Yong Lin Kong

3D Printed Bionic Ears

The ability to three-dimensionally interweave biological tissue with functional electronics could enable the creation of bionic organs possessing enhanced functionalities over their human counterparts. Conventional electronic devices are inherently two-dimensional, preventing seamless multidimensional integration with synthetic biology, as the processes and materials are very different. Here, we present a novel strategy for overcoming these difficulties via additive manufacturing of biological cells with structural and nanoparticle derived electronic elements. As a proof of concept, we generated a bionic ear via 3D printing of a cell-seeded hydrogel matrix in the precise anatomic geometry of a human ear, along with an intertwined conducting polymer consisting of infused silver nanoparticles. This allowed for in vitro culturing of cartilage tissue around an inductive coil antenna in the ear, which subsequently enables readout of inductively-coupled signals from cochlea-shaped electrodes. The printed ear exhibits enhanced auditory sensing for radio frequency reception, and complementary left and right ears can listen to stereo audio music. Overall, our approach suggests a means to intricately merge biologic and nanoelectronic functionalities via 3D printing.

3D Printed Quantum Dot Light-Emitting Diodes

Developing the ability to 3D print various classes of materials possessing distinct properties could enable the freeform generation of active electronics in unique functional, interwoven architectures. Achieving seamless integration of diverse materials with 3D printing is a significant challenge that requires overcoming discrepancies in material properties in addition to ensuring that all the materials are compatible with the 3D printing process. To date, 3D printing has been limited to specific plastics, passive conductors, and a few biological materials. Here, we show that diverse classes of materials can be 3D printed and fully integrated into device components with active properties. Specifically, we demonstrate the seamless interweaving of five different materials, including (1) emissive semiconducting inorganic nanoparticles, (2) an elastomeric matrix, (3) organic polymers as charge transport layers, (4) solid and liquid metal leads, and (5) a UV-adhesive transparent substrate layer. As a proof of concept for demonstrating the integrated functionality of these materials, we 3D printed quantum dot-based light-emitting diodes (QD-LEDs) that exhibit pure and tunable color emission properties. By further incorporating the 3D scanning of surface topologies, we demonstrate the ability to conformally print devices onto curvilinear surfaces, such as contact lenses. Finally, we show that novel architectures that are not easily accessed using standard microfabrication techniques can be constructed, by 3D printing a 2 × 2 × 2 cube of encapsulated LEDs, in which every component of the cube and electronics are 3D printed. Overall, these results suggest that 3D printing is more versatile than has been demonstrated to date and is capable of integrating many distinct classes of materials.

Fermi Surface and Quasiparticle Dynamics of Na0:7CoO2 Investigated by Angle-Resolved Photoemission Spectroscopy

We present the first angle-resolved photoemission study of Na0.7CoO2, the host material of the superconducting NaxCoO2.nH(2)O series. Our results show a hole-type Fermi surface, a strongly renormalized quasiparticle band, a small Fermi velocity, and a large Hubbard U. The quasiparticle band crosses the Fermi level from M toward Gamma suggesting a negative sign of effective single-particle hopping t(eff) (about 10 meV) which is on the order of magnetic exchange coupling J in this system. Quasiparticles are well defined only in the T-linear resistivity (non-Fermi-liquid) regime. Unusually small single-particle hopping and unconventional quasiparticle dynamics may have implications for understanding the phase of matter realized in this new class of a strongly interacting quantum system.

A Scalable Platform for Functional Nanomaterials via Bubble‐Bursting

A continuous and scalable bubbling system to generate functional nanodroplets dispersed in a continuous phase is proposed. Scaling up of this system can be achieved by simply tuning the bubbling parameters. This new and versatile system is capable of encapsulating various functional nanomaterials to form functional nanoemulsions and nanoparticles in one step.

Effect of the Polydispersity of a Colloidal Drop on Drying Induced Stress as Measured by the Buckling of a Floating Sheet.

We study the stress developed during the drying of a colloidal drop of silica nanoparticles. In particular, we use the wrinkling instability of a thin floating sheet to measure the net stress applied by the deposit on the substrate and we focus on the effect of the particle polydispersity. In the case of a bidisperse suspension, we show that a small number of large particles substantially decreases the expected stress, which we interpret as the formation of lower hydrodynamic resistance paths in the porous material. As colloidal suspensions are usually polydisperse, we show for different average particle sizes that the stress is effectively dominated by the larger particles of the distribution and not by the average particle size.

Deposition of Quantum Dots in a Capillary Tube.

The ability to assemble nanomaterials, such as quantum dots, enables the creation of functional devices that present unique optical and electronic properties. For instance, light-emitting diodes with exceptional color purity can be printed via the evaporative-driven assembly of quantum dots. Nevertheless, current studies of the colloidal deposition of quantum dots have been limited to the surfaces of a planar substrate. Here, we investigate the evaporation-driven assembly of quantum dots inside a confined cylindrical geometry. Specifically, we observe distinct deposition patterns, such as banding structures along the length of a capillary tube. Such coating behavior can be influenced by the evaporation speed as well as the concentration of quantum dots. Understanding the factors governing the coating process can provide a means to control the assembly of quantum dots inside a capillary tube, ultimately enabling the creation of novel photonic devices.

Bionic Graphene Nanosensors

The synergistic integration of electronics with biological systems could enable the development of novel sensing devices that could provide new fundamental insights to biomolecular interactions, as well as facilitating the development of novel biointerfaced device architectures. Indeed, the creation of high-performance biomedical sensors with real-time, point-of-care detection could potentially revolutionize the field of early diagnosis and treatment of diseases, improving quality of life. Of particular interest is multitiered interfacing of sensing materials with biology; for example, by coupling the innate selectivity of naturally evolved biomolecules with highly sensitive nanosensors, and subsequently biointerfacing such devices onto the body for real-time detection. This is particularly useful for continual monitoring and diagnosis of complex diseases such as asthma, in which understandings of disease development and the role of environmental triggers are limited. Here, we provide an overview of our specific contributions in: (1) biotransfering graphene sensors onto biological systems to enable a unique bionic nanosensor platform, (2) the detection of bacteria using such platforms via the coupling of antimicrobial peptide bio-recognition molecules to the graphene transducer, (3) the integration of an inductive meander coil with such devices to enable wireless powering and remote readout, (4) the scaling of such devices to wafer-scale arrays using standard microfabrication processing techniques, and (5) the functionalization of these graphene device arrays with a variety of antibodies for ultrasensitive detection of cytokines that are relevant to the detection and diagnosis of asthma from exhaled breath condensate. These results suggest a next-generation “bionic nanosensing” platform that may ultimately promote effective, noninvasive diagnosis and advanced mediation of diseases via early onset detection and continuous tracking of disease progression. Ultimately, large-scale adoption of such systems may enable population pool clinical studies involving dynamic, noninvasive collection of biomarkers for health infrastructure statistical analyses. The graphene bionic nanosensor platform thus represents a powerful new biointerfaced sensing paradigm, with a diverse range of applications.