Ade And The Echo Liquid Handler - Labcyte Echo 520 User Manual

A.2

ADE and the Echo liquid handler

The requirements of low-nanoliter liquid handling in drug discovery and the
biosciences are very exacting. For the Echo liquid handler to transfer
dissolved compound droplets while maintaining strict accuracy, precision,
and throughput specifications, the ultrasound (acoustic) pulse parameters
must be adaptively calculated, and the pulse must be precisely focused near
the meniscus of the source microplate's fluid.
The primary variables that an Echo liquid handler must take into
consideration when ejecting droplets include:





The Echo liquid handler uses dynamic, real-time measurement of the fluid
properties at multiple times during a run to respond instantly and
automatically to changes in the wells. It measures the fluid and surface
properties:



A-2 Echo Liquid Handler User Manual
Volume of liquid to be transferred. The transfer volume is specified in
the transfer protocol definition.
Fluid composition. Different fluid types exhibit different behaviors
based on their surface tension, interaction with microplate plastics
and acoustic impedance (tendency to attenuate sound waves passing
through the fluid). These differences determine the sound wave,
power, timing and focus parameters required for successful ADE. All
Echo liquid handlers are pre-calibrated to optimize these parameters
for each fluid type.
Source microplate material and characteristics. A transfer protocol's
source microplate is specified in the transfer protocol definition from
a list of Labcyte validated and predefined source plates.
Well fluid fill height. The fluid fill height in a microplate well is
measured by the Echo liquid handler and used to focus the acoustic
energy near the well fluid's meniscus.
Changes in fluid composition over time. Evaporation can cause
significant changes in well volume, especially in warm or dry
environments. In addition, concentration in a DMSO-based solution
changes over time due to hydration. If the DMSO/water ratio is
known, the transfer protocol definition can include a concentration
map. When the DMSO/water ratio is unknown, it must be measured
by the Echo liquid handler.
During the survey at the beginning of the run
Immediately before each well transfer
Immediately after each well transfer