Research Summary: We investigate the science of miniaturization, intelligent systems, and the interface between engineered and living systems.
Technical Perspective: The 62 publications below in peer reviewed journals with Impact Factor (ISI) > 10 (top 2% of all published journals) and/or citations >100 (Google Scholar) illustrate our most influential research contributions to science, engineering, and technology organized by specific focus areas.
Layperson's Perspective: Click on the Press link which includes articles written by others about our research achievements in a number of national and international news portals including The New York Times, Wall Street Journal, MIT Technology Review, Forbes Magazine, Scientific American, Popular Science, National Geographic, NPR, NIH, NSF, US Army, Zeit Weissen, EE Times, Times of India, C&E News, EE Times, Nature, Science, New England Journal of Medicine, Nature Nanotechnology, Nature Photonics, Nature Chemistry and Nature Physics.
Students in the laboratory continue to push the frontiers of science, engineering, and technology.
1. Active smart robotics, medicine and surgery using tiny untethered tools and devices
Imagine a tiny robot or machine that can sense its ambient, physiological, or marine environment and morph into different shapes to perform functional tasks like attach to or excise tissue autonomously! To achieve this long-standing engineering dream, the Gracias lab has pioneered, (a) sub-mm untethered thermobiochemically responsive robots, and (b) the concept of using MANY small surgical tools as opposed to ONE large one.
We developed the FIRST sub-mm sized, mechanized morphing structures such as grippers that can sense and fold or unfold in response to pH, temperature, proteases, glucose, L-glutamine, cell media, oxidative / reductive environments, and specific DNA sequences. Some designs can generate adequate forces during shape change and along with collaborators at the Johns Hopkins School of Medicine, we used them to perform the FIRST ever biopsies and tissue sampling experiments in the gastrointestinal tract of live animals.
20. Ghosh et al, Gastrointestinal resident, shape-changing microdevices extend drug release in vivo, Science Advances (2020) [Featured as the cover article]
19. Shi et al, Multicomponent DNA polymerization motor gels, Small (2020)
18. Jin et al, Untethered single cell grippers for active biopsy, Nano Letters (2020)
17. Ghosh et al, Active matter therapeutics, Nano Today (2020)
16. Xu et al., Soft three-dimensional robots with hard two-dimensional materials, ACS Nano (2019)
15. Cangialosi,* Yoon,* et al. DNA sequence-directed shape change of photopatterrned hydrogels via high-degree swelling, Science (2017)
14. Breger et al.,Self-folding thermo-magnetically responsive soft-microgrippers, ACS Applied Materials and Interfaces (2015)
13. Yim et al, Biopsy using a magnetic capsule endoscope carrying, releasing and retrieving untethered microgrippers, IEEE Transactions on Biomedical Engineering (2014)
12. Malachowski, et al., Self-folding single cell grippers, Nano Letters (2014)
11. Malachowski,* Breger,* et al., Stimuli responsive theragrippers for chemomechanical controlled release, Angewandte Chemie International Edition (2014)
10. Gracias, Stimuli responsive self-folding using thin polymer films, Current Opinion in Chemical Engineering (2013)
9. Gultepe et al., Biopsy with thermally-responsive untethered microtools, Advanced Materials (2013)
8. Solovev et al., Rolled-up magnetic microdrillers: Towards remotely controlled minimally invasive surgery, Nanoscale (2013)
7. Solovev et al.,Self-Propelled Nanotools, ACS Nano (2012)
6. Randhawa et al.,
Microchemomechanical Systems, Advanced Functional Materials
5. Bassik et al., Photolithographically Patterned Smart Hydrogel Based Bilayer Actuators, Polymer (2010)
4. Bassik et al., Enzymatically Triggered Actuation of Miniaturized Tools, JACS (2010)
3. Fernandes et al., Toward a miniaturized mechanical surgeon, Materials Today (2009)
2. Leong et al., Tetherless thermobiochemically actuated microgrippers, PNAS (2009)
1. Randhawa et al., Pick-and-place using chemically actuated microgrippers, JACS (2008)
2. Origami/Kirigami MEMS and NEMS
We live in a 3D world, but conventional microgip patterning (VLSI) while extremely well developed is inherently 2D. Imagine if we could take these inherently 2D VLSI electronic or optical devices and fold them into 3D shapes. We would then have truly 3D devices and metamaterials with micro and nanoscale dimensions manufactured in a highly parallel and cost-effective manner!
The Gracias lab has and continues to pioneer the concept of self-folding micro and nanoscale 3D metamaterials and devices. The laboratory has many FIRSTS including self-folding of the smallest patterned polyhedra, the concept of using trilayer hinges to make bidirectional self-folding kirigami, self-folding differentially UV crosslinked polymers using CAD masks.
15. Kwok*, Wang,* et al, Nano-folded gold catalysts for electroreduction of carbon dioxide, Nano Letters (2019)
14. Xu et al, Reversible MoS2 origami with spatially resolved and reconfigurable photosensitivity, Nano Letters (2019)
13. Rogers et al., Origami MEMS and NEMS, MRS Bulletin (2016)
12. Shenoy et al., Self-folding thin film materials: From nanopolyhedra to graphene origami, MRS Bulletin (2012)
Pandey et al., Algorithmic design of self-folding polyhedra, PNAS (2011)
10. Cho et al., Nanoscale Origami for 3D Optics, Small (2011)
9. Leong et al., Three dimensional fabrication at small size scales, Small (2010)
8. Cho et al., Curving nanostructures using extrinsic stress, Advanced Materials (2010)
7. Randhawa et al., Reversible actuation of microstructures by surface chemical modification of thin film bilayers, Advanced Materials (2010)
6. Bassik et al., Microassembly based on hands free origami with bidirectional curvature, Applied Physics Letters (2009)
5. Cho et al., Self-assembly of lithographically patterned nanoparticles, Nano Letters (2009)
4. Bassik et al., Patterning thin film mechanical properties to drive assembly of complex 3D structures, Advanced Materials (2008)
3. Leong et al., Thin film stress driven self-folding of microstructured containers, Small (2008).
Leong et al., Surface tension driven self-folding polyhedra, Langmuir (2007)
1. Gracias et al.,Fabrication of micrometer-scale, patterned polyhedra by self-assembly, Advanced Materials (2002)
3. Biomimetic folding and assembly of 3D drug delivery, tissue engineering and biomedical devices
The human body is incredibly well patterned on the mm, micro, and nanoscale in complex 3D, curved, and folded architectures. Humans are unable to replicate these complex micropatterned environments with biologically relevant materials. The Gracias laboratory has and continues to pioneer morphogenesis inspired approaches of self-folding biomedical devices including those for drug delivery, tissue engineering and surgery. The laboratory has many FIRSTS including introducing the concept of "bio-origami" hydrogels for tissue engineering and "self-folding microfluidics and capsules"
11. Jin,*Bhatta,*Pagaduan,*Chen,* Biomimetic human small muscular pulmonary arteries, Science Advances (2020)
10. Cools et al, A micropatterned multielectrode shell for 3D spatiotemporal recording from live cells, Advanced Science (2018)
9. Jin,* Li* et al., Mechanical Trap Surface Enhanced Raman Spectroscopy (MTSERS) for 3D surface molecular imaging of single live cells, Angewandte Chemie (2017)
8. Xi et al., Molecular insights into division of single human cancer cells in on-chip transparent microtubes, ACS Nano (2016)
7. Mannoor et al., 3D printed bionic ears, Nano Letters (2013)
6. Jamal et al., Bio-origami hydrogel scaffolds composed of photocrosslinked PEG bilayers, Advanced Healthcare Materials (2013)
5. Fernandes et al., Self-folding polymeric containers for encapsulation and delivery of drugs, Advanced Drug Delivery Reviews (2012)
4. Randall et al.,
Self-folding materials and devices for biomedical applications, Trends in Biotechnology
3. Jamal et al., Differentially photo-crosslinked polymers enable self-assembling microfluidics, Nature Communications (2011)
2. Azam et al, Self-folding micropatterned polymeric containers, Biomedical Microdevices (2011)
1. Randall et al., 3D lithographically fabricated nanoliter containers for drug delivery, Advanced Drug Delivery Reviews (2007)
4. Folding atomically thin films
Imagine if we could take atomically thin paper and fold it into 3D shapes. We might then be able to make light weight devices for wearables or robots or even create new types of material configurations. To enable this engineering dream, the Gracias laboratory has and continues to pioneer the self-folding and origami engineering of atomically thin films like graphene and MoS2. As one of our pioneering FIRSTS, we invented "thermally responsive self-folding graphene"
3. Xu et al., Self-folding hybrid graphene skin for 3D biosensing, Nano Letters (2019)
2. Xu et al., Ultrathin shape change smart materials, Accounts of Chemical Research (2018)
1. Xu et al., Ultrathin thermoresponsive self-folding 3D graphene, Science Advances (2017)
5. Self-assembly by programmed aggregation and folding
Nature fabricates complex structures like cells or even mountains by self-organization, but engineers do not know how to do this. Imagine, for example if we could self-organize a computer from free floating chips or transistors. To realize this engineering dream, PI Gracias and the lab has and continues to pioneer the self-assembly of arrayed, 3D, integrated devices by aggregation and folding. Some of our pioneering FIRSTS include "self-assembling circuits with serial and parallel connectivity", "self-folding of polyhedral sensors and 2D chips", and "self-aggregating THz metamaterials"
4. Pandey et al., Algorithmic design of self-folding polyhedra, PNAS (2011)
Jacobs et al., Fabrication of a cylindrical display by patterned assembly, Science (2002)
2. Boncheva et al., Biomimetic self-assembly of a functional asymmetrical electronic device, PNAS (2002)
1. Gracias et al., Forming electrical networks in three dimensions by self-assembly, Science (2000)
6. Spatio-temporally controlled chemistry
In chemistry laboratory and daily life, we are accustomed to do chemical reactions by mixing reactants in flasks and beakers, quite unlike what happens in and around living cells where reactants are encapsulated in organelles and chemistry is controlled precisely in space and time through programmed reaction-diffusion. The Gracias lab has and continues to pioneer "spatiotemporally controlled chemistry" including the first demonstration of spatially controlled microscale chemistry with precisely patterned porosity on microcapsules. We also invented and patented a"chemical display" which can generate animations not by electronics and optical pixels but by spatiotemporally programmed diffusion of dyes or fluorescent chemicals. This display does not need any batteries or external power.
3. Kalinin,* Pandey,* et al., A chemical display: Generating animations by controlled diffusion from porous voxels, Advanced Functional Materials (2016)
2. Ye et al.,
Remote radio frequency controlled nanoliter chemistry and chemical delivery on substrates,
Angewandte Chemie International Edition
1. Leong et al., Spatially controlled chemistry using remotely guided nanoliter scale containers, JACS (2006)
7. Surface science, spectroscopy, and other interesting stuff
The world around us if full of interesting problems. Our students are problem solvers and we often work on a variety of problems to make many other significant innovations.
6. Chowdhury et al,Substrate directed synthesis of MoS2 nanocrystals with tunable dimensionality and optical properties, Nature Nanotechnology (2019)
5. Ye et al., Probing organic field effect transistors in-situ during operation using SFG, Journal of the American Chemical Society (JACS) (2006)
4. Ye et al., Kinetics of ultraviolet and plasma surface modification of poly(dimethylsiloxane) probed by sum frequency vibrational spectroscopy, Langmuir (2006)
3. Mayer et al., Micropatterned agarose gels for stamping arrays of proteins and gradients of proteins, Proteomics (2004)
2. Gracias et al., Molecular characterization of polymer and polymer blend surfaces. Combined sum frequency generation surface vibrational spectroscopy and scanning force microscopy studies, Accounts of Chemical Research (1999)
1. Gracias et al., Continuum force microscopy study of the elastic modulus, hardness and friction of polyethylene and polypropylene surfaces, Macromolecules (1998)