| abstract |
A wearable device for use with a smart phone or tablet includes LEDs for measuring physiological parameters by modulating the LEDs and generating a near-infrared multi-wavelength optical beam. At least one LED emits at a first wavelength having a first penetration depth and at least another LED emits at a second wavelength having a second penetration depth into tissue. The device includes lenses that deliver the optical beam to the tissue, which reflects the first and second wavelengths. A receiver is configured to capture light while the LEDs are off and while at least one of the LEDs is on and to difference corresponding signals to improve a signal-to-noise ratio of the optical beam reflected from the tissue. The signal-to-noise ratio is further increased by increasing light intensity of at least one of the LEDs. The device generates an output signal representing a non-invasive measurement on blood within the tissue. |