Thursday, August 6, 2015

Today I delivered my final presentation, "Fabrication of Novel Nanomaterial Tungsten Disulfide (WS2) Nanopores for Solid-State DNA Sequencing" for my REU fellowship at the Nano/Bio Interface Center (NBIC). 

My project abstract: Tungsten disulfide (WS2) is a novel nanomaterial that offers promise to create nanopores for easy and efficient detection of DNA translocation with high spatial resolution. In this work, nanopore membranes are fabricated, a method is designed for the transfer of WS2, WS2 flakes are characterized for nanopore application and transferred to membranes. Semiconductive properties of WS2 indicate promise for WS2  nanopores which will be drilled in the WS2 flakes. Silicon wafers were prepared using a standard method to form ~50 um x 50 um membranes for nanopore drilling. The created membranes were observed for uniformity and their size noted using optical microscopy. Scanning electron microscopy (SEM) was employed to visualize the membranes and focused ion beam (FIB) ~50 nm holes were sculpted. Flakes of WS2 were acquired and images were captured using optical microscopy, height profile characterized by atomic force microscopy (AFM), and Raman spectroscopy used to observe monolayer or multilayer flakes. A stamp transfer method was designed to achieve optimal alignment of one flake to a membrane. Testing of the stamp transfer indicated a touch, release set-up that provided visual observation using optical microscopy. This provided the ability to visually align WS2 flakes over membranes. Using minute motion, the flake was lowered to the microscope stage and contact is made with the membrane. The results of my contribution - wafer fabrication, SEM imaging, FIB drilled holes, designed stamp transfer, capturing optical microscopy images, atomic force microscopy (AFM) and Raman profiles for WS2  flakes, and transfer of WS2 to membrane indicate that the suspended WS2 is ready for nanopore drilling. Once a nanopore is drilled in the suspended WS2 flake, the Drndic group will conduct further experiments - Raman spectroscopy to check quality of 2D suspension,  atomic force microscopy (AFM) to observe the suspended thickness and height profile, and use methods to determine device noise and electronic frequency -  will assist in determining the viability of WS2 nanopores as gateways for DNA sequencing.   

I would like to give special thanks to Dr. Drndić and the University of Pennsylvania NBIC for hosting me this summer, my mentors Gopinath and Paul, and the Drndić lab for their support and encouragement. Through my 10 week research project, it was exciting to explore nanotechnology, learn cleanroom techniques, and become certified to use new equipment. The Drndić lab group became my summer science family. I will miss our lab's daily lunches together, the accompanied crazy idea sharing, David's bread baking, and the fun times we have shared. I'm looking forward to coming to PennApps in September to hack as a member of the Drndić lab coding team!

Tuesday, July 21, 2015

This past weekend I saw paintings by the painters who - during the late 1800s - were considered "painters of mere impressions;"  the impressionists. The Philadelphia Museum of Art's special exhibition is Discovering the Impressionists. Philadelphia is the only US venue for the exhibition. I went with my mom and Holly - yay Holly for being awesome and having an art membership. The exhibition features the art dealer Paul Durand-Ruel who saw promise in the impressionist style and supported artists including Monet, Renoir, Degas, Cassatt, and Pissaro. It was fascinating to learn of the criticisms that the impressionists and Durand-Ruel encountered and how the impressionists gaining international fame. 

Following our visit to the Impressionist Exhibit at the Museum of Art, we returned to my dorm -  the Philly IHouse -  to take part in the IHouse Celebration of Eid. IHouse hosts a Feast of Eid which is open to residents, guests, and the public. At the feast, I learned about Eid and listened to stories from some of the Muslim IHouse residents. Eid marks the end of Ramadan which is the Islamic holy month of fasting. 

Following Eid, I met up with Christina and other PennApps fellows and we took a nice stroll down Locust Walk. It was pretty to see my lab lit up. 

On Sunday, I returned to the Philadelphia Museum of Art with Christina, Shalini, and Alice. The passes mom, Holly, and I had used on Saturday were good for next day general admission to the museum - wohooo. 

I am very excited to research in the lab this week. A miracle occurred and the WS2 flakes finally came! They are so beautiful (wipes tear of joy). 

Thursday, July 16, 2015

On Saturday, I took the bus to NYC to meet up with my friend Abril for the weekend. One of the members from my lab group was on the bus as well; it was a good of that weekend being perfect for a trip to NYC. When I arrived, we went for lunch at Smorgasbord in Brooklyn, a food market on the waterfront. 

After a brief ice cream trip, we met up with HackNY fellows to go to The New Pornographers and Thao concert. 

The concert was part of Celebrate Brooklyn at Prospect Park Bandshell. It was fun and relaxing listening to the indie rock music.

Sunday I attended the NYC National Center for Women & Information Technology (NCWIT) intern brunch with Abril. It was awesome to meet fellow college and also high school girls who are pursuing computer science or related technical fields. It was especially nice to reunite with my Google Computer Science Summer Institute (CSSI) friend Megha. Megha, Samuel, and I worked on the CSSI final project together. Last summer, we built an elegant, easy and free e-card app geared for our generation. You can check it out at:

It was experiment time again on Monday. Back in the lab, I am doing graphene transfers. I am also receiving training sessions on the forced ion beam (FIB). The FIB is used to drill nanopores in wafer membranes and in whatever 2D overlaying material. 

This week, I have had the chance to explore Philly, attending the Philly Interns party at the Comcast Center and the Philly Tech Meetup at the Science Center. At the party at the Comcast Center, I met my friends Caroline who goes to Carnegie Mellon University and Christina who goes to UC Davis. Both are interning  at Philadelphia area startups as part of the PennApps Fellowship program. They introduced me to other fellows. 

I am having a great time with my NBIC REU group. As part of our weekly brown bag seminar, we received a presentation on graduate school from the director of admissions for the Materials Science and Engineering (MSE) graduate program. Following the session, we took group pictures for the website. The 10 REU students and 4 French Grenade Exchange students are pictured below. These are our normal expressions.

Thursday, July 9, 2015

This blog entry features: family, the Fourth of July, Pride, and a method that I re-designed for the tungsten disulfide flake transfer.

On July 2nd, I celebrated the day the Continental Congress approved the Declaration of Independence  with my mom, dad, and Uncle Paul. We attended  the International House's  BBQ party which had the type of food typically expected at BBQs. Following the party, I gave them a tour of the nanofabrication center and of my physics lab. My mom brought decorative red-white-blue sprinkled brownies for my lab group to enjoy and we went to drop them by the lab. It was around 9pm and David - a post-doc - and Will - a PhD student - were in the lab still diligently at work. Lesson: I guess it is okay to interrupt someone if it is to give them food (especially brownies). 
On Friday the 3rd, I attended the Philadelphia Fourth of July block party between 5th and 6th streets with some of my REU friends. I did not end up attending the celebrations downtom on the 4th; instead, I choose to spend time enjoying University City. From my apartment window, I saw a fireworks display. 

I volunteered at the Philadelphia Pride Block-party on Sunday. It was fun to assist and I was proud to support the movement and watch as the new pride sidewalks were opened to mark the Supreme Court ruling of nationally legalized same-sex marriage. 

In the lab this week, my research has focused on designing a stamp transfer method to achieve optimal alignment of one flake of tungsten disulfide (WS2) to a membrane on the silicon wafer. Previously, I had designed the set-up of a micro-manipulator that will assist in this transfer. In the chemical part of our lab, I make a gel that will be used to hold the flakes. I then secure the gel to the micro-manipulator using a polyurethane coating. To test the stamp transfer, I visually observe alignment under the optical microscope and then lower the gel to contact with the membrane. Using minute motion, the apparatus is lowered to the microscope stage. Hopefully the contact works as well when the fresh WS2 arrive.
I look forward to enjoying dinner tonight with my grandma and mom. Mom is stopping in Philly on her way to taking grandma to the shore for the weekend.

Thursday, July 2, 2015

It's 4th of July week, and the adventures continue at UPenn and in the city of Philadelphia. On Sunday night, the celebrations began as I attended the fireworks show at Penn's Landing with some of my REU friends. 

This week, I used my Penn card to enter the Wharton business school. My lab friend Paul told me he discovered what he thinks is one of the best views of Philadelphia from Wharton's rooftop rooms. Sadly, the room that showcases the best view was locked. However, I was still able to enjoy my Wharton visit and some nice side views of center city.

On Wednesday, I delivered a mid-way presentation of my research to the other REU students. I'm having a great time in my lab and cannot believe the research fellowship is already halfway over! After the lab, my friend Connie and I are having fun wandering into shops downtown University City. We shared a special break from lab work with a fro-yo moment this afternoon. 

The nanofabrication center is having work done so many of the equipment is currently not operational. This delays work but hopefully everything will be running next week. I have been working on designing an apparatus to assist the transfer of the Tungsten Disulfide (WS2) flakes onto membranes on the silicon wafers. The alignment must be precise, matching the flake and membrane accurately at the micron level. 

In the lab, I have also begun learning a simulation program to create an animation for WS2 transfer to add to our YouTube channel. We already have a few awesome simulations for graphene and phosphorine - can't wait to add WS2 transfer. I also started "The Cleanroom Chronicles" cartoon.

As a final note, never follow the procedure for HF - it is not safe. This upcoming weekend: GO USA! Hope everyone has a great and safe 4th of July.