PicoFill-Systems Outlicensing Electrospray Deposition onto Small Targets

1. Dot 0.4 millimeter PicoFill-SystemsOutlicensing Electrospray Deposition onto Small Targets • Target Applications: • MicroArray Applications: spraying of enzymes, metabolites, co-factors, yeast cells, antibodies: addition of up to 20 wt% of carbohydrates like trehalose to fully preserve enzyme activities after spraying followed by storage. Activities of enzymes, metabolites and cofactors are not reduced by the electric field. • Dotting of Microliter & Nanoliter Fractions onto MALDI targets • Coating Industry: spraying of liquids containing particles, polymer, etching or curing agents, etc. Spraying of viscous materials can be achieved at high temperature.

2. Special Features • The charged droplets are pulled to the grounded substrate on-the-flight, so, no contamination of adjacent targets. • The sprayed amounts of liquid is controlled and flexible by varying the spraying time and/or flow rate. Dot-size is varied by adjusting the spray-distance. • The uniform charged droplets repel each other on-the-flight resulting in a layer of droplets instead of a droplet. This eliminates the donut effect (coffee stain effect). • The droplet spray is always directed toward grounded elements, meaning that if grounded conductive targets are embedded within non-conductive material, the droplets will only fly to these conductive targets like metal wiring or pins. • Capillaries are bendable, low-cost and may be 50 micron in outer diameter, allowing spraying of spots or lines at widths in the order of 10–100 micron. • Parallel spraying was achieved with three capillaries (outer diameter of 150 micron) that were placed 600 micron apart.

3. Spraying Parameters Dot Size • Dot size is related to the distance between the capillary-tip and the substrate (spraying distance) • 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 • Flow rates: picoliters-nanoliters/second • Distance between capillary-tip and substrate (spraying distance): 200–500 micron • Dot size microarray: 100–400 micron at spraying distances of 200–500 micron • Preferred capillary outer diameter: 50–200 micron • 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 • Flow rates: 1 nanoliter/second – 0.6 microliter/second • Dot sizes: 400–1500 micron at spraying distances of 500–2000 micron, respectively

4. Spraying of Arrays of Dots A. Piston pushes liquid through syringe while electric field is applied C. Slide is moved upward and spraying resumes B. Slide is moved downward to lower the electric field: spraying stops 1-2 kV 1–2 kV 1-2 kV Spray of droplets Second spot is sprayed onto slide MicroArray or slide Spot Slide is moved downward and sideways: typical 200 – 1000 micron

5. Parallel Spraying Spots: 0.6 millimeter apart