding, and (3) modification of block design to include automatic alignment and sealing structures.

A Venturi microregulator array module for distributed pressure control.

Pressure-driven flow control systems are a critical component in many microfluidic devices. Compartmentalization of this functionality into a stand-alone module possessing a simple interface would allow reduction of the number of pneumatic interconnects required for fluidic control. Ideally, such a module would also be sufficiently compact for implementation in portable platforms.

Selective arraying of complex particle patterns.

Procedures requiring precise and accurate positioning of particles and cells have impacted a broad range of research interests including molecular detection, self-assembly and tissue and cell engineering. These fields would be greatly aided by more advanced, yet straightforward, micro-object positioning methods that are precise, scalable, responsive and flexible. We have developed an arrayed, multilayer surface patterned microfluidic device which uses laminar convective flow to actively position particles into any desired, two-dimensional, predesigned pattern.

Acoustically driven programmable liquid motion using resonance cavities.

Performance and utility of microfluidic systems are often overshadowed by the difficulties and costs associated with operation and control. As a step toward the development of a more efficient platform for microfluidic control, we present a distributed pressure generation scheme whereby independently tunable pressure sources can be simultaneously controlled by using a single acoustic source. We demonstrate how this scheme can be used to perform precise droplet positioning as well as merging, splitting, and sorting within open microfluidic networks.

An electronic Venturi-based pressure microregulator.

Microfluidic systems often use pressure-driven flow to induce fluidic motion, but control of pumps and valves can necessitate numerous external connections or an extensive external control infrastructure. Here, we describe an electronically controlled pressure microregulator that can output pressures both greater and less than atmospheric pressure over a range of 2 kPa from a single pressurized air input of 110 kPa. Multiple independently controlled microregulators integrated in one device can potentially share the same air input.