NanoLab (United States)

Ionic liquid/ionogel gate dielectrics can provide significant advantages for transistor architectures that utilize high surface area semiconductors and/or nonplanar substrates because of their cleanroom-free, liquid-based processability and their inherently large electrostatic double layer capacitance. These attributes of ionogels have already enabled the facile fabrication of several up-and-coming transistor devices geometries for which a highly conformal interface between the electrolyte gate dielectric and the semiconductor is readily achievable, and remote gating with a nonaligned gate electrode is possible. Further, ionogel gating can improve device performance to maximize current densities at low operating voltages. This Perspective highlights three classes of emerging transistor architectures, namely, vertical transistors, surround gate transistors, and thread/fiber-based transistors, and provides several key examples of instances where ionogel gating has either already enabled or still stands to improve device fabrication and performance.

A new SILP (Supported Ionic Liquid Phase) palladium catalyst was prepared and characterized by 13C and 29Si CP MAS NMR, DTG, FTIR and TEM. The presence of the grafted pyridinium cations on the surface of the support was found to result in the formation of highly dispersed Pd nanoparticles with their diameter in the range of 1–2 nm. The catalyst was proved to be active not only in the aminocarbonylation of some model compounds but also in the synthesis of active pharmaceutical ingredients. Catalyst recycling and palladium leaching studies were carried out for the first time in aminocarbonylations leading to CX-546(1-(1,4-benzodioxan-6-ylcarbonyl)piperidine), Moclobemide, Nikethamide and a precursor of Finasteride. The latter reaction proves that not only aryl iodides but also an iodoalkene can be converted into the products with the help of the heterogeneous catalyst. The results show that the conditions should be always fine-tuned in the reactions of different substrates to achieve optimal results. Palladium loss was also observed to depend considerably on the nature of the reaction partners.

We present washable smart sensing threads for creation of smart wearable fabrics. More specifically, we report the fabrication of a facile stretchable and washable thread-based strain/force sensor, which can be sewn into wearable textiles and is capable of measuring human physiological motion. We use polybutylene terephthalate (PBT) puffy threads as our substrate which is made strain-sensitive using a simple reel-to-reel coating process. While PBT in itself is not very stretchable, threads made from them have coiled helical filaments. Stretching such threads uncoils these filaments imparting them stretchability. To convert them into strain sensor, we coat these PBT threads with resistive carbon ink. The straightening (uncoiling) of the helical filaments changes its resistance. There is a negligible change in resistance after repeated washing steps. Such washable immunity is achieved by coating thin layer of PDMS on them. The sensor exhibits a constant gauge factor of ~2.5 within its working range (50% strain) and exhibits a linear response to applied strain up to 50% of its initial length. Such strain sensing threads can form the basis of smart fabrics that can track human motion and for use in real-time physiological monitoring. We present promising results on the detection of the human form (seated versus standing) and human motion (running versus walking) using these threads sewn onto trousers.

Vertically aligned carbon nanotube arrays are world renowned for their excellent optical absorption properties. However, at low angles, they suffer from higher reflection coefficients, due to the aligned structure. NanoLab has researched the potential for carbon nanotube loaded paints, (now marketed as Singularity Black) to create a more randomized structure with high optical and infrared absorption that will have better grazing angle performance. Other drivers for the development of a paint version include the desire to apply these coatings in large areas, on lower temperature substrates, and at lower cost. This paper describes the structures necessary for highly absorbing black coatings, and reviews the approach and data collected for two products, Singularity Black paint and the vertically aligned nanotube coating adVANTA.

The ever increasing demand for bandwidth in wireless communication systems will inevitably lead to the extension of operating frequencies toward the terahertz (THz) band known as the 'THz gap'. Towards closing this gap, we present a multi-level amplitude shift keying (ASK) terahertz wireless communication system using terahertz spatial light modulators (SLM) instead of traditional voltage mode modulation, achieving higher spectral efficiency for high speed communication. The fundamental principle behind this higher efficiency is the conversion of a noisy voltage domain signal to a noise-free binary spatial pattern for effective amplitude modulation of a free-space THz carrier wave. Spatial modulation is achieved using an an active metamaterial array embedded with pseudomorphic high-electron mobility (pHEMT) designed in a consumer-grade galium-arsenide (GaAs) integrated circuit process which enables electronic control of its THz transmissivity. Each array is assembled as individually controllable tiles for transmissive terahertz spatial modulation. Using the experimental data from our metamaterial based modulator, we show that a four-level ASK digital communication system has two orders of magnitude improvement in symbol error rate (SER) for a degradation of 20 dB in transmit signal-to-noise ratio (SNR) using spatial light modulation compared to voltage controlled modulation.

Hydrogels, formed through cross-linking of hydrophilic polymer chains, represent a class of materials that are capable of holding large volumes of water. Here we report a novel class of hydrophobic hydrogels that can free-float on the surface of different aqueous media by coating conventional hydrogels with a layer of hydrophobic microparticles. We further demonstrate that these floating hydrogel-based devices can be used for sensing applications on liquid surfaces such as the construction of floating pH meters. Moreover, we demonstrate that the floating hydrogels present high mobility with excellent self-assembling property on the surface of water. Importantly, the floating systems reserved the intrinsic biocompatibility of the core hydrogels, enabling microengineering of floating tissue constructs. It is expected that these floating hydrophobic hydrogel-based devices will likely find widespread applications including but not limited to sensing, tissue engineering, and biomedicine.

In this paper, we present a single-bit clock-less asynchronous delta–sigma modulator (ADSM) operating at just 0.25 V power supply. Several circuit approaches were employed to enable such low-voltage operation and maintain high performance. One approach involved utilizing bulk-driven transistors in subthreshold region with transconductance-enhancement topology. Another approach was to employ distributed transistor layout structure to mitigate the effect of low output impedance due to halo drain implants employed in today’s digital CMOS process. The ADSM achieved a characteristic center frequency of 630 Hz. It had an effective signal-to-noise-plus-distortion ratio (SNDR) of 58 dB or effective number of bits (ENOB) 9 b and just 28-nW power dissipation. A detailed analytical model capturing the effect of nonidealities of the individual circuit components is also presented for the first time with a close agreement with experimental results.

We present a microfluidic optoelectronic sensor for detection of dissolved CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in aqueous samples. The sensor contains an array of wells embedded in a microfluidic device and filled with ion-exchange polymeric microbeads doped with halocromic dyes. We have developed a simple procedure for microbeads deposition that allows incorporation of virtually any combination of halocromic dyes, providing a route for cross-reactive sensing. Due to a versatile optical arrangement, using LEDs and photodiodes, optical signals are easily translated into electronic readouts. We demonstrate the sensor ability to provide distinct responses to different concentrations of dissolved CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Moreover, the sensor shows no cross sensitivity to acidity not related to dissolved CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .

We embed diodes as active circuit elements within a metamaterial to implement a switchable metamaterial reflector/absorber at microwave frequencies. Diodes are placed in series with the unit cells of the metamaterial array. This results in just a pair of control lines to actively tune all the diodes in a metamaterial. Diodes can be tuned on and off to switch the function of the metamaterial between a perfect absorber and a reflector. The design, simulation, and experimental results of a switchable reflector/absorber in 2–6 GHz range are presented.