Microejector Pump

What is this patent about?

'584 is related to the field of microfluidics, specifically microejector pumps designed for generating and dispensing microdrops of liquids or suspensions. These pumps are intended for applications in chemical analysis, medical technology, and biotechnology, where precise handling of extremely small fluid volumes is crucial. Existing micropumps suffer from limitations in frequency range, delivery rate, and the ability to handle viscous fluids.

The underlying idea behind '584 is to improve the performance and versatility of microejector pumps by incorporating a diffuser element in the supply line leading to the pump chamber. This diffuser, which widens towards the chamber, enhances frequency stability, supports droplet formation during ejection, and suppresses air bubble generation during the refilling phase. The design also allows for the integration of a heater to handle viscous materials.

The claims of '584 focus on a microejector pump comprising a silicon chip with a pump chamber, a piezoelectrically actuated silicon membrane, a supply line with a diffuser element, and a discharge line with an ejection orifice. A glass chip seals the pump chamber from the silicon membrane. The key element is the diffuser element in the supply line, which improves the pump's frequency stability and droplet formation.

In practice, the microejector pump operates by applying an electrical signal to the piezoelectric actuator, causing the silicon membrane to deflect and change the volume of the pump chamber. The diffuser element ensures a stable flow of liquid into the chamber during the refill stroke and assists in the formation of microdrops during ejection. The integrated heater allows the pump to handle viscous liquids by reducing their viscosity through temperature control. The microcapillary outlet ensures the reproducible ejection of individually countable, directed, pulse-accelerated microdrops of defined volume.

The invention differentiates itself from prior approaches by using a diffuser element to improve frequency stability and droplet formation, and by integrating a heater to handle viscous fluids. Prior micropumps often relied on valves or complex nozzle designs, which could be prone to wear or limited in performance. The combination of the diffuser and heater allows the '584 pump to achieve higher delivery rates, handle a wider range of fluids, and operate more reliably than existing microejector pump designs. The silicon and glass chip construction also enables precise microfabrication and integration of other components like temperature sensors and control circuits.