Difference between revisions of "Team:UMaryland/Design"

Revision as of 07:35, 18 September 2015

What is PCR?

Polymerase Chain Reaction or PCR is a common tool used in the field of biology to amplify DNA or RNA. Invented by Dr. Kary Mullis, PCR is conducted trough cycling DNA, primers and polymerase through various temperatures. The reaction is started by heating the reaction mix to 95 degrees Celsius. The high heat overcomes base stacking interactions and hydrogen bonds which maintain the double helix, a process called denaturation. The machine then cools down to an annealing temperature in order for primers, short ssDNA oligos, to recognize selected DNA sequences, form duplex, and allow for polymerase to bind. Annealing is followed by extension, which is performed by the polymerase at its active temperature, typically around 72 degrees. The polymerase forms a daughter strand by adding nucleotides to the primer in the 5'-3' direction. I don't think this is necessary, especially not here. If you want to write how PCR works, put it in description. PCR is also a very complicated process so we'll need to invest a lot of space into it if you want to do it justice

Purpose

Although the process of amplifying ~~genetic material~~ is remarkable, the hardware needed to do it is relatively simple-- all that is required are three different temperatures which are maintained by the machine, enabling the enzymes and template to do the work of PCR. Current PCR machines cost thousands of dollars, and although there exists open source, DIY PCR machines, their costs still range in the hundreds of dollars. Here at the University of Maryland, we thought that that was an absurd notion. PCR, because of its simplicity and utility, is a robust tool for the diagnosis of many diseases both in the developed and developing world. Making the device cheaper would give more people accessibility to this platform. Accessibility enables further innovation and development of novel methods for disease detection and this in turn enables better and faster diagnosis and treatment both in the developed and developing world.
Another major advantage of "cheap" is education. Here at the University of Maryland, we acknowledge that iGEM is a competition, however we also understand that this competition is also a collaboration. It is an opportunity for all of us to learn from one another and serves as the foundation for future discovery, innovation, and new projects. We hope that our work with the PCR machine will inspire many more teams to tackle designing hardware. We hope that our current collaborations with Duke University foster better and more innovative projects from both of our teams. And most important, we hope that our efforts will be able to inspire the future generation of iGEMer's and the newest members of the iGEM community; high school students.
I remember, along with my fellow teammates, learning about PCR by cutting up little paper nucleotides and putting them into a brown bag and then having our hands act as the "polymerase" that would pluck the nucleotides out and match them with the template strand we were given. I remember taking away very little from this "lab" other than a few paper cuts. In subsequent years, I went through a few internship programs where I was able to learn in greater detail the steps of PCR, eventually learning how to design primers, program the machine, and setup my own reactions. However, I believe that if we truly want to bring synthetic biology to the public, we have to allow them the opportunity to actually do PCR, not through a paper bag which is conceptual understanding, but a real reaction where the end products are the real deal, actual amplified DNA. We still have a ways to go... the enzymes have to become cheaper pipettes need to become cheaper, but designing a below 50 dollar PCR machine is the first step in this endeavor.

Alternative Version:

UMaryland iGEM 2015 is interested in making lab tools more accessible to the public. As part of the DIY revolution, we wanted to build lab tools capable of performing conventional tasks, such as thermocycling and incubation, at a fraction of the cost of typical machines. We also believe that these machines, due to their low cost, could be used as teaching devices in both biology and engineering classrooms.

Construction Hazard. Build at your own risk.

UMD PCR

Our first design for a DIY PCR machine was modeled after a more conventional PCR machine design. This first prototype used two peltier units, stacked on top of each other, to heat a customized aluminum block that sat on top of the two units and held the PCR tubes. In order for our system to have feedback, we embedded a temperature sensor in the aluminum block to detect the temperature of the wells that held the PCR tubes. The sensor then reported back to an Arduino UNO, which then regulated the energy flow to the peltier units, thereby heating and cooling the block and tubes while closing the control loop. However, after much testing, this design proved to be unoriginal, expensive, and inefficient. While the conventionality of the design itself did not pose an issue, we realized that the parts used to assemble it were not as well-known or easily accessible to the general public, which we felt would take away from the possible applications of this machine. In addition, although the price of this first prototype was relatively inexpensive in contrast to laboratory grade PCR machines, the price still ranged in the hundreds of dollars. Lastly and most importantly, the greatest issue with our design was the inefficiency of the hardware; we found that the peltier units were not able to cycle through the desired temperatures fast enough, e.g., the unit would take 5 to 10 minutes just to rise up to 95℃. After considering all of these factors, we began a redesign of our machine to better suit the needs of the “Do-It-Yourself” market.

The idea for our current thermocycler design first came into form when we found that our original prototype was not ramping up to the desired temperatures fast enough. Because of this problem, we looked into other options for heating the machine and, in the process, disassembled a hair dryer to find out how the heating mechanism worked. To our pleasant surprise, we found that the hair dryer was able to reach very high temperatures—much higher than the desired maximum of 95℃ for PCR—in a matter of seconds. We then made a decision to suspend construction on the peltier-centered thermocycler in order to see how successful we could be and how far we could go with making a rapid PCR machine out of a hair dryer. Before this decision, we took into consideration the danger of working with a hair dryer, failure due to uncertainty that the machine could be effectively controlled, and, on top of that, having less time to work on it. Nevertheless, we took the risk and are pleased to show you the results of our efforts.

@@ Line 207: / Line 207: @@
 <h1><b>Hardware</b></h1>
 The working internals of our PCR machine are comprised of hairdryer elements. With the exception of the hairdryers outer housing, the thermal fuse and bimetallic circuit breaker all other working components remain intact. The thermal fuse and bimetallic circuit breaker were shorted using copper wire in order to reach temperatures up to 95 within our machine. The outer plastic housing of the hairdryer was also removed to enable our machine to stand upright and fit PCR tubes. The hairdryers heating mechanism which utilizes a bank of nichrome wires and fan that distributes the heat remained untouched.
-</br>
-<img src="https://static.igem.org/mediawiki/2015/4/4b/UMD_PCR_temp_sensor.png" style="width:450px;height:600px;float:center;">
 </br>
 <img src="https://static.igem.org/mediawiki/2015/9/95/UMD_PCR_full_machine.jpg" style="width:450px;height:600px;float:center;">
 </br>
+<img src="https://static.igem.org/mediawiki/2015/4/4b/UMD_PCR_temp_sensor.png" style="width:330px;height:440px;float:center;">
+</br>
+<img src="https://static.igem.org/mediawiki/2015/5/51/2015-09-04_14.01.54.jpg" style="width:440px;height:330px;float:right;">
 <img src="https://static.igem.org/mediawiki/2015/1/11/UMD_PCR_soda_can.png" style="width:330px;height:440px;float:center;">
-</br>
 <img src="https://static.igem.org/mediawiki/2015/8/86/UMD_PCR_mica_sheet.png" style="width:450px;height:600px;float:center;">
-</br>
 <img src="https://static.igem.org/mediawiki/2015/2/22/UMD_PCR_hair_dryer_cover.png" style="width:450px;height:600px;float:center;">
-</br>
 <img src="https://static.igem.org/mediawiki/2015/d/d3/UMD_PCR_hair_dryer.png" style="width:450px;height:600px;float:center;">
 </br>

Difference between revisions of "Team:UMaryland/Design"

Revision as of 07:35, 18 September 2015

What is PCR?

Purpose

UMD PCR

Design

Hardware

Problems and Current issues