Abstract: The invention relates to sweat activity measurement, e.g. for determining a physiological state of a subject, embodied by a method as well as a kit with an immittance measuring circuit and electrodes with contact electrolyte. Sweat activity is considered a transport phenomenon and can be defined as a flux, e.g. gram water per skin area per second. Prior art methods determining water absorbed per gram dry stratum corneum measures skin moisture and do not truly reflect sweat activity. A periodic signal with frequency of 60 Hz or lower is applied to reduce contribution from complex admittance of the skin, and skin conductance is measured as a degree of sweat activity. The contact electrolyte allows filling of sweat ducts with sweat from sweat glands, this may be characterized in that it does not substantially fill the sweat ducts when being positioned on the skin and/or in that it has a re-absorption time constant from the sweat ducts into the Epidermis of less than 15 min.

Abstract: The invention relates to sweat activity measurement, e.g. for determining a physiological state of a subject, embodied by a method as well as a kit with an immittance measuring circuit and electrodes with contact electrolyte. Sweat activity is considered a transport phenomenon and can be defined as a flux, e.g. gram water per skin area per second. Prior art methods determining water absorbed per gram dry stratum corneum measures skin moisture and do not truly reflect sweat activity. A periodic signal with frequency of 60 Hz or lower is applied to reduce contribution from complex admittance of the skin, and skin conductance is measured as a degree of sweat activity. The contact electrolyte allows filling of sweat ducts with sweat from sweat glands, this may be characterized in that it does not substantially fill the sweat ducts when being positioned on the skin and/or in that it has a re-absorption time constant from the sweat ducts into the Epidermis of less than 15 min.

Abstract: The invention relates to apparatus and methods for measuring local tissue impedance for subcutaneous tissue surrounding a needle tip inserted into a subject, impedance spectra and/or complex impedance values are determined. The invention applies a monopolar impedance measuring setup with a needle, a current-carrying electrode, an optional reference electrode. The setup is configured to eliminate contributions from the current-carrying electrode in order to measure local impedance of tissue in the close neighbourhood of the needle tip instead of an averaged value over the volume or current path between the needle and the electrode(s). The determined impedance can be correlated with either a tissue type or state, or with a position of the needle tip in the subject, and can thereby provide an insertion history to the operator in the form of impedance or corresponding tissue type as a function of insertion depth or time.