A multi-channel measurement device for measuring properties of human tissue, comprising: a microcontroller; a first source/sensor complex (14,14a) comprising a first housing having a first measurement portion, a first light sensor coupled to the microcontroller and exposed to the first measurement portion, and a first plurality of light sources coupled to the microcontroller and exposed to the first measurement portion; a second source/sensor complex (14,14a) comprising a second housing having a second measurement portion, a second light sensor coupled to the microcontroller and exposed to the second measurement portion, and a second plurality of light sources coupled to the microcontroller and exposed to the second measurement portion; the first and second source/sensor complexes (14,14a) being coupled to each other such that the first measurement portion is opposite the second measurement portion and human tissue may be placed between the first and second measurement portions; the first plurality of light sources being angled such that a portion of the emitted light energy is reflected to the first light sensor and a portion of the emitted light energy is transmitted to the second light sensor by human tissue placed between the first and second measurement portions; the second plurality of light sources being angled such that a portion of the emitted light energy is reflected to the second light sensor and a portion of the emitted light energy is transmitted to the first light sensor by human tissue placed between the first and second measurement portions; the microprocessor being configured with instructions stored in non-volatile memory to individually activate each of the light sources of the first and second pluralities of light sources and to record light intensity detected by the first and second light sensors while an individual light source is activated; wherein each combination of an individually activated light source and one of the first and second light sensors provides a distinct measurement channel for measuring the absorption spectra of human blood and tissue. a microcontroller; a first source/sensor complex (14,14a) comprising a first housing having a first measurement portion, a first light sensor coupled to the microcontroller and exposed to the first measurement portion, and a first plurality of light sources coupled to the microcontroller and exposed to the first measurement portion; a second source/sensor complex (14,14a) comprising a second housing having a second measurement portion, a second light sensor coupled to the microcontroller and exposed to the second measurement portion, and a second plurality of light sources coupled to the microcontroller and exposed to the second measurement portion; the first and second source/sensor complexes (14,14a) being coupled to each other such that the first measurement portion is opposite the second measurement portion and human tissue may be placed between the first and second measurement portions; the first plurality of light sources being angled such that a portion of the emitted light energy is reflected to the first light sensor and a portion of the emitted light energy is transmitted to the second light sensor by human tissue placed between the first and second measurement portions; the second plurality of light sources being angled such that a portion of the emitted light energy is reflected to the second light sensor and a portion of the emitted light energy is transmitted to the first light sensor by human tissue placed between the first and second measurement portions; the microprocessor being configured with instructions stored in non-volatile memory to individually activate each of the light sources of the first and second pluralities of light sources and to record light intensity detected by the first and second light sensors while an individual light source is activated; wherein each combination of an individually activated light source and one of the first and second light sensors provides a distinct measurement channel for measuring the absorption spectra of human blood and tissue.