Methods and apparatus for forming 2-dimensional drop arrays

Inventors

Johnson, Ross

Assignees

Pattern Bioscience Inc

Abstract

Certain embodiments are directed to finite step emulsification device and/or methods that combine finite step emulsification with gradients of confinement for the formation of a 2D monolayer array of droplets with low size dispersion.

Core Innovation

The invention provides a microfluidic circuit with a droplet forming region that includes one or more channels that open into a step region, where the step region is configured for finite step emulsification. The channel is rectangular with a top, a bottom, a height of 1 to 20 µm, and a width of 2 to 60 µm, and the step region has a top, a bottom, and a height of 5 to 80 µm with a flat region extending from the channel. One of the top and the bottom of the step region is continuous with the top or bottom of the channel while the other is offset from and parallel to the top or bottom of the channel.

The microfluidic circuit further includes a ramp region having an angle of 10 to 80 degrees relative to the top or the bottom of the step region. The ramp region terminates in an imaging region having a height of 15 to 110 µm, and the imaging region is configured to collect droplets as a two-dimensional array and to provide for imaging and evaluation of the two-dimensional droplet array. The channels, the step region, and the ramp region are connected such that fluid cannot flow into the imaging region from the ramp region without first flowing through at least one of the one or more channels.

The disclosed system emphasizes integration of the microfluidic circuit with an image analysis system for imaging and evaluation of the two-dimensional droplet array, including fluorescence detection as described in the partial content. The partial content also emphasizes manufacturability using a two-piece approach that combines a lithography-produced master for the nozzle/step with a micro-milled master for the ramp/imaging, including discussion of limitations of micro-milling versus lithography for ramp features and the resulting performance. The partial content reports low size dispersion achieved by producing a uniform 2D monolayer droplet array using finite step emulsification together with the ramp region and the imaging/array region, including an example array having 2.32% coefficient of variation.

Claims Coverage

Independent claim clm-00001 covers a microfluidic circuit with a droplet forming region (channel-to-step finite step emulsification), a ramp region with a specified angular range, and an imaging region that collects droplets as a two-dimensional array for imaging and evaluation, including a flow connectivity restriction that prevents direct fluid entry into the imaging region from the ramp region. The coverage includes at least four main inventive features: finite step emulsification architecture, ramp-to-imaging geometric integration, two-dimensional array imaging/evaluation, and a connected-flow limitation that forces fluid to pass through one or more channels first.

Overall, the independent claim defines a connected microfluidic geometry that couples rectangular channels into a finite step emulsification step region, transitions through a ramp region with a specified angular range into an imaging region that collects a two-dimensional droplet array for imaging and evaluation, while restricting fluid flow so that the imaging region cannot be reached from the ramp without passing through the channels.

Stated Advantages

Documented Applications