Integrated particle detection chip for environmental monitoring

Abstract

This paper reports an integrated particle detection chip for low-cost and point-of-interest environmental monitoring; it consists of a micro virtual impactor and a micro corona discharger. With this system, airborne particles are introduced into the micro virtual impactor of the chip where they are classified according to their aerodynamic diameters. The particles are then charged and their number-concentration is detected in the micro corona discharger from the electrical current carried by the charged particles. The characteristics of each component were first analyzed, and the components were then integrated into a single chip. The micro virtual impactor was designed to have a cut-off diameter of 600 nm or 1.0 μm. Its classification characteristics were examined by classifying polydisperse particles–dioctyl sebacate particles ranging in diameter from 100 to 600 nm and carbon particles ranging in diameter from 0.6 to 10 μm. From the classification results, the cut-off diameter of the micro virtual impactor was measured to be either 550 nm or 1.1 μm. The micro corona discharger was fabricated based on a sharp silicon tip and a planar electrode and charged particles at 1.3 kV. Using the integrated particle detection chip comprising the micro virtual impactor and the micro corona discharger, the sensitivity for monodisperse particles—500 nm dioctyl sebacate in diameter—was measured to be 8 × 10⁻⁷ pA/(particle cm⁻³).