BLOOD GLUCOSE TEST STRIPS - How do they work? PART I

1. Insert a disposable test strip into the meter, automatically turning the meter on.
2. Lance the skin with a fine sharp to produce a small blood droplet, about one mm in diameter (volume = 0.3 to 5 µl)
3. Sample the blood with the test strip, attached to the meter.
4. The meter interrogates the strip in order to measure the blood glucose concentration, typically requiring about 5-10 seconds.

The test strips described in the above procedure can be either optical, in which glucose-derived electrons effect a change in the color of an indicating dye molecule, or electrochemical, in which case the glucose-derived electrons are routed directly through the external meter, and counted. For various reasons, including accuracy and the ability to measure extremely small blood volumes, electrochemical strips have gained the advantage in recent years, and now comprise a growing majority of the test strip market.

Components of a test strip

Automatic coding

Generally, calibration codes, corresponding to a particular batch of strips, are entered into the meter by the user, either manually or through insertion of a calibration “chip,” that accompanies the strip vial. However, it is desirable to entirely bypass this process, since user error is always a possibility. Therefore, some EBGTS do not require calibration of any sort. This is generally accomplished by:

1. Precise manufacturing control of the sensitivity of the produced strips, such that their performance is highly reproducible from batch to batch. In this process, strips are rejected, and disposed of, if their performance does not meet very stringent performance criteria.
2. Adding an indicating mark to the strip that the meter can use to assign a calibration code.

Both systems are currently in use, and automatically coded strips make up an increasing share of EBGTS

Copied by permission from the "Electrochemistry Dictionary" (http://electrochem.cwru.edu/ed/dict.htm) on "04/09/12." The original material is subject to periodical changes and updates.


Tomorrow we will discuss about the Electrochemical blood glucose test strips (EBGTS) - The newest and commonest type of strips used today