Measuring system and measuring method, in particular for determining blood glucose
View Patent ↗A measuring system for determining blood glucose includes a photometric measuring unit with a light source and a detector, and an analytical test element, to which a body fluid sample can be applied, and which can be placed in a beam path between the light source and the detector for optical detection of an analyte. For an improved multi-wavelength measurement, it is proposed that the light source includes a first emitter that can be actuated in a first wavelength range to emit pulsating alternating light and a second emitter that can be excited in a second wavelength range to emit fluorescent light.
1. A measuring system, comprising:
a photometric measuring unit comprising a light source and a detector; and
an analytical test element to which a sample of body fluid can be applied and which can be placed in a beam path between the light source and the detector for optical detection of an analyte, wherein the light source includes a first emitter that is actuated in a first wavelength range for emitting pulsed alternating light and a second emitter including a fluorescent substance that is excited by the pulsed first emitter to emit fluorescent light in a second wavelength range, wherein both emitters are jointly oriented towards a measuring surface of the test element.
2. The measuring system according to claim 1 , wherein the alternating light has a pulse duration and the fluorescent light decays with a fluorescent life cycle, and the fluorescent life cycle is multiple times greater than the pulse duration.
3. The measuring system according to claim 1 , wherein the first emitter is in the form of a light emitting diode emitting light.
4. The measuring system according to claim 3 , wherein the light emitting diode is configured to emit light in the UV range.
5. The measuring system according to claim 1 , wherein the second emitter is configured to be optically excited to emit visible fluorescent light.
6. The measuring system according to claim 1 , wherein the second emitter is applied as a fluorescent layer to an emission surface of the first emitter.
7. The measuring system according to claim 1 , wherein the detector includes a photoreceptor configured for the collective detection of the alternating and the fluorescent light.
8. The measuring system according to claim 1 , wherein the detector includes two amplifying channels configured for wavelength-selective determination of measurement values.
9. The measuring system according to claim 1 , wherein the detector includes a lock-in amplifier that is configured to be modulated with a pulse frequency of the alternating light for detecting an alternating light signal component generated by the alternating light.
10. The measuring system according to claim 1 , wherein the detector comprises an amplifier that functions as an integrator configured to detect a composite signal generated by the alternating light and the fluorescent light.
11. The measuring system according to claim 10 , wherein the detector includes a signal processor configured to determine signal components of at least one of the alternating light and the fluorescent light.
12. The measuring system according to claim 11 , wherein the signal processor is configured to subtract the alternating light signal component from the composite signal to determine the signal components.
13. The measuring system according to claim 1 , wherein the measuring unit is integrated in a hand-held device and the test element is configured as a disposable for single use in the hand-held device.
14. The measuring system according to claim 1 , wherein the test element is coupled to the light source by an optical unit and the optical coupling can be monitored by a separate signal evaluation in one of the first and second wavelength ranges.
15. The measuring system according to claim 14 , wherein the optical unit is one of a lens and an optical fiber.
16. A measuring method for determining blood glucose in a body fluid sample applied to a disposable test element, comprising:
optically scanning the test element by a photometric measuring unit comprising a light source and a detector, wherein a first emitter of the light source is actuated in a first wavelength range to emit pulsed alternating light, and a second emitter formed by a fluorescent substance is excited in a second wavelength range by the pulsed first emitter to emit fluorescent light that is superimposed on the alternating light, wherein both emitters are jointly oriented towards a measuring surface of the test element.
17. The measuring method according to claim 16 , wherein a signal component related to the alternating light is detected by a time-resolved signal detection.
18. The measuring method according to claim 16 , wherein a signal component related to the alternating light is detected by a lock-in amplifier.
19. The measuring method according to claim 16 , wherein in one wavelength range, a measurement value for an analyte in the sample is detected, and in the other wavelength range, a control value is detected for optical coupling of the test element to the measuring unit.