Abstract: The invention relates to a planar heating element (1) comprising a PTC resistive structure (2), which is arranged in a defined surface region (3) of a first surface (4) of a support substrate (5), wherein electrical connection contacts (6) for connection to an electrical voltage source (7) are associated with the PTC resistive structure (2), wherein the PTC resistive structure (2)—starting from the two electrical connection contacts (6)—has at least one internal conductive trace (8) and a parallel connected, external conductive trace (9), wherein the internal conductive trace (8) has a greater resistance than the external conductive trace (9) and wherein the resistances of the internal conductive trace (8) and external conductive trace (9) are so sized that upon applying a voltage an essentially uniform temperature distribution is present within the defined surface region (3).

Abstract: A thermal flow sensor for determining flow of a medium, comprising: a substrate; first and second temperature sensors arranged on the substrate, wherein the first and second temperature sensors are embodied as heatable temperature sensors or as a first non-heatable temperature sensor, which is associated with a first heating element, and as a second non-heatable temperature sensor, which is associated with a second heating element; a power supply unit, which by means of a first signal supplies the first heatable temperature sensor or the first heating element with a first heating power determined earlier during an adjustment operation and by means of a second signal supplies the second heatable temperature sensor or the second heating element with a second heating power determined earlier in the adjustment operation; and an evaluation unit, which in a measurement operation for determining flow of the medium ascertains a temperature difference between the first temperature sensor and the second temperature sen

Abstract: A method for producing a pH half-cell by means of which, in combination with a reference electrode and an evaluation electronics unit, a pH value of a medium can be determined, comprises the following steps: applying a first structure and a second structure to a substrate, wherein the first structure is applied by means of a thin-film method and forms a resistance element having a temperature-dependent resistance value, and wherein the second structure can be employed to derive a pH-dependent potential; applying a structured passivation glass layer, wherein the passivation glass layer substantially covers the first structure and leaves the second structure substantially uncovered; applying a mixed-conducting glass, wherein the mixed-conducting glass is substantially applied to the region that was left uncovered by the passivation glass layer; and applying a pH-sensitive glass, wherein the pH-sensitive glass is applied to the mixed-conducting glass.