A device for simultaneous actuation and sensing comprising: an electroactive material actuator and sensor component , having an equivalent electrical circuit of a first resistor (Rp) in parallel with the series combination of a capacitor (Cs) and a second resistor (Rs); an electrode arrangement; a current sensor for sensing a current flowing to the component; a current source for controlling a current through the component; means for determining a voltage at the component; a controller adapted to provide an actuation signal to the electrode arrangement, which comprises an activation period for charging the component, wherein the controller is further adapted to: determine a resistance of the first resistor (Rp) by sensing a steady state current during the activation period; determine a capacitance of the capacitor (Cs) by determining a charge flow during charging of the component at the beginning of the activation period, and taking into account the resistance of the first resistor; and determine a resistance of the second resistor (Rs) by controlling a current through the component using the current source during charging or discharging to have an oscillating profile and determining a phase relationship between the current sensed by the current sensor and a voltage measured by the voltage meter. an electroactive material actuator and sensor component , having an equivalent electrical circuit of a first resistor (Rp) in parallel with the series combination of a capacitor (Cs) and a second resistor (Rs); an electrode arrangement; a current sensor for sensing a current flowing to the component; a current source for controlling a current through the component; means for determining a voltage at the component; a controller adapted to provide an actuation signal to the electrode arrangement, which comprises an activation period for charging the component, wherein the controller is further adapted to: determine a resistance of the first resistor (Rp) by sensing a steady state current during the activation period; determine a capacitance of the capacitor (Cs) by determining a charge flow during charging of the component at the beginning of the activation period, and taking into account the resistance of the first resistor; and determine a resistance of the second resistor (Rs) by controlling a current through the component using the current source during charging or discharging to have an oscillating profile and determining a phase relationship between the current sensed by the current sensor and a voltage measured by the voltage meter. determine a resistance of the first resistor (Rp) by sensing a steady state current during the activation period; determine a capacitance of the capacitor (Cs) by determining a charge flow during charging of the component at the beginning of the activation period, and taking into account the resistance of the first resistor; and determine a resistance of the second resistor (Rs) by controlling a current through the component using the current source during charging or discharging to have an oscillating profile and determining a phase relationship between the current sensed by the current sensor and a voltage measured by the voltage meter. <EOS>