Internal skin measurement apparatus

An internal skin measurement apparatus comprising:

• a current/voltage injection measurement unit that has a sensor including a plurality of electrodes configured to be arranged on a skin at intervals from each other;
• and
• a concentration distribution measurement unit configured to measure at least one of an electrolyte concentration distribution or a blood protein concentration distribution of a specific layer inside the skin,
• wherein the concentration distribution measurement unit includes a specific skin layer separation unit configured to calculate at least one feature as described below, the feature including information on the specific layer inside the skin and being obtained based on variation quantities of a current, a potential difference, and/or a phase measured by the current/voltage injection measurement unit,
• (1) a feature based on a variation quantity between an impedance Z1(f) between distant electrodes through which an electric field penetrates a specific skin layer and an impedance Z2(f) between close electrodes through which the electric field does not penetrate the specific skin layer but penetrates only an upper layer of the specific skin layer,
• (2) a feature based on variation quantities of a potential difference and a phase between the distant electrodes and between the close electrodes in a case where a square-wave current is applied, or a feature based on variation quantities of a current and a phase between the distant electrodes and between the close electrodes in a case where a square-wave voltage is applied, or
• (3) a feature obtained by performing predetermined processing in accordance with a threshold value based on an inter-electrode distance, amplifying a potential difference or a current including information on a concentration distribution of a target component in the specific skin layer of interest, and reducing a potential difference or a current including information on the specific skin layer of no interest, and
• the concentration distribution measurement unit includes a concentration calculation unit configured to calculate, using the feature, at least one of a conductivity, a permittivity, or a phase, which is correlated with an electrolyte concentration and a blood protein concentration in the specific layer.