Screening automation levels

FIGURE 11.3 Levels of screen automation, (a) Workstation-based automation can be categorized as (1) batch automation in which plate stackers feed assay plates into each device and plate stacks are transported between devices manually and (2) automated workstations that include liquid dispensers and readers and can transfer plates between the two devices automatically, (b) In a fully automated system, transport of plates between devices is carried out by robotic arms and scheduling software. 

High-throughput screening automation exists at a variety of levels, from manual to semi-automated to fully automated turnkey systems (83). However, the types of equipment tend to be similar, and the way in which the screening process is integrated dictates the level of automation. For a brief discussion on the advantages and disadvantages of automated platforms versus workstations, see refs. 84 and 85. 

The prototype of verification system of ultrasonic flaw detector developed is described in the scheme given in figure 2. The verification operators performed with the system are as much automated as possible. The level of automatization is limited by the necessity of human reading of information on flaw detector screen, or other operations as manual adjustment of flaw detector settings. 

Labor cost. The cost of labor is difficult to estimate. It depends on whether the process is batch or continuous, the level of automation, the number of processing steps and the level of production. When synthesizing a process, it is usually only necessary to screen process options that have the same basic character (e.g. continuous), have the same level of automation, have a similar number of processing steps and the same level of production. In this case, labor costs will be common to all options and hence will not affect the comparison. 

Directed evolution relies on the analysis of large numbers of clones to enable the discovery of rare variants with unproved function. In order to analyze these large libraries, methods of screening or selection have been developed, many of which use specialized equipment or automation. These range from the use of multichannel pipettes, all the way up to robotics, depending on the level of investment [59]. Specialized robotic systems are available to perform tasks such as colony picking, cell culture, protein purification, and cell-based assays. 

Many variations on the assay exist, but the ELISA, shown schematically below, is currently highly favored because of its simplicity once established in a laboratory sensitivity, detecting about one adduct per 107 bases and ability to screen many samples because of easy automations. The current prerequisite for the assay is that DNA can be modified to sufficiently high levels with the ultimate carcinogen to make it suitably antigenic. These types of antigens have been used to raise polyclonal antibodies in rabbits (41) and monoclonal antibodies from mice (42). 

Early laboratory robots were unreliable, but today, these systems perform quite well. Today s robots simply move plates from one robot-friendly position to another, such as the entrance pad of a plate reader. These simplified movements combined with the low weight of a plate allow engineering to simplify the robot designs. As seen in industrial application of robots, robots that are defined and used for a specific application will work day in and day out quite well. It is always best to keep the automation as simple as possible to get the highest level of performance. This is usually accomplished by minimizing the number of moveable parts associated with the automation. Stackers have also become more reliable. This was due, in part, to the standardization of the microplate by an effort of the Society for Biomolecular Screening (Danbury, CT, U.S.A.) in association with the American National Standards Institute (ANSI, Washington, DC, U.S.A.), but also due to the use of simpler stacker mechanisms. Today, there are many choices for devices, workstations, and fully automated systems. The selection as to which automated devices to purchase for HTS should be driven by a clear set of specifications that define the use of the automation. The choices can be expensive, and therefore, replacement may not be possible, so it is important to choose well. 

Figure 12 Level 1/Level 2 screening system, the L-3 VIS108. An automated decision on threats is made at Level 1. Operators can examine images of rejected bags at Level 2.

HO Friestad. Rapid screening method, including automated colorimetry, for low residue levels of lin-uron and/or chloropropham in vegetables. J Assoc Off Anal Chem 57 221-225, 1974. 

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