Determining a water and a lipid level of skin

A system for determining a water and a lipid level of skin, the system comprising:

• at least two electrodes suitable for contacting skin;
• and
• a signal generator configured to generate an electrical signal at a frequency across the at least two electrodes,
• wherein the signal generator is configured to generate an electrical signal at a first frequency in a first frequency range and the system is configured to determine a water level of skin based on the measured conductivity when the frequency of the signal is the first frequency, wherein the first frequency range is a frequency range from 10 kHz to 100 kHz or a frequency range from 0.8 MHz to 5 MHz, wherein the first frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is lower so that the skin conductivity is less sensitive to the lipid level;
• and
• wherein the signal generator is configured to generate an electrical signal at a second frequency in a second frequency range and the system is configured to determine a lipid level of skin based on the measured conductivity when the frequency of the signal is the second frequency, wherein the second frequency range is a frequency range from 10 Hz to 500 Hz or a frequency range from 10 MHz to 100 MHz, wherein the second frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is higher so that the skin conductivity is more sensitive to the lipid level;
• and
• wherein the system is configured to:
• measure a conductivity between the at least two electrodes;
• compare the measured conductivity to one or more predefined profiles describing the manner in which skin conductivity varies with frequency;
• and
• determine a water and a lipid level of skin based on the comparison of the measured conductivity and the frequency of the radio frequency signal.

A method of operating a system to determine a water or lipid level of skin, the system comprising at least two electrodes suitable for contacting skin and a signal generator configured to generate an electrical signal across the at least two electrodes at a frequency, wherein the method comprises:

• generating an electrical signal at a first frequency in a first frequency range, wherein the first frequency range is a frequency range from 10 kHz to 100 kHz or a frequency range from 0.8 MHz to 5 MHz, wherein the first frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is lower so that the skin conductivity is less sensitive to the lipid level;
• measuring the conductivity between the at least two electrodes;
• generating an electrical signal at a second frequency in a second frequency range, wherein the second frequency range is a frequency range from 10 Hz to 500 Hz or a frequency range from 10 MHz to 100 MHz, wherein the second frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is higher so that the skin conductivity is more sensitive to the lipid level;
• and
• measuring a conductivity between the at least two electrodes;
• and
• comparing the measured conductivity to one or more predefined profiles describing the manner in which skin conductivity varies with frequency;
• and
• determining a water and a lipid level of skin based on the comparison of the measured conductivity and the frequency of the radio frequency signal.