INTRODUCTION
Congratulations on your purchase of a SonoPlot Microplotter instrument! A Microplotter system
is a leading-edge tool for the fabrication of biological microarrays, polymer electronics, or any
other application that requires precise and accurate dispensing of extremely small liquid
volumes. It can dispense picoliters of a wide variety of solutions onto almost any planar surface
in discrete spots or continuous traces such as lines or arcs.
This document will guide you through the installation and setup process for your Microplotter
system in Chapter 2, followed by walkthroughs of simple dispensing applications in Chapter 3.
The software package that controls the dispenser and automate the dispensing of patterns on a
surface, SonoGuide, will be described in Chapters 4. Solutions to common problems will be
listed in Chapter 5 and the technical specifications will be described in detail in Chapter 6. How
to refurbish a dispenser will be covered in Chapter 7.
Before that, however, it would be appropriate to describe the fundamental operating principles of
a Microplotter instrument.
Ultrasonic fluid dispensing
A Microplotter instrument is capable of applying picoliters of fluid to a surface in order to create
features as small as 20 micrometers (microns) wide due to its use of a novel form of fluid
ejection based on ultrasonic pumping.
The dispenser at the core of a Microplotter system is composed of a hollow, tapered glass
needle attached to a piezoelectric element. When an alternating current is supplied to the
piezoelectric, it vibrates. At certain frequencies, the resonant frequencies of the dispenser, a
pumping action occurs within the needle or, if the amplitudes of vibration are high enough, fluid
is sprayed out of the end of the needle. This electronically controlled pumping action makes it
possible for microscale fluid features to be put down by a Microplotter instrument. The spraying
action allows for rapid switching between different solutions while minimizing cross-
contamination.
To dispense a spot of fluid on a surface, a Microplotter dispense head is first loaded with fluid
and then brought near the surface. The ultrasonic pumping action is activated by the controlling
computer either automatically when running a preset pattern or manually by the user. This
pumping causes the fluid meniscus at the tip of the dispenser to bow outward. When the
dispenser is brought close enough to the surface, a droplet will be touched off. The ultrasonics
are then deactivated and the dispenser is retracted from the surface.
