Non-invasive measurement of chemical compounds levels in human body

The paper presents a system for measuring substances in human body by a combined technique: using visible light and near infrared spectroscopy. The approach is non-invasive, attenuation of radiation by tissues is evaluated. Measurement of two chemical compounds levels is described: that of glucose and of ethylic alcohol (ethanol). The presented measuring system is self-calibrating. Due to this, it is possible to measure changes of compound concentrations in different parts of body, e.g. wrist, arms or legs. The main measurement is done in infrared light (up to 1000 nm), auxiliary ones are performed in visible light (narrow band between 600-680 nm and wide spectrum from around 420 nm to 780 nm - white light). This allows for measurement not only a compound level, but also characteristic properties of tissues in place where measurement is done. Results of measurements are provided and advantages of multi-wavelength measurements discussed.