The present invention relates to a system for analyzing particles, the system comprising: a NEMS device comprising at least one NEMS sensor for detecting particles impacting the at least one NEMS sensor, each NEMS sensor comprising a NEMS sensor area, a particle lens assembly, the particle lens assembly comprising at least one particle lens for focusing particles onto a NEMS sensor of the at least one NEMS sensor, wherein the particle lens assembly is spaced from the at least one NEMS sensor area by a separation distance, wherein the system is configured to sustain a space defined between the particle lens assembly and the NEMS device at a pressure where a mean free path for a reference particle is greater than the separation distance. The present invention also relates to a corresponding method.