(6gc) Colloidal Electronic Cells As Building-Blocks for Synthetic, Tissue-like Scaffolds

Carbon nanotubes (1D), graphene (2D), transition metal dichalcogenides (2D) and other low dimensional materials possess desirable mechanical and electrical properties for incorporation into or onto novel colloidal particles, granting them unique electronic and chemical functions. We have shown previously that single-walled carbon nanotubes can be printed as flexible electronic ‘skins’ that harvest electrical power via molecular interactions with the embedded solvent environment (through an effect called ‘asymmetric chemical doping’).^[1-3] The electricity so harvested have been explored for on-board energy generation for particulate devices suspended in solution^{[4, 5]} and for in situ electrochemical conversion of small molecules.^[6] We also demonstrated the symbiotic engraftment of various 2D materials (e.g., graphene, MoS₂ and hBN, etc.) onto colloidal particles, making colloidal electronic systems with form-factors reminiscent to those of a biological cell (c.a. 10-100 µm in diameter),^[7] with the ability to perform autonomous functions such as optical energy harvesting, chemical detection, and digital memory recording.^[7-9]

These advances paved the way for us to build autonomous electronic ‘cells’ by wiring up synthetic ‘organelles’, combining the modularity that stems from micro-electronic platforms with the versatility that naturally arises in synthetic material systems. The ability to prepare these ‘cellular’ building-blocks at scale prompts yet further efforts to explore higher-order assemblies thereof, into hierarchical synthetic ‘tissues’ where complex functions emerge, via a suite of top-down and bottom-up techniques. Afterall, nature builds biological scaffolds with ordering that spans many orders of magnitude, affording remarkable control not only at the molecular (e.g., protein) level, but also on the micro- (e.g., organelle) as well as meso- (e.g., cellular) scale. Why should artificial materials design be constrained by control and heterogeneity only at the nanoscale (and occasionally at the microscale)? In the wake of recent developments in colloidal electronics fabrication, 3D printing and guided self-assembly, today’s chemical engineers are well poised to address the following problems: (i) how do individual devices assemble into higher-order structures with powerful attributes? (ii) how do simple interactions transmit information hierarchically? (iii) how can we harness and coordinate these interactions to efficiently create dynamic and complex systems?

I will present a proposed research program positioned at the intersection of materials design, chemical synthesis, and electronic device fabrication to help answer these questions that may bear far-reaching scientific and engineering significance. I will demonstrate how principles in chemical engineering provide us a unique toolset to build novel material architectures that address challenges in the medical, environmental, and materials sciences.

References

(* denotes equal contribution; † denotes corresponding author)

[1] SG Mahajan,* AT Liu,* and MS Strano† et. al. Sustainable power sources based on high efficiency thermopower wave devices. Energy & Environmental Science 9 (4), 1290-1298

[2] AT Liu,* Y Kunai,* and MS Strano† et. al. Electrical energy generation via reversible chemical doping on carbon nanotube fibers. Advanced Materials 28 (44), 9752-9757

[3] Y Kunai,* AT Liu,* and MS Strano† et. al. Observation of the Marcus inverted region of electron transfer from asymmetric chemical doping of pristine (n, m) single-walled carbon nanotubes. Journal of the American Chemical Society 139 (43), 15328-15336

[4] AT Liu and MS Strano et. al. Direct electricity generation mediated by molecular interactions with low dimensional carbon materials - a mechanistic perspective. Advanced Energy Materials 8 (35), 1802212

[5] AT Liu, G Zhang, and MS Strano.† Energy harvesting techniques mediated by molecular interactions with nanostructured carbon materials. Robotic Systems and Autonomous Platforms, 389-424

[6] AT Liu, Y Kunai, and MS Strano† et. al. Solvent induced electricity for in situ electrochemistry. manuscript in preparation

[7] P Liu,* AT Liu,* and MS Strano† et. al. Autoperforation of 2D materials for generating two-terminal memristive Janus particles. Nature Materials 17 (11), 1005

[8] VB Koman, AT Liu, and MS Strano† et. al. Colloidal nanoelectronic state machines based on 2D materials for aerosolizable electronics. Nature Nanotechnology 13 (9), 819-827

[9] AT Liu, and T Palacios,† MS Strano† et. al. Colloidal State Machines. Nature Reviews Materials. in revision

Teaching Interests:

Coming from a family of academics, I aspire to teach and conduct research in chemical engineering at a collegiate level. My undergraduate experience was in a way quite unique, in that I obtained two degrees at two different colleges (BA in Chemistry at Grinnell College and BS in Chemical Engineering at California Institute of Technology) through a transfer program. While my experiences the liberal arts college versus the engineering focused institute were different, one consistent theme throughout my academic career has been my commitment towards mentoring fellow classmates. I TAed for 5 different classes as an undergraduate and 2 more (the graduate level transport phenomena taught by Profs. Bill Deen and Martin Bazant, as well as the graduate level reaction engineering taught by Profs. Klavs Jensen and Michael Strano) since I joined MIT. My recitations were generally well-received and most student have found the extra notes I wrote after each lecture helpful. As a result, I was voted the best graduate TA for 2 separate years (2017 and 2019) in the department for the 2 classes I was involved in, and was nominated for the Goodwin Teaching Medal (awarded annually to one “conspicuously effective” TA at MIT). I have also served as a Teaching Development Fellow here at MIT and hosted regular workshops for my fellow TAs in the effort to foster a better pedagogical atmosphere across the entire institute. These experiences have further honed my teaching skills and prepared me for the future role as a teacher. In fact, being able to effectively communicate what I have learned and seeing it evoke passion among the students represent one of the most satisfying moments in recent memory.