There is always something to learn outside your lab. In this digital era where micrometer-scale systems are incorporated in every aspect of our lives, one can be curious to learn more about how these tiny machines make the world go around.
In the previous SOS lectures about microsystems, Prof. Tixier-Mita from IIS, UTokyo introduced what microsystems are, their function and how they work and sense. In the last session, we even got a chance to visit Prof. Tixier-Mita’s laboratory in Komaba campus to fabricate our own microfluidic devices. It was truly an amazing experience and we just can’t wait to share this with you!
Before the start of the experiment, Prof. Tixier-Mita showed us what a real microfluidic chip looks like under the microscope.
Then the professor introduced the experiment. It might sound complicated at first, but the way it was explained made it so easy. First, we have a master mold with a predefined pattern. We pour PDMS, which is a polymer that will solidify under high temperature onto the mold to replicate the pattern. Then, we release the replica and drill on the PDMS to expose the inlets. Then put PDMS in contact with a glass slide in order to fix the PDMS. Finally, we pipette inks through the inlets to visualize the microtubule pattern we created.
Everyone was so engaged and listening carefully so that we don’t mess things up. Precision was key!
Moving on to the next phase, first, we mixed the slim-like PDMS with another reagent called slipot 184 for better solidification. Since small bubbles introduced by stirring may block the microtubules we made, we put the PDMS mixture into a vacuum machine to pump out the bubbles before moving to the next step.
The elevated pressure difference inside the machines facilitates getting rid of all the bubbles in the PDMS. The whole process took about 20 mins to complete.
When all bubbles were removed, the PDMS mixture was ready to pour onto the black master mold to replicate the pattern on the master mold . This step should be done very carefully as the PDMS mixture is quite slimy and it is easy to over pour it.
Then, Prof. Tixier-Mita put our samples on a heater and set the temperature at a constant 90 oC for about 30 mins until the PDMS fully solidified.
We then cut out the hardened PDMS, and punched holes through the four inlets, and placed the PDMS on a glass slide. At this stage we saw the pattern created, which was simply two lines with four inlets.
To be able to observe the microtubules pattern easily, inks was injected through the inlets. There were two microtubules, one with larger diameter (blue) and the other with smaller diameter (red). We tried to create a beautiful gradient of color by injecting different ink colors in each inlets of a microtubule. Well it did not work out so nicely, at least for my sample…
When we finished, it was almost 5pm. Time passes so quickly if you don’t get enough of doing something you enjoy.
We learned something quite unfamiliar, yet at the same time closely related to our own disciplines.
In my case, it was hard to believe that I just created the basic architecture of a blood glucose meter and the flow cytometry that I frequently use in my own experiments. It’s difficult to imagine how we would have had such easy access to this kind of knowledge without the SOS sessions, which had undoubtedly expanded our understanding of the world we live.
At the end of the experiment, we were happy to know that everyone can take their newly created microsystem with them. Prof. Tixier-Mita kindly prepared Falcon tubes so that we can carry our souvenirs easily without breaking them. All participants were also presented with a certificate for successfully completing the sessions.
Thank you, Prof. Tixier-Mita and all the attendees for sharing this memorable experience with me! Hope to see you and any new faces in subsequent SOS sessions!
