Picolitre acoustic droplet ejection by femtosecond laser micromachined multiple-orifice membrane-based 2D ejector arrays

Described is a new method of generating droplets by using the higher-order resonance mode shape displacement of a two-dimensional (2D) silicon nitride membrane array with multiple orifices, fabricated by a femtosecond laser. This higher-order resonance ejection method increases the flow rate per membrane on a 2D ejector array and introduces the capability to eject from various locations on a membrane. Combined with the simplicity and the functionality of femtosecond laser micromachining, the novel devices are especially well suited for continuously generating picolitre droplets for various applications in biotechnology and the semiconductor industry.