A laser-microfabricated electrohydrodynamic thruster for centimeter-scale aerial robots

Interest in flying insect-sized robots is driven by their advantages over larger robots. Their small size and low weight allow for larger deployment numbers for greater coverage at the same cost. Flapping wings represent one means for generating lift, but this requires a complex and failure-prone mechanism. A simpler alternative is electrohydrodynamics (EHD) thrust, which requires no moving mechanical parts. An EHD thruster creates a stream of ions through corona discharge at a sharp emitter tip. The ions are accelerated through an electric field, where they transfer their momentum to neutral air molecules through impacts, creating thrust. Previous work reported a 30 mg aircraft able to lift its own weight that was fabricated from predominantly silicon components formed through reactive ion etching. To avoid the expense and time associated with that process, here we introduce an alternative fabrication process based on 355 nm laser micromachining. Our fabrication time, from raw materials to complete assembly, takes less than 25 minutes. Furthermore, our approach allows for greater flexibility in materials selection. Our four-thruster device measures 1.8x2.5 cm and is composed of steel emitters and a lightweight carbon fiber mesh. The device is 43 mg and measured thrust is greater than its weight.