1. Design Alternatives for Micropatterning of Macromolecules
GROUP 3:
Sailaja Akella
Caroline LaManna
Teresa Mak
Rupinder Singh
Advisor:
Emilia Entcheva

2. Design Project
Design a system that facilitates cell deposition and micropatterning to be used in the creation of cellular and polymer based circuits.
Customer Criteria
Suitable for printing proteins for cell adhesion
Fibronectin
Collagen IV
Collagen I –fluorescence labeled
Laminin
Biocompatible/Sterile
Prints accurate & precise patterns
High resolution
Cost-effective (<$500)
Neural cell patterning1

3. Design Alternatives Choose Best Design!
Each alternative design consists of a Droplet-Depositing-Device (DDD), Substrate-Positioning-Device (SPD), and Solution-Supplying-Device (SSD) that may or may not be the same
X-Y Stepper Board with Stationary Print Head
Modified Thermal Inkjet Printer
Modified Piezoelectric Inkjet Printer
Choose Best Design!

4. Technical Considerations
Resolution- 635 dpi
Diameter of droplet (2R): 20um
Separation of drops (e): 20-25um
Fibronectin Solution
20ug/ml - 50ug/ml concentration in H20
Surface Polymer
Print on cover slides (150um thick)
Hydrophobic
Polystyrene, PDMS, Plastic
Increase cell patterning
PEG, Pluronics, BSA

5. Assessment of Design Alternatives
DDD:
For a resolution of 635 dpi, it is necessary to minimize the printed droplet diameter
Velocity of Droplet (Ejection Frequency)
Surface tension and viscosity of solution
Clogging should be prevented
Prevent ink spray phenomenon
SPD:
Movement of substrate should be minimized for high resolution
System should allow for uniquely dimensioned substrates to printed on
SSD:
Could make system robust for different viscosities and surface tensions
Different static pressures
Software handling for all three should be feasible

6. Solution-Supplying-Device (SSD)
Ink Cartridge
Can’t control pressure where the ink leaves cartridge
It is difficult to decontaminate printer cartridge
Difficult to prevent protein loss in the porous membrane of an ink cartridge (clogging)
Height Controlled Reservoir
Variation in potential energy will yield different pressures
Easily decontaminated
Clogging is not an issue
Syringe Pump
Could be used to change pressure; because, small displacements yield large pressure changes
Clogging and Contamination can be easily resolved with a syringe pump

7. Syringe Pump

8. X-Y Printing System Automated X-Y stepper board (SPD)
Stepper motor
Stationary print head (DDD)
Piezoelectric
Software is available
System that uses stationary piezoelectric print head to deposit solution onto motorized X-Y stage1

9. X-Y Printing System Piezoelectric head (DDD): MicroFab:
Printed droplet diameter is 65um (MIT1)
Separation of droplets is 10um
Maximum Resolution
is 339dpi
Cost is $500
Can increase resolution by coupling the ejection of the droplets with the movement of the board
Piezo drop-on-demand print head1

10. X-Y Printing System X-Y Movement (SPD)
Movement of X-Y stage relative to droplet velocity

11. X-Y Printing System Model Price Resolution Speed $750 >1350 0.5 μm
AB Tech
Mini X-Y Linear Motor Positioning Stage
0.5 μm
100+ mm/s
Newmark Systems inc.
NLS4 Series
>1350
0.3 μm
12.5mm/s
Rockwell Automation
0.1 μm
4mm/s
Arrick Robotics XY-9
$750
.005" per .9 degree step
0.15m/s

12. X-Y Printing System Advantages Disadvantages
Substrate-Dimension-Freedom
Software-Ready
Viscosities and surface tensions can be varied
Disadvantages
Costly
Low Resolution (339dpi)
Time consuming to couple the x-y board with the printer head
Slow (5min/coverslip)

13. Thermal Inkjet Printers
Hewlett-Packard Model 550C
Print head (DDD)
Thermal characteristics
Boland et al.2
Printed droplet diameter 2um
Separation of droplets is .25mm
Maximum Resolution is 100dpi
Software Capabilities
Printer head element may only change the ejection frequency
Droplet size can not be changed
Voltage through resistor is constant
HP 550C3

14. Thermal Inkjet Printers
Can’t change the size of the droplet since pressure in channel or the voltage applied to the resistor is predetermined for the particular ink solution
The water-based ink becomes superheated (far above its normal boiling point) and finally reaches the critical temperature for bubble nucleation at around 280 °C. At this point no further heat is applied to the bubble
Vapor bubble expands until all of the heat stored in excess to the boiling point is used to convert liquid to vapor. Once the excess heat is removed, the bubble collapses on to the resistor, which is no longer being heated.
The bubble expansion and formation sequence occurs in 10us. Then there must be a minimum dwell time of us to enable the channel to be refilled through capillary action
Maximum ejection frequency is 50kHz

15. Modified Thermal Inkjet Printer
Caddy System (SPD)
Re-design paper feed mechanism of HP printer
To allow 1mm+ thick material to be inserted without rolling
Involves re-directing feed and increasing height of rollers
Resolution may decrease
Printer with modified paper feed system4

16. Modified Thermal Inkjet Printer
Advantages
Larger nozzle diameter
Mammalian Cells (100um)
Fast (50,000 dots/min)
Disadvantages
Thermal stress on biological materials
Poor resolution (100dpi)
Need to design a caddy system
Can’t control droplet size

17. Piezoelectric Inkjet Printer
Epson® Stylus R200
Print head (DDD)
Built-in Caddy System (SPD)
Necessary to print on our substrate
Resolution of 5760x1440 dpi
Maximum Diameter of Droplet (4.5um)
Diameter of droplet based on experiments
Microencapsulation group achieved a resolution of 254dpi (diameter of droplet 100um)
Software
Use default
Modify voltage supply to actuator
Cost
$99
Epson Stylus R2005

18. Modified Piezoelectric Printer
The size of the droplets is defined by the voltage applied to the deflection plate, the pulse duration, and the diameter of the orifice6

19. Modified Piezoelectric Printer
Advantages
Caddy-ready system
High resolution
Greater than 1200dpi7
Can vary pressure in channel
Might be necessary for solutions of different viscosities and surface tensions
Disadvantages
Difficult to modify software
EPROM based Microprocessor to work in conjunction with different power supply settings

20. Ink Solution How do we increase the resolution?
Current inks have a surface tension of 33.5 dyn/cm (0.0335N/m) and a viscosity of 7.4 cP at 20 ◦C
The surface tension of water (73 dyne/cm) would increase the force required to deform droplet
Leading to an increase in resolution
Viscosity of water (0.89cp) would decrease the time required to wet the surface
Leading to a decrease in resolution

21. Experimental Protocol
Hypothesis:
By increasing the concentration of proteins in our solution, the viscosity of our ink will increase; hence, we will achieve higher resolution
By increasing the surface tension, we will prevent wetting of our substrate
A high surface tension means low attraction and a low surface tension means a high degree of attraction
Image printed solution of fluorescent collagen (type I)
fluorescence microscopy

22. Best Design Solution Modified Piezoelectric Printer
Droplet-Depositing-Device (DDD)
High Resolution (5760x1440dpi)  Droplet Size,Frequency
Substrate-Positioning-Device (SPD)
Built in Caddy System
Solution-Supplying-Device (SSD)
Syringe Pump
Software
Easily Modified
Versatile and Flexible cell patterning
Epson Stylus R2005

23. Best Design Solution Modified Piezoelectric Printer
QFD Analysis
Print Head (121.5)
Easily Modified
Resolution
Droplet Size
Frequency
Low Cost (105)
Print Head
Movement System

24. References
Sanjana NE, et.al. A fast flexible ink-jet method for patterning dissociated neurons in culture. J Neurosci Meth (2004); 136:
Boland T, et al. Cell and organ printing 1: protein and cell printers. Anat Rec A Discov Mol Cell Evol Biol Jun;272(2):491-6.
“HP 550C.” PC Universe (2005). < 16 Nov
“An idiot's guide to making a CD printer from an Epson 640.” VideoHelp.com (2005) < 15 Nov
“Epson Stylus R200.” Epson America, Inc (2005). < 16 Nov
US Patent Office <
Setti L et al., An amperometric glucose biosensor prototype fabricated by thermal ink jet printing. Biosen & Bioelec 20 (2005)