When the fingers close around a covered microplate, are they holding the plate body or only its lid? That distinction determines how the loaded plate is supported when it leaves the source nest. A lid that overlaps the plate wall can occupy the very surface used by an uncovered-plate grip.
For your tooling review, we would start with the plate, lid, contents and source fixture as one handled configuration. The useful drawing shows both the contact surface and the route into it: a suitable plate wall is of little use if the nest blocks the fingers from reaching it.
Define the handled configuration first
The plate and lid part numbers, revisions and loaded mass define the combination under review. A loose lid resting on the plate is different from a mechanically retained cover: contact with the lid alone may lift the lid while leaving the plate behind. Before choosing a gripping height, the load path has to be clear from the loaded plate into the fingers or carrier. Your team defines the sample, process, cleanliness and safety conditions; we use those inputs to review the agreed hardware and interfaces.
Consider a hypothetical plate with a loose lid that overlaps its upper sidewall. A lower exposed wall may offer a gripping surface, but only if the fingers can enter below the lid without colliding with the source nest. Where that access is unavailable, a carrier or a different nest arrangement may be worth evaluating. A carrier adds its own mass, height and locating surfaces, so the receiving station must accommodate the combined assembly. Removing the lid is a separate process decision for your team, not an assumed workaround.
The ANSI/SLAS microplate standards distinguish footprint, height and flange dimensions. Those references help interpret a plate drawing; for this covered assembly, the review also needs the actual lid overlap, allowed contact zones and dimensional variation. Nominal outside dimensions alone do not describe the available finger clearance.
Check the complete pickup and release path
At the source, the relevant clearance is the space left after the plate, lid and nest are all in position. During approach and lift, the fingers must stay clear of neighbouring labware, the fixture and any surface designated as no-contact. During placement, the receiving nest must support the plate before the fingers release it. The fingers then need an exit path that does not catch the lid edge or drag the plate out of its seated position.
A friction grip on a permitted plate wall and support beneath a permitted feature have different constraints. With a friction grip, retention depends on the contact conditions and applied grip force; increasing force can also deform the plate. Support beneath a feature changes the load path but needs room for that support to enter and withdraw. Neither choice can be settled by external width alone. We would propose checking the selected contact geometry with representative loaded samples, the intended orientation and the agreed movement conditions before releasing the setup.
Object presence, lid position, grip condition and final seating are separate questions. A finger-position signal may describe the gripper opening without distinguishing a correctly held plate from contact with the lid. Where sensing is included, its physical detection target and the condition it can actually distinguish should be recorded. The customer’s scheduler uses the agreed interface evidence to decide the next process step; a generic “grip closed” state should not be used as a substitute for missing seating evidence.
The instrument-access review captures the openings and withdrawal space at each station. The positioning error-budget note separates the references and variations that consume that space, including the plate’s location in its nest and the tool’s approach position.
Covered microplate gripping checklist
| Review item | Project entry or evidence | Decision to close |
|---|---|---|
| Configuration identity | Plate, lid and carrier supplier/part/revision | Which combinations are permitted? |
| Loaded condition | Total mass, contents described at an agreed level and known load distribution | Which loaded states require verification? |
| Lid condition | Loose, located, retained or otherwise constrained | May the lid be contacted or carry load? |
| Orientation | Approved pickup, travel and placement orientation | Which rotations or tilts are prohibited? |
| Permitted contact | Plate, lid, carrier or dedicated feature | Which surfaces can the fingers touch? |
| Restricted contact | Labels, seals, optical areas, lid edge or process-defined zones | What must remain clear? |
| Geometry and datum | Dimensions, tolerances and physical reference surfaces | What establishes finger position? |
| Source fixture | Support, nesting, neighbouring items and finger access | Can the approved surface be reached? |
| Receiving station | Opening, approach, final seating and withdrawal space | Can the plate be released without interference? |
| Gripper setup | Tool and finger identity, revision and mounting reference | Which setup applies to this configuration? |
| Sensing | Object, grip, release and identity indications, where in scope | What evidence allows the next state? |
| Verification | Test setup, samples, acceptance criteria, evidence and unresolved items | Who releases the configuration? |
Make changes visible
A replacement lid may leave the plate footprint unchanged while moving its lower edge into the finger path. A new label can alter the contact surface, and a revised nest can change how the plate sits before pickup. These changes call for a focused review of the affected contact, clearance, sensing and acceptance conditions, rather than treating a similar-looking combination as already released.
Use the labware and gripper interface record to keep the selected plate, lid, tool and station configuration together with its acceptance evidence. For a mobile manipulator platform review, send us the plate-and-lid drawing or part references, the loaded condition and views of both station nests. Those inputs let us examine the contact surface and access route together, before a finger shape is selected.