Method for capturing a heat pattern corresponding to a fingerprint with a sensor comprising several pixels each including at least one heat-sensitive measuring element, the sensor further including at least one heating element capable of heating the heat-sensitive measuring element of each of said pixels during a measurement of the heat pattern by the heat-sensitive measuring element of said pixel, the method including at least carrying out the following steps for each of said pixels, with a finger arranged on the sensor: - a first step of heating the heat-sensitive measuring element of the pixel, in which a first amount of heating power is dissipated in the heat-sensitive measuring element of the pixel; - a first step of measuring the heat pattern present on the pixel, including a first read-out of at least one temperature variable parameter of the heat-sensitive measuring element of the pixel after a first delay time; - a second step of heating the heat-sensitive measuring element of the pixel, in which a second amount of heating power is dissipated in the heat-sensitive measuring element of the pixel; - a second step of measuring the heat pattern present on the pixel, including a second read-out of the temperature variable parameter of the heat-sensitive measuring element of the pixel after a second delay time; in which the value of the first power is different from that of the second power and/or the value of the first delay time is different from that of the second delay time, and further comprising, after the second step of measuring the heat pattern present on each of the pixels: - a step of digital processing of the first and second images of the heat pattern, corresponding respectively to all of the first measurements of the heat pattern and to all of the second measurements of the heat pattern, including at least one comparison and/or at least one linear combination of the first and second images; - a step of identification of ridges and valleys of the fingerprint from the data coming from the step of digital processing of the first and second images of the heat pattern; characterized in that it comprises, after the step of identification of the ridges and valleys of the fingerprint: - a step of calculation of a hydration level of the skin of which the heat pattern has been measured, from an abacus or a function expressing the level of hydration as a function of the result obtained during a measurement of the heat pattern for a pixel on which a ridge has been identified, or - a step of calculation of a difference in measurements between that obtained during the second measurement of the heat pattern for a first pixel on which a ridge has been identified and that obtained during the second measurement of the heat pattern for a second pixel on which a valley has been identified, then a step of calculation of a hydration level of the skin of which the heat pattern has been measured, from an abacus or from a function expressing the level of hydration as a function of the difference in measurements between a ridge and a valley of a fingerprint. - a first step of heating the heat-sensitive measuring element of the pixel, in which a first amount of heating power is dissipated in the heat-sensitive measuring element of the pixel; - a first step of measuring the heat pattern present on the pixel, including a first read-out of at least one temperature variable parameter of the heat-sensitive measuring element of the pixel after a first delay time; - a second step of heating the heat-sensitive measuring element of the pixel, in which a second amount of heating power is dissipated in the heat-sensitive measuring element of the pixel; - a second step of measuring the heat pattern present on the pixel, including a second read-out of the temperature variable parameter of the heat-sensitive measuring element of the pixel after a second delay time; - a step of digital processing of the first and second images of the heat pattern, corresponding respectively to all of the first measurements of the heat pattern and to all of the second measurements of the heat pattern, including at least one comparison and/or at least one linear combination of the first and second images; - a step of identification of ridges and valleys of the fingerprint from the data coming from the step of digital processing of the first and second images of the heat pattern; - a step of calculation of a hydration level of the skin of which the heat pattern has been measured, from an abacus or a function expressing the level of hydration as a function of the result obtained during a measurement of the heat pattern for a pixel on which a ridge has been identified, or - a step of calculation of a difference in measurements between that obtained during the second measurement of the heat pattern for a first pixel on which a ridge has been identified and that obtained during the second measurement of the heat pattern for a second pixel on which a valley has been identified, then a step of calculation of a hydration level of the skin of which the heat pattern has been measured, from an abacus or from a function expressing the level of hydration as a function of the difference in measurements between a ridge and a valley of a fingerprint.