Source: {"pile_set_name": "USPTO Backgrounds"}

The present invention relates to a device for the measurement of the level of a chemical in a body fluid of a subject, and particularly relates to such a chemical level measurement device which is suitable for easily and conveniently measuring the level of blood sugar or urine sugar or the like.
A per se conventional such device for the measurement of the level of a chemical, such as typically sugar level, in a body fluid, such as blood or urine, of a subject is operated as follows. A piece of test paper, impregnated beforehand with a test chemical, is infiltrated with a sample of the body fluid, such as blood or urine or the like, of the subject; this test chemical should be one which reacts in a visible manner, as by changing its color or some other of its optical properties, according to the level or concentration of the relevant chemical, the level of which is to be measured, in the body fluid of the subject. Then this piece of test paper is fitted to a biochemical level measurement device, and the color or other optical property thereof is measured by said device, so as to assess the actual value of the concentration of said relevant chemical in the body fluid of the subject, i.e. so as to quantitatively evaluate the concentration of said relevant chemical. And various biochemical level measurement devices which evaluate one or more of the optical properties of such a treated piece of test paper, and which perform appropriate computations for deriving the concentration of the relevant chemical substance in the body fluid of the subject, are currently available.
Particularly, such a per se conventional biochemical level measurement device typically comprises a measurement circuit of an electronic type, and a display unit, both of these being mounted to its case, and further is provided with a test paper insertion unit which is constituted by a depression or aperture formed in its said case. This test paper insertion unit is typically provided with a test paper holding unit for holding the test paper --which typically for ease of handling is mounted on the end of a strip of flexible plate, the whole being termed a "test stick"--and with a light emitting element for illuminating said test paper and with a light receiving unit for receiving light which has been affected by said test paper, either by the action of reflection or by the action of transmission. And, typically, a cover of the test paper insertion unit can be selectively opened and closed, in order to prohibit the ingress of light from the outside of the device, which otherwise would disturb the result of the measurement.
Such a per se conventional biochemical level measurement device is capable of assessing the illumination reflected from the test paper which is impregnated with the test chemical and is infiltrated with the sample of the body fluid of the subject, or alternatively is capable of assessing the illumination transmitted through said test paper, and therefrom said device quantitatively assesses the concentration in said body fluid sample of the particular chemical substance which is being analyzed for. The result of this concentration evaluation is displayed on the display unit as a digital or as an analog value.