Micromachined fluid ejector arrays for biotechnological and biomedical applications

Abstract

In this paper, we present a micromachined flextensional droplet ejector array for use to eject liquids. By placing a fluid behind one face of a vibrating circular plate that has an orifice at its center, we achieve continuous and drop-on-demand ejection of the fluid. We present results of ejection of water and isopropanol. The ejector is harmless to sensitive fluids and can be used to eject fuels, organic polymers, photoresists, low-A dielectrics, adhesives, chemical and biological samples. Micromachined two-dimensional array flextensional droplet ejectors were realized using planar silicon micromachining techniques. Typical resonant frequency of the micromachined device ranges from 400 kHz to 4.5 MHz. The ejections of water thru 4 /spl mu/m diameter orifice at 3.45 MHz and 10 /spl mu/m diameter orifice at 2.15 MHz were demonstrated by using the developed micromachined two-dimensional array ejectors. The unique features of the device are that the fluid is not pressurized, the fluid container is chemically or biologically compatible with most fluids, and the vibrating plate contains the orifice as the ejection source.