It is often costly and inconvenient for health care providers to send blood, urine, or other samples to a pathology lab for analysis. However, by bringing compact diagnostic equipment nearer to the patient — that is, closer to the "point of care" — it becomes much easier to test for certain disease indicators. The results can then help determine whether a more sophisticated lab analysis is warranted.

Point-of-care instruments are based on many methods, but immunochromatography in particular is finding favor for a number of diagnostic purposes. In this method, the analyte (e.g., blood) diffuses along a paper strip until it reaches a region that has been coated with an antibody that corresponds to the specific disease being tested for. If the disease is present, the antibody will bind to antigens in the blood sample.

One result of this antigen-antibody binding is that it releases some of the material that had been bound to the antibody, such as gold colloid nanoparticles. The colloid in turn produces a visible brown line on the paper strip, which can be detected with a silicon photodiode, CMOS linear image sensor, or CCD device.

An alternative approach for point of care testing, particularly in the fields of cardiology and cancer diagnosis, is to use fluorescence-based assay techniques. Because the light levels emitted in this kind of application are usually very low, photomultiplier tubes are often used as the detector, although in some cases low-noise silicon photodiodes are used instead. A new semiconductor device from Hamamatsu, the MPPC (multi-pixel photon counter), can also provide excellent detector performance for low-light-level detection.

• ICA-1000: quantitative immunochromatography instrument for quality control of strip manufacturing and for R&D of new antibody-based tests.
• ICA-2000: immunochromatography instrument for semi-quantitative point of care. Uses standard gold colloidal test strips.
• H9858 series photosensor modules: contains metal package PMT and power supply circuit. Low power consumption.
• R7400U series photomultiplier tubes: metal package PMTs with 8 mm diameter active area, available with various types of photocathodes.
• Photomultiplier tube modules for photon counting applications.
• CCD image sensors: suitable for simultaneous measurement of multiple gold colloidal lines on a test strip.
• Silicon photodiodes: suitable for transmission and reflection measurement of gold colloidal lines.
• Multi-pixel photon counters: opto-semiconductor devices with excellent photon-counting capabilities. Low-voltage operation. Modules are also available.
• Avalanche photodiodes: fast time response, low dark current, and high sensitivity photodiodes with internal gain mechanism.

Please contact us for information on other products which can be used for this application.