Application of a Heat- and Steam-Generating Sheet Increases Peripheral Blood Flow and Induces Parasympathetic Predominance

Figure 3

Cross-section of the sensor for measurement of the tissue total hemoglobin level and oxygen saturation. LED₁ = LED (light-emitting diode) at 750 nm (λ ₁); LED₂ = LED at 830 nm (λ ₂); distance between the light-dispatching point (light-emitting diode; LED) and the light-receiving point (photo diode; PD) = 5 mm for fingertip sensor and 30 mm for the anterior abdominal region and lumbar region sensor; 𝑙₀λ = intensity of the incident light with a wavelength of λ at time 𝑡; 𝑙λ(𝑡) = intensity of the scattered light with a wavelength of λ at time 𝑡.