Liquid Handling · 2023
Technical upgrade of an open-source liquid handler to support bacterial colony screening
The optimization of genetically engineered biological constructs is a key step to deliver high-impact biotechnological applications. The use of high-throughput DNA assembly methods allows the construction of enough genotypic variants to successfully cover the target design space.
Performance the paper reports
0 of 5- Motion—Motion accuracy: not reported
- Volume—Volumetric accuracy: not reported
- Viability—Cell viability: not reported
- Unattended—Unattended operation: not reported
- Standard—Standard compliance: not reported
The full text was read and states no figure for any of the five.
How hard this is to adopt
3.3 of 5, higher is easierEach score is shown against the range the other 59 builds actually occupy, because no criterion uses the full 1–5 scale. These describe how reproducible the build is, not how good the science is.
Resolution
3/1–5No dispense volumes or flow rates characterised; picking tolerance ~1 mm and colonies under 1 mm fail; pipetting resolution is inherited entirely from the host OT-2 P20.
Throughput
3/2–5Single P20 pipette picking one colony at a time from one plate into a 96-format tray, with no independent parallel channels.
Parts sourcing
3/2–4Mix of common parts and custom/printed components.
Skill needed
4/2–4Build/operation described as low-skill or basic assembly.
Facilities needed
3/2–4Equipment requirements not explicit; assigned moderate default.
Documentation
4/2–5Open resources include several build or operation artifacts.
Validation effort
3/2–47,446 colonies over 44 plates, two species and three screening modes (73.4% accuracy, 92% sensitivity) with an extensive limitations section, but the commercial comparison is cited specs only.
Cycle time
3/1–4240-250 colonies/h described as similar to medium-throughput commercial pickers though far below 1,500-3,000/h; manual picking was never timed.
2 further criteria are recorded but not shown
- Application Level — scored 4 (75% of records share one value), so it cannot separate one build from another.
- Build Time (scored for only 6 of 60 records), so it cannot separate one build from another.
Both remain in the published dataset.
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Matched by doi · retrieved 2026-07-21
Abstract
The optimization of genetically engineered biological constructs is a key step to deliver high-impact biotechnological applications. The use of high-throughput DNA assembly methods allows the construction of enough genotypic variants to successfully cover the target design space. This, however, entails extra workload for researchers during the screening stage of candidate variants. Despite the existence of commercial colony pickers, their high price excludes small research laboratories and budget-adjusted institutions from accessing such extensive screening capability. In this work we present COPICK, a technical solution to automatize colony picking in an open-source liquid handler Opentrons OT-2. COPICK relies on a mounted camera to capture images of regular Petri dishes and detect microbial colonies for automated screening. COPICK’s software can then automatically select the best colonies according to different criteria (size, color and fluorescence) and execute a protocol to pick them for further analysis. Benchmark tests performed for E. coli and P. putida colonies delivers a raw picking performance over pickable colonies of 82% with an accuracy of 73.4% at an estimated rate of 240 colonies/h. These results validate the utility of COPICK, and highlight the importance of ongoing technical improvements in open-source laboratory equipment to support smaller research teams.
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