What is a high throughput assay?

An assay or application that is initially setup is often performed manually. This is very normal as there is a technician who is involved and little technical steps are performed in a very controlled environment (the technician’s eyes are on it). However, as the number of repeats increase or if the demand for the application increases a manual process is no longer the ideal solution. Automation is then the answer to make an application robust, reproducible and independent on technician skills. Automation is available in many forms (from a handheld repetition pipet up to a BioNex Hive platform). Once the step into automation is taken, the application can be considered to be of a higher throughput. The assay can vary and is not limited to rules. Any lab related process is able to be performed in high-throughput.

What is meant by high throughput?

There is no straight forward definition of high-throughput. The definition is depending on many aspects such as the complexity of the assay, the number of samples and also the used labware and volume range. For compound screening in the traditional pharmaceutical companies, screening is done on 384 or 1536 well plates. Running 100 plates containing 1536 samples, results in 153.600 individual data points, safe to say that this is high-throughput. To compare, a bloodbank may run two completely automated DNA extractions on large volume blood (3 ml) and only be able to run 72 or 96 samples per day. This is also considered to be high-throughput.

As there is not a straight forward definition, high-throughput is more of a term used for an increased amount of actions to be performed.

Why does centrifugation during an assay make my automation more complex?

A centrifuge needs to be in balance to operate properly. This is one of the first remarks made when an operator works with a centrifuge for the first time. There are numerous examples of accidents with centrifuges because of imbalanced loading. Luckily, modern technology allows for a tolerance in balance. This makes operating a centrifuge a lot easier for an operator.

Most automated centrifuges have two buckets to load plates. But not many automated systems are equipped with a weighing station. So, when working with plates with varying volumes in it, balancing out the centrifuge becomes a problematic step. Especially since a plate handler needs to have the same access point over and over again and moving a millimeter might already cause it to crash. The HiG centrifuges have a really high imbalance tolerance of up to 100 grams, without sacrificing into the speed (up to 5.000 g) eliminating the need for weighing a plate in most assays.

How long does a centrifugation cycle take?

This depends on your application. A centrifugation step is expressed in a unit. This can be rounds per minute (rpm) or the relative centrifugal force (RCF) or times gravity (G). To convert from RPM into G, the following formula can be used:

g = (1.118*105) * R * S2

In this formula, R is radius of the centrifuge in centimeters and S is speed of the centrifuge in rpm.

Added to the centrifugation time is the time needed for acceleration to the needed maximum speed, and off course deceleration. In most assays, the centrifuge can actively decelerate, but in some assays the formed pallet is so sensitive that this is not advised. This may increase the centrifugation time tremendously. Normal acceleration and deceleration are done in less then 20 seconds. But when working with sensitive pallets, this may take up to 20 minutes since braking inside the centrifuge is completely turned off.