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Saad Bhamla @BhamlaLab
, 26 tweets, 14 min read Read on Twitter
In our philosophy of frugal science, we are sharing today our latest tool from the lab: a 20-cent electroporator, which we call an ElectroPen. Almost a year ago, when I started my lab @GeorgiaTech, a team of high school students @lamberths_iGEM led by @jastandeven reached out...
as part of iGEM, these students were engg living cell sensors for disease diagnostics, but needed an electroporator for genetic modification. Electroporators are expensive. They cost between $2500-$10,000, and that doesn't include the cost of cuvettes, which adds up...
Instead of buying an electroporator from my start-up, I challenged us to build a frugal one - since they had come to the right place. We were the frugal lab and in the past I had invented the 20-cent paper centrifuge (paperfuge). So we set the goal to build <$1 electroporator!
One of the highschool students - Gaurav took this challenge seriously. He is a high-schooler, who is the first-author on this manuscript and has made all the figures + done all the analysis in this paper! I am super proud of him! Btw, the teacher is also co-author @jastandeven
The heart of an electroporator is essential a large voltage pulse ~5000 Volts, but for a very short period of time, 1-5 milliseconds. So, we brainstormed for a few months for how we could generate high voltages without electricity. Take a few minutes to think what you would do...
We ultimately found inspiration in a common household gas lighter! When you light your bbq or stove and hear a click sound followed by a spark - that is due to piezoelectric effect discovered by the Curie brothers, Pierre & Jacque in 1880
The next question was - was this sufficient voltage for electroporating E.Coli? So, we measured the voltage from many different lighters and discovered it had a peak of ~2000 Volts and decayed with a time constant of ~5 ms! The reproducibility of the data surprised us...
We ran almost 50 measurements with 5 users - including the high school teachers, professors and students.. The puzzle was how could a mechanical device like an inexpensive lighter provide such consistent voltage values? This is when we realized...
We didn't know how a lighter actually works. So, we decided to take one apart from a kitchen lighter -- the funny joke here is that my high school students who led this project couldn't buy the lighter themselves due to <21 age :) Despite their arguments that it was for science..
Turns out the lighter is very cleverly engineered, with multiple springs, a hammer, a piezoelectric crystal and a 3D-latch that allows the metal hammer to build energy as the spring is compressed by our fingers. Once the hammer reaches critical point, it releases by twisting free
We recorded the whole motion using a high-speed camera - see below.
What we were amazed by is the high-speeds the hammer was traveling at - it achieved an acceleration of 30,000 m/s2 or 3000g-forces. This results in about 10N force exerted over a very tiny area of the piezo crystal surface...
What is neat about this experiment, is that once we know the experimental parameters such as force etc.. we can use piezoelectric theory to predict the output voltage ~2700V, which is in the same range as experimentally measured! So experiment and theory are in good agreement.
Gaurav also made a detailed schematic of how a gas lighter works - in case you are ever curious! I always say, even a seemingly simple object can have very complex physics and engineering, if you look closely enough...
Now that we had all the physics done, we 3d-printed our electropen and were ready to test if we could electroporate E. Coli cells. Before we did that, we also wanted to solve the challenge of expensive cuvettes..
So we developed our own low-cost version using glass slides and aluminum foil - we show that you can make these cuvettes from wood, plastic, glass etc very easily.
Now, for demonstrating the ElectroPen works, we transformed plasmid into electrocompetent E.Coli cells and showed same order of magnitude transformation efficiency..
To further show how easy-to-use and rapidly deployable the electropen is, we shared instructions with other iGEM student teams at UGA and Taipei @iGEM_TAS who independently evaluated the electropen and validated the results...
So, now we are launching phase 2 - if you are excited to collaborate with us, please reach out to us -
The bioRxiv paper is up here -…
Also if you watch the SI videos (…), you will see that Gaurav has put in lots of effort to provide step-by-step instruction to make your own ElectroPen
to making the low-cost custom cuvettes..
to properly and safely running electroporation with the ElectroPen...

We also have a forum on our website to discuss and help you troubleshoot.
Last , I have to acknowledge $$ support from @NSF_BIO #MCB and @MindlinFndtn to train high-school students in synthetic biology. And if syn biology hardware is too expensive for budget-constrained labs, then to invent frugal ones. FutureOfSTEM = collaborn(high-school + higherEd)
Welcome to Twitter Gaurav @byagathvalli. He is the awesome high schooler who led this work in my lab. He is applying to college, so please keep your eye out for his application. Any program would be lucky to land him.
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