Abstract: A sensor having a converging shape (e.g., ellipsoidal) that causes a flow stream velocity to increase from the entry towards the center (narrowest region), in line to Bernoulli's principle. The sensor includes a trapped volume that can be used to detect gas molecules. The positioning of the sensor in a narrow region can expose it to higher velocity and higher ppm, which in turn lead to a better exchange of molecules between ambient and the void in front of a gas sensing element within the sensor, thereby improving the sensor's ability to detect gas molecules at lower concentrations and with a higher speed of response. The shape of the emission detection device allows for flow convergence regardless of the wind direction in 360°.