1. Further work is needed to reconfigure the electronic components of the instrument, ensure proper heating in the water
baths, and test the miniature PCR machine. Looking to the future, the next stages of the project focus on deployment and
field testing of the instrument.
Ultra low-cost Fabrication of a 3D-Printed PCR Instrument
Leah Buck 1, Christopher Trippell 2, Matthew M. Champion 3
1 Department of Chemistry and Physics, Saint Mary’s College, lbuck01@saintmarys.edu
2 Marian High School, Mishawaka, IN
3 Department of Chemistry and Biochemistry, University of Notre Dame
Background Commodity Cost Breakdown
Results
References
Acknowledgements
The polymerase chain reaction (PCR) is arguably the most significant advance in molecular biology and the most widely used technique in
the field. It allows for the exponential amplification and copying of nucleic acids, like DNA. This process is essential for genome sequencing,
disease diagnostics, human remains identification, and numerous other direct and indirect scientific applications. There is a fundamental need
to expand access and reach of this technology into environments in which resources are limited, including underfunded STEM educational
programs and low-resource environments where the infrastructure is insufficient to sustain and repair commercial instrumentation.
We seek to design a low-cost approach to doing PCR, and lab instrumentation in general, providing the functionality of commercial
instruments but at approximately 1 % of the retail price of similar instruments. Low-cost instruments often face one or more of the following
problems: high solvent and reagent volumes, low throughput, and/or relatively expensive firmware. We intend to address these in the design
of our low-cost PCR instrument.
Wiecek, A. S. Cheap PCR: new low cost machines challenge traditional designs. BioTechniques 2010.
Wong, G.; Wong, I.’ Chan, K.; Hsieh, Y., Wong, S. A Rapid and Low-Cost PCR Thermal Cycler for Low Resource Settings. PLoS ONE. 2015, 10.
Table 1. Price summary by part of 96-sample and 12-sample PCR machine.
Figure 4. Pie chart of the fabrication cost distribution of
96-sample PCR machine.
Further Work
Fabrication
Problems Solutions
Firmware
• Interface elements (screens, buttons, controllers) in traditional
instruments are costly
• Some low-cost instruments use microcontrollers (Arduino etc.) that
are inexpensive but require infrastructure to code
Firmware
• Use a novel, internet-based firmware
• YouTube sound files control servo motors
Maintenance
• Traditional instruments require expertise to maintain and repair
• Shipping times for replacement parts leaves the instrument unusable
until installation is effected
Maintenance
• Instrument is user-assembled, so user already has much of the
knowledge needed to replace parts
• 3D printing parts on demand eliminates waiting time and shipping
costs
Transport
• Traditional instruments are expensive to ship
• Field researchers must accommodate a back-up plan and
infrastructure
Transport
• Low-cost PCR only requires electronics to be shipped, could even
be purchased and assembled by the user in their location
• 3D printed parts are lightweight and easy to replace, eliminating the
need to have contingencies in the field
Operational Costs
• Conventional PCR instruments have low solvent and reagent
volumes and high throughput, but initial capital needed is prohibitive
to low-resource environments
• Other low-cost instruments require high solvent and reagent volumes
and/or can only process a few samples at once, driving up cost per
sample
Operational Costs
• The low-cost 96 sample PCR instrument has about 50 USD of
materials, making it accessible to resource-limited environments
• Instrument uses same reagent and solvent volumes as commercial
instruments
• 96-sample instrument has throughput similar to that of traditional
models
Figure 2. Side view of 12-sample “miniature” PCR instrument.
Figure 1. Top-down view schematic of low-cost PCR instrument
Design
The design of this instrument uses water baths to provide the thermal
cycling essential to preforming PCR. This technique is executed using
3D printed parts, servo motors, and a modified PC power supply as
configured in Figure 1 at left. The instrument was modified based on
earlier student work.
Both standard 96 sample and personal 12 sample models of the
instrument have been prototyped. The 96 sample model offers high
throughput, while the 12 sample model is less expensive to fabricate,
and has lower input and power costs. The standard model is
designed for laboratory-based research or classroom education, and
the personal model could be used in at-home diagnostic kits or real-
time field work.
CAD/Parts Printer Filament
• Designed in TinkerCad and
OpenSCAD
• All available as STL, some parametric
files
• Electronics wiring, motor, opamp etc.
(Newark)
• Fusion Deposition Modeling (FDM)
style
• ORION Delta™ (SeeMeCNC)
• Chosen for low cost and easy
accessibility
• All parts fabricated in nGen filament
(ColorFabb) or HTPLA (Protopasta)
• Chosen for print quality and robustness
against high temp.
• $0.04 /gram
Part Description
A Water baths set at different temperatures to
denature, anneal, and amplify DNA
B Sample rack, available in 96 or 12 sample models
C Arm that holds and directs sample rack
D Tilt motor moves arm and sample rack up and
down into and out of water baths
E Pan motor moves arm and sample rack left and
right to different water baths
Part Price (96 Sample) Price (12 Sample)
3D Printed Parts $19.70 $2.78
Servo Motors (2) $6.00 $4.00
Heaters $4.80 $2.40
Power Supply $12.00 $12.00
Asstd. Electronics $6.50 $6.50
Hardware $2.00 $2.00
Total $51.00 $29.68