By By Travis Schneider, Product Manager, Automation Group, Parker Hannifin
The microplate is a standard tool in analytical research and clinical di- agnostic testing laboratories. Since
the first 12-well plates were developed in
the 1950s, plate densities have increased
steadily, and their use and popularity
has grown exponentially. As well density
and the amounts of material tested have
grown, so has the need for automated
plate handling equipment.
A microplate is characterized by
the number of wells it contains. These
wells are always arranged in a rectangle format with a row to column ratio
of 2: 3. Although plate dimensions can
vary slightly from one manufacturer to
another, a typical microplate measures
3. 3 by 5 inches. Plate height varies with
density; low density plates have deeper
wells than higher density plates. Given
that the well spacing of a plate remains
constant, the distance between wells
for a given plate decreases with density.
Standard, commercially available microplates can have well densities of 6, 24,
96, 384, or 1,536. Although higher density plates with 3,456 and 9,600 wells have
been fabricated, they are not considered
standard within the industry.
Properly designed automation systems can be invaluable in plate handling,
offering users a variety of advantages
over manual processes:
• Higher plate throughput – Com-
mercially available robotic-assisted
analyzers can process an entire
96-well plate in less than 3 minutes, a
384-well plate in less than 15 minutes,
and a 1,536-well plate in less than
an hour. As the pressure to increase
testing throughput grows, these times
are likely to shrink still further.
• More accurate, more tightly controlled testing – Temperatures, flow
rates, volumes, speeds, and times can
all be digitally controlled with high
precision, allowing users to optimize a
given test, improving overall efficiency.
• Higher assay consistency – Because automated systems allow for
the digital control of all aspects of
an assay, an assay conducted on one
plate can be replicated very accurately
• Parameter adjustment and digital
recording – Automation simplifies
“dialing in” parameters and keeping a
digital record, which simplifies documentation and record-keeping.
• Lower assay volume – By keeping
tight control over fluid and motion
control, an automated analyzer
reduces waste, which allows conducting assays with smaller volumes and
• Lower operational cost – Despite higher upfront costs relative to
manual analysis, automated systems
are actually more cost-effective in
the long run, when one compares
the quantity and quality of tests an
automated system can perform vs. a
• Improved workplace safety –
Direct contact with some reagents
used in diagnostic equipment can be
quite hazardous. Automated systems
limit technicians’ exposure to these
• Improved process quality – Tech-
nicians dispensing liquids manually are
subject to fatigue and error; automat-
ed fluid and motion control systems
aren’t. Also if the motion and fluid
control system is designed properly, it
should significantly limit the likelihood
of crossover into an adjacent well.
• Reduced process bottlenecks –
Automating the assay frees up technicians to work on other operations
and maintain smoother process flow
within the lab.
• Lights-out operation – Automated systems don’t require bathroom
breaks, lunchtimes, or vacations.
Other than scheduled preventative
maintenance, automated systems
don’t require downtime.
Although the potential benefits of
automating the testing of microplates
are obvious, it’s critical to be cautious
about how any given technology is
applied to a diagnostic equipment
challenge to prevent later problems or
unnecessary cost. For example, every
instrument design or modification
should begin with an assessment of
the critical performance specifications.
Payload, precision, throughput, duty
cycle and expected life are among the
questions a designer should ask when
optimizing a motion system for handling microplates.
The 96-well plate is the most common
form factor used in laboratories today.