Microfluidic jetting device with piezoelectric actuator and method for making the same

A method of operating a liquid dispersion apparatus, the method comprising:

• increasing at a first rate an electric field across a piezoelectric element positioned on a flexible membrane by applying a voltage potential between an upper electrode and a lower electrode;
• causing a mechanical deformation of the flexible membrane in the direction of a cavity in response to increasing the electric field, the cavity having been formed in a silicon substrate with the flexible membrane at least partially enclosing the cavity;
• expelling a first volume of liquid from the cavity via an outlet in response to causing the mechanical deformation of the flexible membrane;
• and
• decreasing, at a second rate, the electric field to cause the flexible membrane to relax, wherein the first rate is less than the second rate.

A method of expelling a volume of liquid, the method comprising:

• applying a voltage potential between an upper electrode and a lower electrode, the voltage potential increasing an electric field across a piezoelectric element at a first rate that causes a flexible membrane located proximate the piezoelectric element above a cavity filled with liquid to flex a first distance into the cavity;
• in response to the flexible membrane moving toward an opposite wall of the cavity, expelling the volume of the liquid from the cavity through an outlet;
• decreasing the voltage potential between the upper electrode and the lower electrode, the voltage potential decreasing the electric field across the piezoelectric element at a second rate, wherein the first rate is less than the second rate;
• and
• in response to decreasing the voltage potential, causing the flexible membrane to move away from the opposite wall of the cavity and thereby stop expelling the volume of liquid from the cavity.

A method of operating a microfluidic device, the method comprising:

• applying a voltage potential between an upper electrode and a lower electrode to generate an electric field in a piezoelectric element positioned proximate a flexible membrane and on a first side of the microfluidic device above a cavity filled with a liquid;
• causing the flexible membrane to flex into the cavity, in response to the generated electric field;
• and
• expelling a first volume of liquid through an outlet port located at the first side of the microfluidic device in response to the flexible membrane flexing into the cavity and expelling a second volume of liquid through an inlet portion located at the first side from a reservoir into the cavity.