Single Steps, Power Steps, and Smart Steps: Choosing the Right Tool for the Job

Venus has three levels of pipetting step

When you open the Venus toolbox, you'll find three categories of instrument-specific steps for the Hamilton STAR: Single Steps, Power Steps, and Smart Steps. They all produce pipetting behaviour. They have different levels of control, different numbers of parameters, and different appropriate use cases.

The common mistake is defaulting to Smart Steps because they look simplest, or to Single Steps because they seem most complete. The right choice depends on what the step needs to do, and understanding the trade-offs at each level is the difference between a method that's easy to maintain and one that's brittle and hard to debug.

The three tiers

Smart Steps: highest level, least control

Smart Steps are pre-built workflow steps that handle complete operations, tip pickup, aspiration, dispensing, and tip eject, in a single configured step. Examples:

• 1000ul Channel Pipette -- Simple (1-1): transfers from one sequence position to one destination position
• 1000ul Channel Pipette -- Replica (1-n): distributes from one source to multiple destinations
• 1000ul Channel Pipette -- Pooling (n-1): pools from multiple sources into one destination
• 1000ul Channel Pipette -- Aliquot: aspirates a bulk volume and dispenses it in multiple equal aliquots

Smart Steps also include the deck management steps: Load, Load and Match, and Unload for Autoload carrier management.

What Smart Steps handle for you: tip pickup, tip eject, sequence advancement, LLD configuration (simplified), and basic error handling, all without requiring separate steps for each action.

What Smart Steps don't give you: fine-grained control over LLD sensitivity, mix cycles at specific depths, per-channel volume differences, multi-phase aspiration, different liquid classes for aspirate vs dispense, or any non-standard transfer pattern.

Best use cases: straightforward reagent distribution, simple sample transfer in standard plate-to-plate formats, and rapid method prototyping where the priority is getting a working draft quickly. Smart Steps are also appropriate for operators who will run a validated method but don't need to understand or adjust the underlying pipetting parameters.

When Smart Steps are the wrong choice: any workflow where you need LLD control beyond on/off, where aspirate and dispense liquid classes should differ, where mix cycles need to be at a specific depth, or where the transfer logic is more complex than a standard 1-1, 1-n, n-1, or aliquot pattern.

Power Steps: middle tier, composite operations

Power Steps combine tip pickup, aspiration, and dispensing into a composite step but expose more configuration options than Smart Steps. They're designed for frequently used operations that need more control than a Smart Step but don't require the granularity of individual Single Steps.

Available Power Steps include:

• 1000ul Channel Aspirate (Power Step): aspirate with configurable LLD, volume, and liquid class
• 1000ul Channel Dispense (Power Step): dispense with configurable LLD, volume, and liquid class
• CO-RE 96 Head Aspirate / Dispense (Power Steps): full-plate 96-head operations in a single step
• iSWAP Transport (Power Step): pick up plate, move, and place in one step
• 1000ul Channel CO-RE Grip Transport (Power Step): channel-based plate transport

Power Steps for aspiration and dispensing still require separate Tip Pick Up and Tip Eject Single Steps to complete a full transfer cycle. They handle the fluid movement but not the tip management.

Best use cases: workflows where you need control over LLD settings or liquid classes beyond what Smart Steps offer, but where the transfer pattern itself is still standard. The iSWAP Transport Power Step is the preferred choice for plate movement in most workflows because it bundles the Get/Move/Place sequence into one configurable step.

Single Steps: lowest level, maximum control

Single Steps are individual hardware commands. Each one does exactly one thing:

• 1000ul Channel Tip Pick Up: pick up tips
• 1000ul Channel Aspirate: aspirate liquid
• 1000ul Channel Dispense: dispense liquid
• 1000ul Channel Tip Eject: eject tips
• Initialize: home the instrument
• Calibrate Carrier: verify a carrier position
• iSWAP Get Plate: grip a plate
• iSWAP Place Plate: place a plate
• iSWAP Park: stow the iSWAP arm

A complete transfer with Single Steps requires at minimum four separate steps: Tip Pick Up, Aspirate, Dispense, Tip Eject. You construct the full operation from its component parts.

What Single Steps give you that nothing else does:

Full access to every parameter in every tab of every step dialog. For the Aspirate Single Step, this means separate cLLD and pLLD control with individual sensitivity settings, fix height from bottom, submerge depth, max height difference, liquid following during aspirate, pre-rinse mix cycles at a specified depth and volume, Z-move after step, and per-channel volume control. For the Dispense Single Step: the option to specify a different liquid class than was used for aspirate, side touch, post-dispense mix cycles, and physical bottom / max pipetting depth control.

None of these fine-grained parameters are accessible through Smart Steps or Power Steps.

Best use cases for Single Steps:

• Any aspiration requiring specific LLD sensitivity settings
• Aspirations using pLLD (pressure-based LLD for non-conductive liquids, which is only available as a Single Step parameter)
• Transfers where aspirate and dispense should use different liquid classes
• Multi-phase aspirations using 1000ul Channel Aspirate 2nd Phase
• Mix cycles that must occur at a specific depth before or after aspiration
• Methods requiring dispense on the fly (1000ul Channel Dispense on the Fly)
• Any iSWAP operation requiring fine-grained grip force, tolerance, grip type, or collision control
• Any CO-RE Grip operation

Liquid classes: the parameter underneath the step

Regardless of which step tier you use, every aspiration and dispense references a liquid class. The liquid class is the set of physical pipetting parameters that determines how liquid actually moves: flow rates, blowout volume, transport air, retract distance, over-aspirate volume, settling time, and pre-wet cycles.

Key liquid class parameters and what they control:

Venus ships with default liquid classes for standard aqueous solutions, DMSO, glycerol, organic solvents, and other common reagents. These defaults are a starting point, not a guarantee. If your assay uses a reagent with unusual viscosity, surface tension, or volatility, the default liquid class may produce inaccurate volumes — the same caution applies to dead volume calculations, which assume a correctly calibrated liquid class.

Liquid class selection in step dialogs: in Smart Steps, liquid class is selected from a dropdown filtered by tip type. In Single Steps, the Basic tab provides Tip type and Dispense mode dropdowns that together filter the available liquid classes. This is why tip type matters in the labware definition: the tip type of the tip rack definition determines which liquid classes Venus will show as available.

A different liquid class for dispense: one of the most useful Single Step capabilities that Smart Steps can't provide is specifying a different liquid class for the dispense phase than was used for aspirate. This applies to workflows where you aspirate a non-standard reagent but dispense into a standard aqueous destination, or where the surface tension and droplet behaviour at the dispense target requires different flow rate settings.

Dispense modes

The Dispense mode parameter filters available liquid classes and affects physical dispense behaviour:

In Smart Steps, the dispense mode is preset. In Single Steps and Power Steps, you select it, and this selection filters the liquid class list.

The channel pattern: controlling which channels are active

Every pipetting step includes a channel pattern parameter, the 8-character string of 1s and 0s that specifies which of the 8 channels participate in the operation. 11111111 = all 8 channels; 10000000 = channel 1 only.

The channel pattern can be:

• Hard-coded as a string in the step dialog (e.g., 11111111 for all 8 channels)
• Set via tickboxes in the step dialog
• Passed as a variable, where a string variable calculated earlier in the method logic is passed into the channel pattern field

The variable channel pattern is one of the most powerful non-obvious features in Venus. It allows a single aspirate step to be reused across multiple loop iterations with a different subset of channels active on each pass. This is covered in the variables and loops article, but the key point is: don't hard-code the channel pattern if the number of active channels will vary across runs.

Choosing the right tier: a decision guide

Don't skip TADM

One Single Step that's often overlooked: Wait for TADM Upload. TADM (Total Aspiration and Dispense Monitoring) records pressure traces for every aspiration and dispense, checking them against tolerance bands to detect blocked tips, empty vessels, or short aspirations.

If your method uses TADM monitoring and includes downstream steps that depend on TADM results, for example branching logic based on whether a step passed TADM, the method must include a Wait for TADM Upload step after the monitored pipetting step. Without it, the TADM data may not be available in the database by the time the downstream logic tries to read it.

TADM is one of the most effective quality control tools available in Venus and costs nothing in reagent to use. Enable it for any method where pipetting failures should be detected rather than silently propagated into assay results. TADM and error handling more broadly are covered in the final article in this series.

With step types and liquid classes covered, the next article shows how to make methods adapt at runtime: variables, calculations, and loops.