Design of integrated capacitive sensors for particulate matter detection

With the aim of overcoming the issues of currently available PM sensors, in this thesis we propose a mm-scale in-flow integrated capacitive sensor of granulometry and concentration. The sensor relies on a capacitive sensor array which will be composed of a suitable number of electrodes forming planar capacitors (pixels). The electrical capacitance between electrode pairs will be affected by the airborne particles, flowing close to them, depending on the electrode geometry, the size and the relative electrical permittivity of the particles. Capacitive sensing is nowadays one of the most frequently adopted transduction methods in integrated electronic systems due to its relative simplicity of implementation, high sensitivity, high resolution, low temperature sensitivity and low noise performance. To measure the capacitance variation of each pixel and convert it into a variable that can be a voltage, a current, a frequency or a pulse width, an electronic interface is required whose specific readout architecture depends upon the system constraints, the main of which are the resolution and the measuring time. This thesis aims at developing electronic front ends for capacitive sensors with a resolution down to 10 aF.