This document explains how Synthace integrates with the Finger Exchange System (FES) on the Tecan Fluent Robotic Gripper Arm (RGA). You will learn how to configure Fluent carriers and worktables to optimise plate movements via the RGA, finger selection, and how plate movement and regripping are handled.
The focus is on:
How Synthace chooses RGA fingers by default
How to control or override this default behaviour
What happens when a plate move requires changing fingers or grip modes
Overview: RGAs and Fingers on the Fluent
Synthace uses the Fluent Robotic Gripper Arm (RGA) primarily for moving plates between deck positions and peripheral devices (e.g., readers, shakers, centrifuges).
An RGA can be configured in one of two ways:
Fixed fingers – permanently mounted
Finger Exchange System (FES) – allows the RGA to dynamically mount and unmount different finger types stored on the worktable
Supported Finger Types
Tecan supports four finger types, all of which are recognised by Synthace:
Centric – grips a plate centrally from the top
Eccentric – grips a plate from the top with an offset
Eccentric Long – similar to Eccentric, with a larger offset
Tube – for handling tubes (not plates)
Note: Only Centric, Eccentric, and Eccentric Long fingers can move microplates. Tube fingers are used exclusively for tubes.
How Synthace Uses Finger Exchange
When an RGA with FES is available, Synthace manages finger mounting automatically:
On the first plate move, Synthace mounts the required fingers
During execution, fingers are exchanged as needed
At the end of the run, fingers are unmounted
This ensures consistent behaviour regardless of the initial state of the instrument
Default Finger Exchange Logic
Synthace automatically determines which finger type should be used for each plate move. This decision is based on the location of the plate, the destination, and the known physical constraints of the Fluent.
By default, Synthace applies the following logic:
Location type | Allowed fingers | Preference |
Main deck grid sites | Centric, Eccentric | Eccentric preferred |
Plate hotels | Eccentric only | — |
Left, right, or rear deck extensions | Eccentric only | — |
Rotanta centrifuge | Centric only | — |
Other peripheral devices (e.g., readers, shakers) | Eccentric only | — |
This behaviour reflects common physical accessibility constraints on the Fluent.
Note: The Rotanta centrifuge is only supported for use with the Filter Plates element set, and is not usable in workflows using the Core Elements or Robocolumns elements.
Example: Default Behaviour
Scenario
A plate is moved:
From a hotel
To a plate reader
Result
Hotel → requires Eccentric
Plate reader → requires Eccentric
Synthace mounts Eccentric fingers once and performs the move directly
No regripping or finger exchange is needed.
Controlling Finger Selection
In some layouts, the default heuristic may be too permissive. Synthace allows you to explicitly control which fingers may be used for a given carrier type.
Using SynthaceRGAFingers
You can define a custom carrier attribute named Synthace RGAFingers . This attribute should be added to the carrier definition as required.
The value is a comma-separated list of allowed finger types, in priority order. The order of the allowed finger types dictates which fingers are used by default. Taking the Centric, Eccentric example above; Synthace will assess whether Centric fingers can be used based on the allowed fingers for the source and destination locations. If centric fingers are not compatible, then the use of Eccentric fingers will be assessed. If neither finger type can be used for a movement, the Synthace will automatically break the movement down into two stages, using the regrip location, in combination with a mid-movement finger exchange.
Attribute value | Meaning |
| Both allowed, Centric preferred |
| Only Eccentric allowed |
| Only Eccentric Long allowed |
empty value - | Plate moves to/from this carrier are prohibited |
When Should You Override the Default?
Common reasons include:
Plate nests at the very back or front of the deck, which may only be reachable with Eccentric fingers
Sites that are physically inaccessible with a finger type, i.e., due to nearby tall carriers or geometric constraints of the device
Preventing plate moves entirely to or from a carrier
How Grip Modes Affect Plate Moves
Fluent supports four grip modes:
N – Narrow (right side)
NR – Narrow Reverse (left side)
W – Wide (front)
WR – Wide Reverse (back)
Each site defines which grip modes are allowed, and Fluent automatically chooses the first grip mode that works for both the origin and destination.
Synthace does not explicitly set the grip mode. It is inferred by Fluent based on the allowed grip type configuration of the source and destination sites.
If no compatible grip mode exists, a direct move is impossible.
Regripping and Finger Changes
Sometimes a plate cannot be moved directly from A → B. Synthace handles this by performing a regrip:
A → R → B, where R is a regrip station.
Why Regripping Happens
There are two main reasons:
Grip mode incompatibility
Example: Hotel (N only) → rear deck nest (W only)
Finger incompatibility
Example: Hotel (Eccentric) → centrifuge (Centric)
Synthace Regripping Behaviour
When required, Synthace plans regrips explicitly. The regrip will be shown in the simulation preview as two independent plate moves. Standard Fluent regrip stations (7mm Regrip Nest, 61mm Regrip Nest) are used for the regrips.
Note: The Regrip nests must have all grip types enabled in Fluent Control.
Example: Finger-Driven Regrip
Scenario
Plate starts in a hotel (Eccentric required)
Destination is a centrifuge (Centric required)
Result
Hotel → Regrip Nest (Eccentric fingers)
Finger exchange (Eccentric → Centric)
Regrip Nest → Centrifuge (Centric fingers)
Summary
Synthace automatically manages RGA finger mounting and exchange on the Fluent
A clear default heuristic determines finger choice based on the location of the source and destination locations associated with a plate movement.
You can override finger selection using the
SynthaceRGAFingerscarrier attributeWhen direct moves are impossible, Synthace plans explicit regrips