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Hydrodynamic Isolation™
Sample Delivery and Label-free Analysis
After decades of research on label-free biosensors one issue has become crystal clear, the method by which sample is delivered, or addressed, to the sensor surface is critical to the performance of the technology. Sample delivery in label-free analysis determines everything from what parts of the binding events can accurately be monitored to how much sample is needed per test, which in turn defines the ease of use, quality, and applicability of the technology.
Continuous Flow Sample Addressing
The one sample delivery method that has consistently been shown to generate the highest quality data, and to be the most flexible in terms of potential applications when combined with label-free detection, is Continuous Flow sample addressing. In continuous flow addressing, sample solutions are applied to the sensor surface as discrete volumes within a continuously flowing stream of assay buffer.
 Continuous flow sample addressing provides a number of key benefits not possible in static based sample addressing methods, greatly enhancing the performance of label-free analysis.
| Instantaneous transitions between solutions at sensor surface |
Direct, high quality monitoring of all phases of binding
No 'missing data' for low affinity binders |
| Samples in constant motion during analysis |
Efficient transport of molecules to sensor surface enabling accurate kinetic rate determinations |
| Continuous supply of fresh sample to sensor surface during analysis |
No erroneous results due to sample depletion or evaporation |
| Multi-sensor addressing |
In-line control referencing
Multiple analyses with a single sample |
When designed using microfluidic and MEM’s technologies, continuous flow sample addressing possess all the benefits of static sample addressing with none of the problems.
| Capability |
Continuous Flow |
Static |
| High throughput Analysis |
Yes |
Yes |
| Sample recovery |
Yes |
Yes |
| Molecular transport |
Efficient |
Limitied |
| Direct dissociation rate analysis |
Yes |
No |
| Instantaneous solution transitions |
Yes |
No |
| Sample depletion during analysis |
No |
Yes |
| Sample evaporation during analysis |
No |
Yes |
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 Hydrodynamic Isolation™
Hydrodynamic Isolation™ (HI™) is Sierra Sensors proprietary continuous flow, microfluidic sample delivery technology. HI™ combines hydrodynamic focusing with location specific cell evacuation to create a high performance continuous flow sample addressing method that is robust, flexible, and simple to multiplex.
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In HI™ guide streams of buffer solution control the size and location of sample streams passing over the sensor surface. During analysis the sample streams are introduced to, and evacuated from, the flow cell at specific locations relative to the target sensors. The result is the addressing of highly discrete volumes of sample to any sensor location.
Any Sample, Any Sensor, Any Time™
The combination of hydrodynamic focusing and site specific evacuation makes HI™ a very powerful and flexible sample addressing method. HI™ gives user the ability to address Any Sample, to Any Sensor, at Any Time™, in the analysis process.
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