Fanben Meng

Orthogonally modulated molecular transport junctions for resettable electronic logic gates

Individual molecules have been demonstrated to exhibit promising applications as functional components in the fabrication of computing nanocircuits. Based on their advantage in chemical tailorability, many molecular devices with advanced electronic functions have been developed, which can be further modulated by the introduction of external stimuli. Here, orthogonally modulated molecular transport junctions are achieved via chemically fabricated nanogaps functionalized with dithienylethene units bearing organometallic ruthenium fragments. The addressable and stepwise control of molecular isomerization can be repeatedly and reversibly completed with a judicious use of the orthogonal optical and electrochemical stimuli to reach the controllable switching of conductivity between two distinct states. These photo-/electro-cooperative nanodevices can be applied as resettable electronic logic gates for Boolean computing, such as a two-input OR and a three-input AND-OR. The proof-of-concept of such logic gates demonstrates the possibility to develop multifunctional molecular devices by rational chemical design.

Sericin for resistance switching device with multilevel nonvolatile memory.

Resistance switching characteristics of natural sericin protein film is demonstrated for nonvolatile memory application for the first time. Excellent memory characteristics with a resistance OFF/ON ratio larger than 10(6) have been obtained and a multilevel memory based on sericin has been achieved. The environmentally friendly high performance biomaterial based memory devices may hold a place in the future of electronic device development.

Electrochemical Approach To Detect Apoptosis

This paper reports an electrochemical approach for detection of apoptosis. Here we prepare a gold electrode modified with a helix peptide ferrocene (Fc)-GDGDEVDGC. Fc is used as an electroactive reporter and the peptide as a recognition and cleavage site of caspase-3, which is a special proteinase to apoptosis. Results show that this method may sensitively and specifically detect apoptotic cells with signal decline of 85%. This approach is different from the previous methods for apoptosis detection, because it does not need any fluorescent materials, expensive biological instruments, or complicated procedures.

Resistive Switching Memory Devices Based on Proteins

Resistive switching memory constitutes a prospective candidate for next-generation data storage devices. Meanwhile, naturally occurring biomaterials are promising building blocks for a new generation of environmentally friendly, biocompatible, and biodegradable electronic devices. Recent progress in using proteins to construct resistive switching memory devices is highlighted. The protein materials selection, device engineering, and mechanism of such protein-based resistive switching memory are discussed in detail. Finally, the critical challenges associated with protein-based resistive switching memory devices are presented, as well as insights into the future development of resistive switching memory based on natural biomaterials.

Visible Photoresponse of Single‐Layer Graphene Decorated with TiO2 Nanoparticles

Graphene has garnered enormous attention due to the gamut of its unique properties such as wavelength-independent light absorption and high operating bandwidth, paving the way for applications in photonics and optoelectronics in various forms such as light-emitting devices, solar cells and photodetectors. [ 1 ] However, limitations of pristine graphene have come to light recently, [ 2 ] and two chief problems can be attributed to the low photoresponse of pristine graphene. Firstly, single layer graphene absorbs merely ∼ 2.3% of incident light and has a strong interation with light only in the far-IR region [ 3 ]

Protein-Based Memristive Nanodevices

6 Memristors (memory resistors), represent the fourth fundamental two-terminal circuit element following the resistor, the capacitor, and the inductor. [ 1 , 2 ] Memristors have attracted much attention owing to their potential application in nanoelectronic memories, computer logic, neuromorphic computer architectures, and so on. [ 3–6 ] Williams et al. were the fi rst to demonstrate a solid-state memristive device based on a titanium dioxide thin fi lm, which was inserted between two Pt electrodes. [ 2 ] Thus far, various materials such as metal oxides, [ 7–10 ] chalcogenides, [ 11 ] amorphous silicon, [ 12–15 ] or carbon, [ 16 ] as well as polymer–nanoparticle composite materials [ 17 ] have been demonstrated to exhibit memristive phenomena. Many activities in life exhibit memory behavior. Substantial research has focused on biomolecules serving as computing elements, [ 18–20 ] and as such natural biomaterials may have the potential to be exploited as electronic memristors. Some types of proteins, especially redox proteins, have been shown to act as electronic materials when inserted between electrodes to achieve solid-state electron-transport junctions. [ 21–23 ] In this communication, protein-based bipolar memristive nanodevices in which proteins are embedded into the nanogaps are demonstrated. Several methods, such as mechanical break-junction techniques, [ 24 , 25 ] electromigration, [ 26–28 ] and shadow mask evaporation [ 29–31 ] have all been used to fabricate nanogaps; nanostructures that have metal-electrode pairs separated by a few nanometers that enable an electrical contact to target molecules. On-wire lithography (OWL), a chemistry-based nanofabrication technique, is a high-throughput method used to prepare nanogaps, affording control of feature sizes down to typical molecular dimensions. [ 32 , 33 ] This method relies on the template-directed synthesis of nanowires in an anodized aluminum oxide membrane by the electrochemical deposition of desired metal materials. The gap size is controlled by the thickness of a thin sacrifi cial layer of Ni,

3D Printed Stretchable Tactile Sensors

The development of methods for the 3D printing of multifunctional devices could impact areas ranging from wearable electronics and energy harvesting devices to smart prosthetics and human-machine interfaces. Recently, the development of stretchable electronic devices has accelerated, concomitant with advances in functional materials and fabrication processes. In particular, novel strategies have been developed to enable the intimate biointegration of wearable electronic devices with human skin in ways that bypass the mechanical and thermal restrictions of traditional microfabrication technologies. Here, a multimaterial, multiscale, and multifunctional 3D printing approach is employed to fabricate 3D tactile sensors under ambient conditions conformally onto freeform surfaces. The customized sensor is demonstrated with the capabilities of detecting and differentiating human movements, including pulse monitoring and finger motions. The custom 3D printing of functional materials and devices opens new routes for the biointegration of various sensors in wearable electronics systems, and toward advanced bionic skin applications.

Bioengineered Tunable Memristor Based on Protein Nanocage

Bioengineered protein-based nanodevices with tunable and reproducible memristive performance are fabricated by combining the unique high loading capacity of Archaeoglobus fulgidus ferritin with OWL-generated nanogaps. By tuning the iron amount inside ferritin, the ON/OFF ratio of conductance switching can be modulated accordingly. Higher molecular loading exhibits better memristive performance owing to the higher electrochemical activity of the ferric complex core.

Enhanced Photoresponse of Conductive Polymer Nanowires Embedded with Au Nanoparticles

A conductive polymer nanowire embedded with a 1D Au nanoparticle chain with defined size, shape, and interparticle distance is fabricated which demonstrates enhanced photoresponse behavior. The precise and controllable positioning of 1D Au nanoparticle chain in the conductive polymer nanowire plays a critical role in modulating the photoresponse behavior by excitation light wavelength or power due to the coupled-plasmon effect of 1D Au nanoparticle chain.

Gold nanotip array for ultrasensitive electrochemical sensing and spectroscopic monitoring.

A gold nanotip array platform with a combination of ultrasensitive electrochemical sensing and spectroscopic monitoring capability is reported. Adenosine triphosphate is detected down to 1 pM according to the impedance changes in response to aptamer-specific binding. Furthermore, the local molecular information can be monitored at the individual plasmonic nanotips, and hence provide the capability for a better understanding of complex biological processes.