This paper deals with a parametric study of a sensor dedicated to the microwave dielectric spectroscopy of individual particles or biological cells. The sensor is based on a coplanar topology with a capacitive gap and an embedded trap placed on top to precisely localize the particles or cells of interest. Various parameters such as the width of the capacitive gap, particle size and relative permittivity have been evaluated through simulations and validated with measurements. This study enables the optimization of the sensor in term of sensitivity.