A Microconcentrator and Microfilter for Suspensions such as Blood

Summary Background:

In healthcare, chemical analysis, environmental testing and other fields it is useful to separate particulate substances that are suspended in a fluid. For example separating cells from body fluids. So far, these techniques have typically required substantial capital equipment that can be both expensive and bulky, thus limiting where and when the separation can take place.

Novel technology:

The technology provides a microfluidic filter and concentrator that is capable of separating fluid from a suspension of particles. Using principles of tangential flow filtration, fluid skimming and side channel geometry, the filter separates a continuous stream of particle-free fluid without significant clogging of the device. The pressure at which the feed suspension is driven through the channel determines the rate at which the particle-free fluid is collected, and does not have an effect on the fraction of fluid collected. Thus, the device can be run at high driving pressures to obtain samples more quickly without affecting the performance of the device. The device is simple and inexpensive to make and can be made in large numbers.

Commercial Applications:

• Continuous quality testing. Tests can be conducted on the small amount of permeate removed continuously from the feed suspension. For example, testing of turbid effluent in industrial processes, the device’s resistance to clogging allows it to be integrated with downstream sensors to carry out continuous monitoring.

• Microtonal analysis systems. The filter can be combined with other devices such as micromixers, reactors, and sensors to form micro total analysis systems.

• Extraction of plasma from whole blood. The device could potentially separate plasma from whole blood. Plasma free of cells is essential for most sensitive medical diagnostic assays. A means of obtaining plasma quickly without resorting to a centrifuge is critical in developing point of care medical diagnostics.

• Continuous replacement of media. In cell culture, spent nutrient media can be removed and replaced with fresh media in order to ensure optimal growth conditions. The possibility of sealing the device completely ensures sterility, while retaining the option of continuous media replacement.

• Concentrating a suspension of particles. By continuously removing the permeate solution from a suspension, the number of particles per unit volume is increased. The technology can be used to concentrate a wide variety of suspensions.


• The device can be fabricated in polydimethylsiloxane (PDMS) in a single step. PDMS is a material that is widely studied for use in Micro total Analysis System and Lab on Chip applications.

• Permeability is controlled by geometry alone. Device engineering can control the amount of fluid extracted from the feed suspension.

• Pressure/flow-rate controls the rate of filtration and not the filtration efficiency.

• Clogging is less of a problem than in current available microfilters, as a result of the two-layered design and the high driving pressure.

Intellectual Property Status: A patent application has been filed by Harvard University and is pending.

Applications For Further Information Please Contact the Director of Business Development Daniel Behr Email: daniel_behr@harvard.edu Telephone: (617) 495-3067

Inventor(s): Stone, Howard A.

Type of Offer: Licensing

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