Shutao Qiao

Multifunctional wearable devices for diagnosis and therapy of movement disorders

Wearable systems that monitor muscle activity, store data and deliver feedback therapy are the next frontier in personalized medicine and healthcare. However, technical challenges, such as the fabrication of high-performance, energy-efficient sensors and memory modules that are in intimate mechanical contact with soft tissues, in conjunction with controlled delivery of therapeutic agents, limit the wide-scale adoption of such systems. Here, we describe materials, mechanics and designs for multifunctional, wearable-on-the-skin systems that address these challenges via monolithic integration of nanomembranes fabricated with a top-down approach, nanoparticles assembled by bottom-up methods, and stretchable electronics on a tissue-like polymeric substrate. Representative examples of such systems include physiological sensors, non-volatile memory and drug-release actuators. Quantitative analyses of the electronics, mechanics, heat-transfer and drug-diffusion characteristics validate the operation of individual components, thereby enabling system-level multifunctionalities.

Integrated flexible chalcogenide glass photonic devices

Photonic integration on plastic substrates enables emerging applications ranging from flexible interconnects to conformal sensors on biological tissues. Such devices are traditionally fabricated using pattern transfer, which is complicated and has limited integration capacity. Here we pioneered a monolithic approach to realize flexible, high-index-contrast glass photonics with significantly improved processing throughput and yield. Noting that the conventional multilayer bending theory fails when laminates have large elastic mismatch, we derived a mechanics theory accounting for multiple neutral axes in one laminated structure to accurately predict its strain-optical coupling behavior. Through combining monolithic fabrication and local neutral axis designs, we fabricated devices that boast record optical performance (Q=460,000) and excellent mechanical flexibility enabling repeated bending down to sub-millimeter radius without measurable performance degradation, both of which represent major improvements over state-of-the-art. Further, we demonstrate that our technology offers a facile fabrication route for 3-D high-index-contrast photonics difficult to process using traditional methods.

Cephalopod‐Inspired Miniaturized Suction Cups for Smart Medical Skin

M. K. Choi, C. Choi, J. Kim, D. J. Lee, M. Kim, W. Hyun, S. J. Kim, Prof. T. Hyeon, Prof. D.-H. Kim Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 151-742 , Republic of Korea E-mail: dkim98@snu.ac.kr M. K. Choi, C. Choi, J. Kim, D. J. Lee, M. Kim, W. Hyun, S. J. Kim, Prof. T. Hyeon, Prof. D.-H. Kim School of Chemical and Biological Engineering Institute of Chemical Processes Seoul National University Seoul 151-742 , Republic of Korea O. K. Park, S.-H. Kwon Division of Bio-imaging Korea Basic Science Institute Chun-Cheon 200-701 , Republic of Korea S. Qiao, Prof. N. Lu Center for Mechanics of Solids Structures and Materials Department of Aerospace Engineering and Engineering Mechanics Texas Materials Institute University of Texas at Austin 210 E 24th St , Austin, TX 78712 , USA R. Ghaffari MC10 Inc. 9 Camp St , Cambridge , MA 02140 , USA H. J. Hwang Division of Cardiology Beth Israel Deaconess Medical Center Harvard Medical School , Boston , MA 02215 , USA

Bioresorbable Electronic Stent Integrated with Therapeutic Nanoparticles for Endovascular Diseases

Implantable endovascular devices such as bare metal, drug eluting, and bioresorbable stents have transformed interventional care by providing continuous structural and mechanical support to many peripheral, neural, and coronary arteries affected by blockage. Although effective in achieving immediate restoration of blood flow, the long-term re-endothelialization and inflammation induced by mechanical stents are difficult to diagnose or treat. Here we present nanomaterial designs and integration strategies for the bioresorbable electronic stent with drug-infused functionalized nanoparticles to enable flow sensing, temperature monitoring, data storage, wireless power/data transmission, inflammation suppression, localized drug delivery, and hyperthermia therapy. In vivo and ex vivo animal experiments as well as in vitro cell studies demonstrate the previously unrecognized potential for bioresorbable electronic implants coupled with bioinert therapeutic nanoparticles in the endovascular system.

Multifunctional Cell-Culture Platform for Aligned Cell Sheet Monitoring, Transfer Printing, and Therapy

While several functional platforms for cell culturing have been proposed for cell sheet engineering, a soft integrated system enabling in vitro physiological monitoring of aligned cells prior to their in vivo applications in tissue regeneration has not been reported. Here, we present a multifunctional, soft cell-culture platform equipped with ultrathin stretchable nanomembrane sensors and graphene-nanoribbon cell aligners, whose system modulus is matched with target tissues. This multifunctional platform is capable of aligning plated cells and in situ monitoring of cellular physiological characteristics during proliferation and differentiation. In addition, it is successfully applied as an in vitro muscle-on-a-chip testing platform. Finally, a simple but high-yield transfer printing mechanism is proposed to deliver cell sheets for scaffold-free, localized cell therapy in vivo. The muscle-mimicking stiffness of the platform allows the high-yield transfer printing of multiple cell sheets and results in successful therapies in diseased animal models. Expansion of current results to stem cells will provide unique opportunities for emerging classes of tissue engineering and cell therapy technologies.

Elasticity Solutions to Nonbuckling Serpentine Ribbons

Nanshu Lu Center for Mechanics of Solids, Structures, and Materials, Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, 210 E 24th Street, Austin, TX 78712; Department of Biomedical Engineering, The University of Texas at Austin, 107 W Dean Keeton St., Austin, TX 78712; Texas Materials Institute, The University of Texas at Austin, 204 E. Dean Keeton St., Austin, TX 78712 e-mail: nanshulu@utexas.edu Elasticity Solutions to Nonbuckling Serpentine Ribbons

Stretchable Tattoo-Like Heater with On-Site Temperature Feedback Control

Wearable tissue heaters can play many important roles in the medical field. They may be used for heat therapy, perioperative warming and controlled transdermal drug delivery, among other applications. State-of-the-art heaters are too bulky, rigid, or difficult to control to be able to maintain long-term wearability and safety. Recently, there has been progress in the development of stretchable heaters that may be attached directly to the skin surface, but they often use expensive materials or processes and take significant time to fabricate. Moreover, they lack continuously active, on-site, unobstructive temperature feedback control, which is critical for accommodating the dynamic temperatures required for most medical applications. We have developed, fabricated and tested a cost-effective, large area, ultra-thin and ultra-soft tattoo-like heater that has autonomous proportional-integral-derivative (PID) temperature control. The device comprises a stretchable aluminum heater and a stretchable gold resistance temperature detector (RTD) on a soft medical tape as fabricated using the cost and time effective “cut-and-paste” method. It can be noninvasively laminated onto human skin and can follow skin deformation during flexure without imposing any constraint. We demonstrate the device’s ability to maintain a target temperature typical of medical uses over extended durations of time and to accurately adjust to a new set point in process. The cost of the device is low enough to justify disposable use.

Monolithically integrated stretchable photonics

Mechanically stretchable photonics provides a new geometric degree of freedom for photonic system design and foresees applications ranging from artificial skins to soft wearable electronics. Here we describe the design and experimental realization of the first single-mode stretchable photonic devices. These devices, made of chalcogenide glass and epoxy polymer materials, are monolithically integrated on elastomer substrates. To impart mechanical stretching capability to devices built using these intrinsically brittle materials, our design strategy involves local substrate stiffening to minimize shape deformation of critical photonic components, and interconnecting optical waveguides assuming a meandering Euler spiral geometry to mitigate radiative optical loss. Devices fabricated following such design can sustain 41% nominal tensile strain and 3000 stretching cycles without measurable degradation in optical performance. In addition, we present a rigorous analytical model to quantitatively predict stress-optical coupling behavior in waveguide devices of arbitrary geometry without using a single fitting parameter.

A Thin Elastic Membrane Conformed to a Soft and Rough Substrate Subjected to Stretching/Compression

Nanshu Lu Department of Aerospace Engineering and Engineering Mechanics, Center for Mechanics of Solids, Structures and Materials, The University of Texas at Austin, 210 E. 24th Street, Austin, TX 78712; Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712; Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712; Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712 e-mail: nanshulu@utexas.edu A Thin Elastic Membrane Conformed to a Soft and Rough Substrate Subjected to Stretching/Compression

Conformability of a Thin Elastic Membrane Laminated on a Rigid Substrate With Corrugated Surface

When laminating a thin elastic membrane on a substrate with surface roughness, three scenarios can happen: 1) fully conformed, i.e., the membrane completely follows the surface morphology of the substrate without any interfacial gap; 2) partially conformed; and 3) nonconformed, i.e., the membrane remains flat if gravity is not concerned. Good conformability can enhance effective membrane-to-substrate adhesion and can facilitate heat/signal transfer across the interface, which are of great importance for micromembranes or nanomembranes transferred on target substrates and for flexible electronics laminated on rough biotissues. To reveal the governing parameters in this problem and to predict the conformability, energy minimization method is implemented with two different interfacial models, adhesion energy versus traction-separation relation. Depending on the complexity of the models, one to four dimensionless governing parameters have been identified to analytically predict the conformability status and the point of delamination if partial conformability is expected. In any case, partial conformability is achieved only when membrane energy is considered.