Computational Optofluidics & Microfluidic Microscopy

Convnetional microscopy relies on the observation of samples prepared on a glass slide. This strategy is tedious, time-consuming, and often damages the samples being observed. Oppositely, microfluidic channels are more convenient to handle sensitive material in a biocompatible, water based environment. With microfluidic microscopy a laminar liquid flow brings samples one after the other under the window of observation. This strategy not only simplifies sample preparation process, but the liquid channel also enables repeated observation of large sample populations without perturbing their natural environment or restricting movement. Microfluidic channels are commony used to count and classify cells in flow cytometers, and they are also adapted to observe small animals such as fish and fruit fly embryos, or adult C.Elegans.
With microfluidic microscopy, we can also take further advantage of flow-contorlled sample displacement as an additional degree of freedom for imaging. For instance, we can observe the same sample from different perspectives, or at various focal depths. The resulting datasets contain more information about the sample than one would obtain from a prepared slide.
Below are three examples in which sample motion in a microfluidic channel is leveraged to obtain 3D information, phase images, or extended resolution. Our research in optofluidic microscopy aims to develop inexpensive optofluidic devices (optical hardware and algorithms) that best respond to growing needs for all-optical analysis and manipulation of large cellular-size sample populations.

Example 1 : 3D deconvolution microscopy with a tilted microfluidic channel

In this experiment, a straight microfluidic channel tilted along the optical axis is placed under the objective of a microscope. By recording successive images as the sample flows along the channel axis, we can collect for each sample flowing across the imaging window, a set of intensity measurements at different focal depths. digital alignment of the defocused stack, and deconvolution to account for the system's point spread function yields volumetric images, and topological information about the sample.

A tilted microfluidic channel is placed under the objective of a microscope and tilted along the optical axis. As samples (yeast cells) flow into the channel at a constant velocity, multiple images are recorded by a camera operating at a constant frame rate. Deconvolution of the gradually defocused images yields 3D renderings of the cells.

Example 2 : 3D deconvolution microscopy with a tilted microfluidic channel

In this experiment, a straight microfluidic channel tilted along the optical axis is placed under the objective of a microscope. By recording successive images as the sample flows along the channel axis, we can collect for each sample flowing across the imaging window, a set of intensity measurements at different focal depths. digital alignment of the defocused stack, and deconvolution to account for the system's point spread function yields volumetric images, and topological information about the sample.

A tilted microfluidic channel is placed under the objective of a microscope and tilted along the optical axis. As samples (yeast cells) flow into the channel at a constant velocity, multiple images are recorded by a camera operating at a constant frame rate. Deconvolution of the gradually defocused images yields 3D renderings of the cells.

Example 3 : 3D deconvolution microscopy with a tilted microfluidic channel

In this experiment, a straight microfluidic channel tilted along the optical axis is placed under the objective of a microscope. By recording successive images as the sample flows along the channel axis, we can collect for each sample flowing across the imaging window, a set of intensity measurements at different focal depths. digital alignment of the defocused stack, and deconvolution to account for the system's point spread function yields volumetric images, and topological information about the sample.

A tilted microfluidic channel is placed under the objective of a microscope and tilted along the optical axis. As samples (yeast cells) flow into the channel at a constant velocity, multiple images are recorded by a camera operating at a constant frame rate. Deconvolution of the gradually defocused images yields 3D renderings of the cells.