Contact-Free Liquid Dispensing vs. Touch-Off Dispensing
Touch-off and contact-free dispensing answer the same basic need—deliver the intended sample—but they manage the liquid remaining at the pipette tip in different ways. Understanding that difference helps laboratories choose an appropriate workflow.
Touch-off and contact-free dispensing answer the same basic need—deliver the intended sample—but they manage the liquid remaining at the pipette tip in different ways. Understanding that difference helps laboratories choose an appropriate workflow.
What touch-off means
In touch-off dispensing the tip touches a destination wall or liquid surface to detach a hanging droplet. Operators may use a controlled touch-and-drag motion. This familiar method can work well when contact is acceptable, although placement and movement can influence transfer consistency.
How contact-free release works
Contact-free dispensing releases liquid without requiring contact between the tip and destination. A sufficiently controlled flow or ejection movement must overcome the liquid’s tendency to remain on the tip. DRD’s Differential Displacement approach separates precise aspiration from a higher-flow dispensing behavior intended for this purpose.
Where the distinction matters
Non-contact transfer may be valuable for dense microplates, sterile environments and processes where touching a surface increases carryover concerns. It can also simplify automated motion by reducing dependence on a carefully choreographed touch-off sequence. However, excessive velocity may cause splashing or aerosols, so the delivery setting matters.
Making a fair comparison
Run equal-volume transfers with the same liquid, tip and receiving vessel. Measure delivered volume, repeatability, residual liquid, cross-well carryover and splash. Evaluate both methods at the lowest target volume, not just at an easy midrange setting.
For a system-level decision, compare these principles against the performance data and technical documentation supplied for the particular DRD product. See the related DRD product and discuss the intended application with the engineering team.
Related technical resources
Explore the relevant DRD product and technical description, or review the Applications & Science page for demonstrations and background. Product-specific claims should be checked against current test documentation and operating conditions.
Frequently asked questions
Is contact-free dispensing the same as aerosol-free dispensing?
No. Contact-free describes the absence of physical touch; aerosol formation must be separately evaluated.
Can touch-off be appropriate?
Yes. It remains useful for many routine workflows when contact with the receiving surface is acceptable.
Does higher flow always improve results?
No. The correct release behavior balances complete delivery with gentle handling of the sample and destination.