Portable flow cytometers, especially in handheld or briefcase sizes, have not been available. One reason is the need to support complex, high-pressure fluidics and process cells using a centrifuge and mixing device. A need existed for point-of-care and/or point-of-analysis flow cytometry.
A component for a miniature flow cytometer has been developed that enumerates specific cell types in a mixture of suspended, usually labeled, biological cells. The invention is a device for the automated preparation and passing through microchannels of blood cells and other types of biological cells in liquid suspension. It comprises a device for obtaining and processing (including labeling) cell-containing samples for detecting and enumerating by appropriate optical sensing devices. In one embodiment, the device for processing and labeling also samples processes and samples small volumes, such as a drop of blood.
The cartridge consists of two parts: an up-front fluid processor and a microfluidic chip. The processing unit may be fabricated by rapid prototyping, while the microfluidic branching system is fabricated using standard molding of poly-dimethylsiloxane (PDMS) against an etched SU-8 silicon mold.
The buffer for pushing two flows is loaded into two cylinders, all the way up to a rotating valve that determines the volume of blood and the volume of reagent to be mixed. Reagent is loaded into the large passage through the valve via a septum. The user or patient places a lancet-punctured finger at the sample inlet on the side of the cartridge, turns the valve 90°, and removes the retainer before inserting the cartridge into the cytometer. There are stops to limit the valve to only these two positions. The rest of the process is automated, and begins when the user has inserted the cartridge into a miniature cytometer and engages the operating electronics, including an actuator that pushes both pistons in the buffer cylinders. Drains are vented to atmosphere by means of a hydrophilic membrane.
The disposable cartridge includes optional means of disposing of waste fluids. The cartridge can exist in handheld versions, hand-carried versions, and versions intended for bench-scale optical reading devices. It contains all of the fluids required for flow cytometric analysis so that an optical reading device does not need to contain fluids. The cartridge may consist of modules that include single-use components that include the sampling and processing device and the multichannel microfluidics device.