Abstract: An actuator device has a temperature sensing means and a controller adapted to apply a high frequency AC signal to stimulate internal self-heating to thereby maintain a temperature of an actuator member of the device at a certain fixed temperature, this temperature being elevated with respect to an initial temperature of the actuator member. This ensures that thermal drift may be mitigated or eliminated by compensating for any changes in environmental temperature through raising or lowering the level of the heating signal.

Abstract: An electroactive material actuator is clamped along one edge (12) and has a pre-bend about a first axis (21) which is parallel to said edge and/or about a second axis which is perpendicular to said edge. The actuator expands with expansion coefficients along the first and second axes which differ by less than 20%. This combination of isotropic (or near isotropic) expansion with a pre-bend across at least one of main axes of the device (i.e. the axes which form the general plane of the actuator) gives rise to various additional operating characteristics.

Abstract: An actuator device has a temperature sensing means and a controller adapted to apply a high frequency AC signal to stimulate internal self-heating to thereby maintain a temperature of an actuator member of the device at a certain fixed temperature, this temperature being elevated with respect to an initial temperature of the actuator member. This ensures that thermal drift may be mitigated or eliminated by compensating for any changes in environmental temperature through raising or lowering the level of the heating signal.

Abstract: An actuator structure includes an electroactive material-based active layer structure which exhibits an intrinsic variation in actuation displacement as a function of temperature. A passive compensator is provided to modify a current or voltage of an electrical stimulation applied to the active layer structure as a function of temperature such as to compensate for the thermally-induced variation in actuation displacement. The passive compensator comprises a multi-layer temperature-dependent capacitor structure, and is formed by layers of a passive carrier layer structure provided coupled to the active layer structure.

Abstract: The invention relates to an interventional instrument like a catheter comprising an ultrasound unit (41) and a rotation unit (5) for rotating the ultrasound unit, wherein the rotation unit comprises an actuation element (8) being an electroactive polymer or a one-way shape memory alloy for actuating the rotation of the ultrasound unit. Since the rotation unit comprises, as an actuation element for actuating the rotation of the ultrasound unit, an electroactive polymer or a one-way shape memory alloy, the rotation unit with the actuation element can be very compact and small.

Abstract: A flow sensor comprises an electroactive material device. A driver controls the electroactive material device to deliver heat locally to the flowing medium for which the flow is to be sensed. Temperature sensing signals are obtained and these are used to derive a flow measurement. The way the heat is dissipated relates to the flow, and it is measurable based on the temperature sensing signals. The temperature sensing involves measuring an electrical characteristic which comprises an impedance or an impedance phase angle of the electroactive material device at at least a first frequency and at a second frequency different from the first frequency. The influences of temperature and pressure can in this way be decoupled so that the temperature can be measured at any pressure.

Abstract: One of the process steps in the manufacturing process of shadow masks (13) for color display tubes (1) is blackening. In this process step, the shadow mask (13) is heated for example to a temperature of at least 600° C. in a furnace in a gentle oxidative atmosphere of a mixture of carbon monoxide and carbon dioxide. Under these conditions the shadow mask (13) is covered with a layer of Fe3O4, also referred to as ‘black rust’. After this the shadow mask (13) is cooled down. The invention describes a new blackening process which has a much higher cooling rate than usual. In the present-day process, a cooling rate of 50° C./min (21) is used; this invention discloses a cooling rate of at least 500° C./min (22) or even more. This results in an improvement by at least 20% of the thermal expansion coefficient, leading to a color display tube (1) with a shadow mask (13) having a higher mechanical stability and hence to an increased picture performance.