PSA Levels Detected by Microfluidics Cartridge and Reader

Prostate specific antigen (PSA) levels in prostate cancer patients can be detected by a microfluidics cartridge and reader in 15 minutes. The disposable cartridge, about the size of a credit card, requires only a small drop of blood; the reader is comparable in size to a toaster.

The surface of the cartridge is covered in narrow channels, which serve as both storage for the chemicals needed for the assay and as tiny test tubes in which to carry out the reaction. Each reagent is lined up sequentially in one long channel and separated by small air bubbles. The cartridge is inserted into the reader, a vacuum pulls the blood through one channel, and reagents are delivered in appropriate sequence.

The reader uses a light-emitting diode (LED) and photodiode to detect the amount of silver, a product of the reaction, on the cartridge. The more silver, the less light passes through the chip and the higher the PSA level.

Microfluidics, which allows for the manipulation of fluids on a chip at microscopic quantities, has been limited largely to research because of its complexity and expense.

The microfluidics technology for determining patients' PSA levels was developed by Claros Diagnostics (Woburn, MA, USA). If approved by the U.S. Food and Drug Administration, the device will be one of the first examples of microfluidics-based diagnostics tests that can be performed in the hospital or doctor's office.

Scientists at Claros developed low-cost injection molding technologies that permit the hard-plastic cartridges to be made very quickly, in about 15 seconds, and for about US$0.10 apiece. The approach avoids the pumps that are used to move chemicals in other microfluidics chips, enabling a simple and robust design with no moving parts.

Clinical trials of the new device are underway and if successful the company plans to launch the device in Europe later this year and in the United States in 2011. Similar technology could be used to create screening panels for women's health or cardiac health.

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Claros Diagnostics