Transcript SPIE lezing - PicoFill Systems

PicoFill-Systems
Outlicensing Electrospray Deposition onto Small Targets
Technology Platform Requirements:

High Voltage power supply (2 kV) to induce an electric field between a capillary-outlet and a
substrate.

Liquid flow through a capillary induced by a pump or induced by pressure (preferably stable liquid
flow for precision spraying). The Harvard 2000 allows liquid flows down to a few picoliters/second.

Computer controlled x-y-(z) stage (preferably high speed- and micrometer-precision actuators).
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Microscope–CCDcamera set-up to visualize and verify proper spraying.
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Low–high conductive surfaces: silicon nitride, metal, metal coated plastics (10 nm thick metal layer)
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Liquid surface tension < 0.05 N/m: pure water requires addition of > 0.1% of the surfactant Brij 35.
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Capillary material: any low–high conductive material.
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Spraying Set-Up Example: assembled devices
Syringe-capillary
Harvard Pump
High Precision
Microscope,
CCD-camera
Computer controlled
Motion controller:
Sends x-y-z data to
the x-y-z table
Syringe-capillary
Power Supply
x-y-z stage
MicroArray
Upon execution of the desired x-y-z data, a substrate is moved underneath a
capillary at high precision while liquid is sprayed onto the substrate at controlled
flow rates of picoliters–nanoliters per second.
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Spraying of Arrays of Dots
A. Piston pushes liquid
through syringe while
electric field is applied
B. Slide is moved
downward to lower the
electric field: spraying stops
1–2 kV
Spray of
droplets
MicroArray or
slide
C. Slide is moved upward
and spraying resumes
1-2 kV
1-2 kV
Spot
Slide is moved downward
and sideways: typical
200 – 1000 micron
Second spot is
sprayed onto slide
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Spraying Parameters
Dot Size
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Dot size is related to the distance between the capillary-tip and the substrate (spraying distance)
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Dot size is related to the capillary outer diameter: the smaller the outer diameter, the smaller the cone
size
•
Dot size is related to the flow rate: at low flow rates the liquid evaporates rapidly resulting in a solid dot
instead of a donut like dot.
•
Typical dot sizes for a capillary-OD of 150 micron and flow rates of 100–400 picoliter/second :
150–400 microns at spraying distances of 250–500 micron, respectively
MicroArray Applications
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Flow rates: picoliters-nanoliters/second
•
Distance between capillary-tip and substrate (spraying distance): 200–500 micron
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Dot size microarray: 100–400 micron at spraying distances of 200–500 micron
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Preferred capillary outer diameter: 50–200 micron
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Maximum speed of x-y-z table depends on actuators: 1.6 inch/sec (4 cm/s) for high speed actuators
Dotting of fractions onto MALDI plate targets
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Flow rates: 1 nanoliter/second – 0.6 microliter/second
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Dot sizes: 400–1500 micron at spraying distances of 500–2000 micron, respectively
•
Silicon- or Peek capillary outer diameters: 100–360 micron
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