Transcript Slide 36

Thermal Inkjet Dispense for Pharmaceutical
Research
Lindsey Rucker, Hugh Hobbs, Ahson Saeed
School of Chemical, Biological, and Environmental Engineering
Traditional
Method
1.2
1.2
1
1
JPD
0.6
JWD
0.4
0.2
0.2
0
0
Thermal Inkjet and Titration Tool
10
20
30
40
50
JWD
0.6
0.4
0
JPD
0.8
0.8
Counts( 1E6)
Drug discovery involves a titration process in which
the effects of different concentrations of potential
drug compounds are analyzed. Current methods of
analysis involve steps which are labor intensive, error
prone and, more importantly time consuming.
Results
Counts( 1E6)
Problem
60
0
20
Time (s)
40
Time(s)
A
HP Direct Titration Method
•Simplifies drug titration method
•Leads to reduced labor costs
•Reduction in time
In
essence
thermal
inkjet
technology consists of a resister
and a fluid reservoir. The resister is
positioned directly under (above)
the filling reservoir. The resistor
rapidly heats the fluid forming a
bubble which pushes a drop of ink
out of the nozzle.
•Two jittering methods were tested for mixing
results: Jitter- while- dispense (JWD) and Jitterpost- dispense (JPD).
16 of the nozzles depicted at
the left are present on the
printer heat used in the
instrument.
•JPD has been determined to be the optimal
mixing method for both large and small dispense
volumes, based on the slopes in the data plotted
above.
•Plot A displays results for 50 nL dispense volume,
and plot B displays results for 200 nL dispense
volumes.
Improvements Over the Old Method
Proposal
Traditional
Method
HP Method
2.4
Is Mixing Achievable?
 aL
Bo 

No Jitter
A significant change in counts is caused by the solution not
being fully mixed. Once the fluorescence signal, or counts,
reaches a steady level, the conclusion can be made that
mixing has occurred. This has been determined to be the
best method to quantify mixing using kinetic data.
1 minute
after
dispense
No Cell Death
Jitter
Counts( 1E6)
Immediately 5 seconds
after
after
dispense
dispense
Quantitative Method
1.2
1
0.8
0.6
0.4
0.2
0
Standard
water cup
96 well
plate
0
Immediately after dispense
Vessel
20
40
Time (s)
60
384 well
plate
Bond
Radius
Number
45
mm
3.5
mm
Theoretically
Mix
0.07
2
1.8
1.6
0.06
0.04
0.05
0.03
1 nL FB 2mm
1 nL FB 0.5 mm
1 nL FBLR 1.5 mm
0.02
0.01
1
0
0
20 Time (s) 40
60
20
40
Time (s)
•The team recommends to use JPD in the FBLR
direction for larger dispense volumes. JPD is also
the optimal mixing method for small volumes,
however, stage direction requires further testing.
•It is recommended to further investigate the
jitter time and amplitude for both large and
small dispense volumes.
1000
270
1.7
Yes
Yes
Acknowledgements
800
600
400
200
1.9
mm
1 uL FBLR 1.5 mm
0
1200
Bond Number
•DMSO penetrating in single point
•Cell death caused by high concentration at points of
penetration.
0.08
1.2
r=fluid density
α = acceleration due to gravity
L = radius of capillary tube
g= surface tension of the
interface
2
1 uL FB 0.5 mm
1.4
Bond Number: A ratio of the body forces to the
surface tension forces. A bond number less than 1
indicates that the surface tension forces are
dominating the body forces.
“Jittering”: oscillation of the well plate using the
stage to induce shear between the deposited fluid,
and fluid already in well. The stage can oscillate in the
front to back direction (FB) or dual axis (FBLR).
Cell death
Counts (1E6)
Jittering Method
Challenge: Why Mixing Is
Necessary
2.2
Qualitative Method
0.09
1 uL FB 2mm
Counts(
HP applies their thermal inkjet printing technology
to simplify the drug titration method. One HP
consumable print head is loaded, which is capable
of dispensing over a range of 15 pL to 1 µL. This
leads to reduced labor costs and time requirements,
and increased precision.
Hewlett Packard Titration Tool and Print Head
B
1E6)
Solution
Thermal Inkjet Technology
60
0.5
No
0
0
0.02
0.04
0.06
Radius (m)
0.08
The Engineering Team would like to thank:
• Hewlett Packard
• Kenneth Ward
•Heather Paris
• Ken Duda
• Michael J Day
• Philip H Harding
60