BM10: Bioinspired Interfacial Materials with Superwettability

Dimos Poulikakos, ETH Zürich

Enhancing Superhydrophobicity and Icephobicity through Surface Flexibility Inspired by Butterfly Wings

Written by Aashutosh Mistry

Butterfly wings have incited a bit of scientific interest for fluid dynamists as they are very hydrophobic. Surface investigations have revealed that the surface itself is superhydrophobic with contact angles in the range 155°–165° (with 5° hysteresis). Since butterfly wings are flexible structures, an associated question is the role of flexibility on hydrophobicity (i.e., if it promotes or discourages the intrinsic hydrophobicity of the wings). Dimos Poulikakos and his research group at ETH Zürich have been investigating the importance of surface flexibility on hydrophobicity as well as icephobicity. They found that when water drops impact the solid substrate at a finite velocity, resulting rebound is higher for a more flexible surface, thus highlighting a positive correlation between flexibility and hydrophobicity. Even the harmonics of drop oscillations are found to differ based on the extent of surface flexibility. Based on their experiments, they found that the mass weighted relative velocity of drop and the surface is an important velocity scale. Use of this relative velocity collapses the results with both rigid and flexible surfaces onto a unique scaling relation. When extending such studies for supercooled surfaces (surface at temperatures below freezing point of water), they made some interesting observations. The entire water drop does not solidify instantaneously. Rather in many instances they found that the drop rebounds (again depending on surface flexibility) and freezes mid-air. A spontaneous formation of minute icicle network is observed inside the drop upon contact. Icephobicity is practically quite relevant because ice formation on operating surface can largely hinder their performance. The present set of results show that if the surface is assigned a control motion, solidifying drops will not adhere to the surface. Thus, it is observed that the surface elasticity and wetting properties have a collaborative effect that is tunable through altering substrate areal density, stiffness, and damping.


Irene's favourite talk from Friday

Yes guys, I am still kicking! I am one of the fortunate people that had a talk on Friday and had to stick to the very end of the conference. On Friday morning I attended the joint session on Nanoparticle Bioprobes, where I was also giving a talk on gold nanorods. From that session, I really enjoyed Dr. Teri Odom's talk on gold nanostar probes for imaging and therapeutics. Dr. Odom and her team at Northwestern University have developed reliable synthetic methods to prepare reproducible dendritic gold nanostars of about 50 nm in maximum diameter. These multidentate nanoplatforms are biocompatible and have a size that theoretically should be ideal for long circulation times. But not only have they made the particles and tested their biocompatibility: they also have developed an optical technique based on differential interference contrast microscopy, or DIC, to follow the position and rotational dynamics of these nanoparticles in real time in cell cultures. How cool is that?


Thank you MRS!

This MRS was very special to me. I made some great friends through blogging (Irene, Rahim, Andy, Hortense). I stretched my comfort zone by attending a very interactive session on Using Improv in Communication where I learned some great tips on how to make an effective elevator pitch. I gained professional skills through the invaluable sessions at The Hub on networking, interviewing, and negotiating a job offer (and met some amazing people). I was also able to get a critique on my resume and a professional head shot taken (never realized how much work goes into getting that perfect headshot!)

Because of the wide reach of research in materials science, I got to learn about things I have been interested in but never had the chance to do a thorough lit review. Attending the different talks is almost like a lit review in motion. 

In addition, I tried some of the "must" restaurants in Boston, visited the campus of MIT and Harvard, and I have started to fall in love with Boston with its fall colors and architecture. And how could I forget that due to this conference, I was also able to see actual artifacts from the ancient Egyptian era.

None of this would have been possible without the MRS conference. So thank you MRS for hosting this amazing conference every fall. I hope to continue being a part of this.


Irene's talk - using Au NPs for drug delivery!

One of the MRS Meeting Scene bloggers, Irene, was also presenting her research on using Au nanoparticles for drug delivery. So other than the topic being one I am interested in, I was also supporting my fellow blogger colleague!

Irene Andreu, a postdoc at Simon Fraser University in British Columbia, Canada, explained very well how stuff works - they start with Au nanorods, attach functionality linkers to them, when the nanorods reach the particular cell that is targeted, they are stimulated by light or heat that causes them to release the drug. 

Why nanorods instead of spherical nanoparticles? Because the nanoparticles have absorption peak in the visible spectrum while the nanorods have absorption peak in the near IR. Since human bodies are not transparent to visible light but are transparent to near IR, you have to go for nano-rods instead of spherical nanoparticles.

They tested how their nano-rods would react to a laser light by using a femto-second laser at high power. They found that the absorption peak blue shifts more towards visible range. This means that if they used these particles for drug delivery, then the absorption at near IR would be weak and inhomogeneous, so some of them might not even release the drug. 

However, she clarified that this laser is way more powerful than the ones used in clinical settings. So Irene might find out that her Au nano-rods get the job done in a real-life application!


Surface Enhanced Raman Spectroscopy for bio-imaging

They say the firsts always hold a special place in your heart - first love, first car, your first apartment. When I began research as a graduate student, I worked on plasmonic nanoparticles - something completely different from the amorphous oxide semiconductor that I am doing my dissertation on. My first publication was on using plasmonic Ag nanoparticles to understand thin film growth, and during that study, I learned how to do Raman spectroscopy...and I discovered the strong surface enhanced Raman (SERS) signals caused by the Ag nanoparticles. You can say in a way that was my first research love. I even wanted to pursue a project on SERS using AgFe nanoparticles, but never got around to it because my current project took priority.

Therefore the talks today in Hynes 311 on SERS were of great interest to me. Sevde Altuntas from the TOBB University of Economics and Technology in Ankara, Turkey presented her research on developing nano-crater and nano-bump templates of aluminum oxide that she coated in 20 nm of Au to create SERS active membranes. By using methylene blue and congo red, two chemicals with well known Raman signatures, she and her group quantified a SERS enhancement factor of 2.3x10^5 times! In addition they were able to show that their SERS active membranes were stable for up to one month.

Right after her, Yu-Chuan Ou from Vanderbilt University showed the application of star shaped Au nano-antennae for SERS effect in Raman imaging. She and her group targeted accurate identification of PD-L1 expression in tumor, which is currently an inaccurate process. They were able to carry out in vivo imaging of biomarkers in a fast and efficient manner. In addition, they were also able to dissect the tumor cells to analyse exactly where the biomarkers accumulated. I am not very well-versed in biological terms, but what I got out of the talk was their method could accurately identify biomarkers in vivo, which to me is super cool!

After I finish my PhD, I would like to transition into the field of plasmonic nanoparticles being used for biological applications - so this was a useful session for me to know what's going on in this field.


Boston Harbor and Little Italy

Last night I went with a friend to explore the Boston harborside and try some delicious Italian food.

Apparently Giacomo's on Hanover St. is worth the hour long wait in line. Luckily, when we went the line was so short that we waited for about 10 minutes at max. The restaurant is cash-only so make sure you get some (if you forget to get cash, there's an ATM machine right across the street from the restaurant). The food was hands down the best Italian food I had! 

Next on the "to-do" list was Mike's Pastry. They have a wide variety of Italian pastry, but what surprised me was that everything was supersized! The eclairs were more like the size of large hot dogs! I got a tiramisu, but the cream was a bit too heavy for my taste. But hey, you might like it so check it out!

In addition, there were beautiful Christmas lights all around Quincy market. All-in-all, a superb evening!

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Day in the life of a Symposium Assistant

This year I had two colleagues from UC Berkeley who were symposium assistants. Since I have never been one (and always wanted to be one) I asked them what the experience was like. Here's what they said:

  1. You have to attend the Symposium Assistant training, which takes place typically the evening before all the sessions begin. The training is mandatory, where they are explained their duties, and shown how to operate the projector with different types laptop interface (HDMI vs VGA cable). 
  2. They must arrive 30 minutes prior to the beginning of each session. Upon arrival they get the list of talks to put outside of their designated room (yes those printed sheets you see with the details of the talks? It's the symposium assistants who make sure they are there)
  3. Before the session begins, they make sure the powerpoints of all the speakers load without any technical difficulty. They also help the speakers with the microphone and laser pointer.
  4. They have to get the speakers to sign-in on the list of talks. They also keep attendance for each talk.
  5. Once the session is over, they take the sign-in and the attendance sheet and return it to their "boss"

The perks: they get $10/hour and also reimbursement of their registration fee if they manage at least four sessions.

Although the tasks are not difficult, think about it, they have to arrive at the conference center by 7:30AM, and they barely get much time for lunch since the afternoon sessions typically start at 1:30PM. So make some noise for your symposium assistants!

PS: it's a shame I don't have photos with my symposium assistant friends!


Best Poster Award Winners - Thursday

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Shan Yan, State University of New York
BM06.12.13
Flexible Electronic Devices with Functional Nanoparticles Towards Wearable Biosensors for Human Health and Performance Monitoring

 

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Seirjiro Fukuta, Yamagata University
EM01.10.10
Poly(3-Hexylthiophene)-b-Poly(isobutene)-b-Poly(3-hexylthiophene) for Stretchable Semiconductor Application

 

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Kostianty Turcheniuk, Georgia Institute of Technology
ES04.19.49
Nanoporous Copper Synthesized via De-Alloying of Copper-Calcium Alloys to Accommodate Lithium Titanate for Asymmetric Supercapacitors



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Kriti Agarwal, University of Minnesota
NM02.11.43
Uniform Plasmon Hybridization and Volumetric Field Enhancements in Graphene Nanocubes

 

NOT PICTURED

Rohit Saraf, University of Waterloo
ES01.13.53
Photo Assisted Poling Effect in Organic-Inorganic Hybrid Perovskite and Its Application for Self-Powered Tactile Sensors


Graduate Student Awards

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Gold  Winners:

Longji Cui, University of Michigan

Yuzhang Li, Stanford University

Naveen Mahenderkar, Missouri University of Science and Technology

Patrick Pietsch, ETH Zürich

Michelle Sherrott, California Institute of Technology

Birgitt Stogin, The Pennsylvania State University  *Nowick

John Sypek, University of Connecticut

Sirimuvva Tadepalli, Washington University in St. Louis

Ryan Truby, Harvard University


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Silver Winners:

Arif Abdullah, University of Illinois at Urbana-Champaign

Dennis Christensen, Technical University of Denmark

Maher Damak, Massachusetts Institute of Technology

David Frazer, University of California, Berkeley

Yongping Fu, University of Wisconsin–Madison

Alex Ganose, University College London

Grace Gu, Massachusetts Institute of Technology

Yuanwen Jiang, The University of Chicago

Kang Hee Ku, Korea Advanced Institute of Science and Technology

Prashant Kumar, University of Minnesota Twin Cities

Albert Liu, Massachusetts Institute of Technology

Akanksha Menon, Georgia Institute of Technology

Akinola Oyedele, Oak Ridge National Laboratory

Jessica Swallow, Massachusetts Institute of Technology

Elizabeth Tennyson, University of Maryland

Yu Tian, University of Delaware

Chen Wang, University of California, Los Angeles

Wennie Wang, University of California, Santa Barbara

Yiping Wang, Rensselaer Polytechnic Institute

Shuya Wei, Cornell University

Rong Ye, University of California, Berkeley

Hyojin Yoon, Pohang University of Science and Technology