The invention provides a non-invasive
skin treatment device (100) comprising an r.f. treatment
electrode (10); a return
electrode (40); an r.f. generator (20) configured and arranged such that, during treatment, an r.f. treatment
signal is applied between the r.f. treatment
electrode (10) and the return electrode (40) for heating an inner region (15) of
skin; an impedance measurement circuit (35) configured and arranged to measure, before treatment of the inner region, an initial
skin impedance (Zo) between the r.f. treatment electrode (10) and the return electrode (40); and a treatment settings determiner (30) configured and arranged to determine, before treatment of the inner region (15), treatment settings associated with the r.f. treatment
signal depending on the initial
skin impedance (Zo) and on a dimension of the r.f. treatment electrode (10) in the
contact plane, the treatment settings comprising at least one of a
treatment duration (TD) associated with a desired treatment result, and an r.f. electrical parameter associated with the r.f. treatment
signal. The skin treatment device (100) further comprises a controller (25) configured and arranged to consecutively activate the impedance measurement circuit (35) and the treatment settings determiner (30) before treatment of the inner region (15), configure the r.f. generator (20) to provide the r.f. treatment signal according to the treatment settings, and activate the r.f. generator (20) to apply the r.f. treatment signal to the inner region (15) for the
treatment duration (TD). The invention is based on the insight obtained from multiple measurements made during the creation of microscopic thermal lesions in an inner region of skin by applying r.f. measurement and treatment signals. By analyzing the histological and heating results, a relationship was obtained between the initial impedance (Zo), the dimension of the r.f. treatment electrode (10), and the treatment settings required to obtain a particular skin treatment result. This relationship has been found to be relatively constant for different subjects, different treatment locations on the body and different skin
moisture contents. The invention makes it possible to preset or predetermine, i.e. in advance, the
treatment duration (TD) and / or the r.f. electrical parameters associated with the r.f. treatment signal accurately enough to avoid undesired
skin damage during the treatment. The device can be simpler, as it is no longer essential to continuously monitor the impedance during treatment to determine the onset of undesired
skin damage, such as
ablation, which is the safety feature known from conventional devices.