According to various embodiments, there is a charging device including a first conductive layer disposed over a first dielectric layer; a second dielectric layer disposed over a first conductive layer, the second dielectric layer including a plurality of cavities, wherein each of the plurality of cavities exposes a portion of the first conductive layer; a plurality of micro-tips, wherein one of the plurality of micro-tips is disposed within each of the plurality of cavities and on the first conductive layer; a second conductive layer disposed over the second dielectric layer; and a system of interconnected air flow channels disposed in the second dielectric layer and connected to the cavities, such that air injected through an air inlet exits through the plurality of cavities. The charging device can also include one or more power supplies to apply bias voltages to the first and the second conductive layers.