The Effect of the Orientation Towards Analyte Flow on Electrochemical Sensor Performance and Current Fluctuations Analyte flow influences the performance of every gas sensor; thus, most of these sensors usually contain a diffusion barrier (layer, cover, inlet) that can prevent the negative impact of a sudden change of direction andor the rate of analyte flow, as well as various unwanted impacts from the surrounding environment. However, several measurement techniques use the modulation of the flow rate to enhance sensor properties or to extract more information about the chemical processes that occur on a sensitive layer or a working electrode. The paper deals with the experimental study on how the analyte flow rate and the orientation of the electrochemical sensor towards the analyte flow direction influence sensor performance and current fluctuations. Experiments were carried out on a semiplanar, threeelectrode topology that enabled a direct exposure of the working (sensing) electrode to the analyte without any artificial diffusion barrier. The sensor was tested within the flow rate range of 0.1xe2x80x931 Lmin and the orientation of the sensor towards the analyte flow direction was gradually set to the four angles 0xc2xb0, 45xc2xb0, 90xc2xb0 and 270xc2xb0 in the middle of the test chamber, while the sensor was also investigated in the standard position at the bottom of the chamber.

Open loop testing for optimizing the closed loop operation of chemical systems Abstract   One way to optimize the operation of chemical systems consists on using closed loop controls while the system is operated. This way, it is possible to optimize the operating point in the plant, process or chemical system so that certain quantities are maximizedminimized or time responses are reduced. In the design of the closed loop controls, though, one of the problems is the large number of configuration parameters involved and the uncertainties in the system. The objective of this paper is to present how recently proposed controls, exploiting timescale separation, allow to configure their closed loop configuration parameters from openloop measurements. These controls have been proposed to accelerate the time response of metaloxide gas sensors by operating at constant surface potential. The main result of the paper explains the link between the open loop measurements and closed loop operation. Experiments are provided using a commercial offtheshelf Microelectromechanical gas sensor.