Virginia Commonwealth University
VCU Scholars Compass
Capstone Design Expo Posters
School of Engineering
2016
Development of a Tabletop Soft Gel Encapsulation
Machine
Amanda Carter
Virginia Commonwealth University
Lara Hamid
Virginia Commonwealth University
Harini Muralikrishnan
Virginia Commonwealth University
Bethlehem Solomon
Virginia Commonwealth University
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Team Members: Amanda Carter, Lara
Hamid, Harini Muralikrishnan, Bethlehem
Solomon
Faculty Advisor: Christina Tang Ph.D.
Sponsor: Pfizer Consumer Healthcare
Development of a Tabletop
Soft Gel Encapsulation Machine
Sponsor Advisor: Mallik Karamsetty Ph.D.,
Jeffery Holbrook, John Bachert III Ph.D.
Soft Gelatin Capsules:
• Made with gelatin, water, plasticizer and filled with
medicine
• More flexible and easier to swallow than a tablet
• Can encapsulate sensitive materials: liquids, semiliquids, pastes
• Minimize risk of tampering
Existing Design
Current commercial
scale machine:
• Produces thousands of
capsules in 2-3 hours
• Minimum batch size
required: 25 kg gel melt
• Spreader boxes: holds
and dispenses molten
gelatin
• Die Rolls: punch out
capsules from gelatin
ribbons
• Injection Wedge:
heated wedge near die
rolls to facilitate capsule
sealing
Aims
• Main objective: to produce hundreds of soft gel capsules to use
for running samples and trials
• Purpose: to enable rapid changeover and an ability to make a
smaller number of capsules for research and development
purposes
• Idea: to dispense molten gelatin, form gelatin ribbons, inject
medicine, and seal capsules
Design
Idealized Image of Design
Syringe Heaters and
Pumps: pump molten
gelatin onto conveyor belts
Luer-Lok
tubing
Programmable Syringe Pump:
injects medicine into capsules
as they are being made
Conveyor Belts: cool
gelatin, form ribbons, and
transfer them to die rolls
Contact Time Calculation:
• Amount of time required to cool a one foot gelatin strip from 60ºC to 35ºC
• Equation comes from a calculation of lumped capacitance method –
assumes uniform temperature distribution throughout the process
• Bi<0.1 for this process; therefore, lumped capacitance approximation
is valid
𝜌𝐶𝑝 𝑉
𝑇∞ − 𝑇0
𝑡=
∗ 𝑙𝑛
= ~3 𝑚𝑖𝑛𝑢𝑡𝑒𝑠
ℎ𝐴𝑠
𝑇∞ − 𝑇
ℎ∗𝐿
𝐵𝑖 =
= 0.0104 < 0.1
2𝑘
Die Rolls: temperature
controlled; punch out
capsules (7.5 rpm)
Additional cooling is not required
Results
Description
Desired Values
Actual Values
Width of ribbon
5.00 cm (min)
Variable
Thickness of ribbon
0.01-0.05 in
0.02-0.03 in
Temperature of die rolls
-
43-45C
Temperature of molten gelatin
(syringe heaters)
57C -62C
60C
Flow rate of
molten gelatin
108.38
cm3/min
25
cm3/min
(max)
Flow rate of injection fill
60.94 mL/min
25 mL/min (max)
Injected Volume
Variable
0.203 mL 0.06%
Downtime of Injection
1.2 seconds
0.9 seconds (max)
Injection System Flow Rate versus Time
Die rolls:
RPM: 7.5 rpm
Linear Velocity: 294.1
cm/min
0.250
Flow Rate (mL/sec)
Background
0.200
Capsules:
Length between
capsules: 2.413 cm
Time of capsule
formation: 0.0082 min
0.150
0.100
0.050
0.000
0
1
2
3
4
5
6
7
Time (sec)
8
9
The programmable
syringe pump was used
to synchronize capsule
formation and injection of
model fluid
Gelatin ribbons of variable thickness can be made from molten gelatin
Future Plans
Conclusions
• The injection of model fluid can be timed with capsule formation
• Can produce ~50 capsules per minute using ~100 g of molten gelatin, which is
significantly lower than the full scale machine
•
•
•
•
Sealing of capsules with heated die rolls
Automating more of the process: movement of gelatin from molten to ribbons to capsules
Transitioning from model fluid to medicine
Reducing the rotations per minute of the die rolls from 7.5 RPM to 3 RPM to allow
sufficient time for sealing and formation of capsules
Acknowledgements: We would like to thank Dr. Christina Tang for
her advice and support throughout the project, and would like to
thank the Pfizer team for their sponsorship and cooperation.