Lanlin Zhang

Bio: Lanlin Zhang is an academic researcher from Ohio State University. The author has contributed to research in topics: Antenna (radio) & Microstrip antenna. The author has an hindex of 13, co-authored 32 publications receiving 640 citations. Previous affiliations of Lanlin Zhang include John L. Scott.

Embroidered Conductive Fibers on Polymer Composite for Conformal Antennas

Abstract: We provide a novel class of conformal antennas based on embroidered conductive metal-polymer fibers (E-fiber) on polymer-ceramic composites. This new technology offers attractive mechanical and RF performance when compared to traditional flat and rigid circuits and antennas. The proposed E-fiber components are consisted of high strength and flexible polymer fiber cores and conductive metallic coatings. They were fabricated using automatic embroidery process, followed by assembly with polydimethylsiloxane and rare-earth titanate ceramic composites. Such composite substrates were tape-casted, and capable of providing tunable dielectric constant from 3 to 12 with a low tanδ <; 10-2 up to GHz frequencies. Basic RF prototypes, such as transmission lines (TL), patch antennas, and antenna arrays were fabricated for experimental evaluation. Measurement of the prototypes were conducted and compared to their copper counterparts. The RF characteristics of the E-fiber TLs exhibited an insertion loss of only 0.03 dB/cm higher than copper TLs up to 4 GHz . Also, the E-fiber patch antenna and antenna array exhibited 0.3 dB and 0.6 dB lower gains, respectively, than their copper counterparts. When applied onto a cylindrical surface, both the E-fiber patch antenna and antenna array only suffered 1 dB loss in realized gain, which is quite remarkable when compared with traditional antennas.

Textile Antennas and Sensors for Body-Worn Applications

Abstract: This letter presents novel body-worn antennas and medical sensors based on embroidered conductive polymer fibers (e-fibers) on textiles. This technology offers attractive mechanical and RF performance when compared to traditionally flat and rigid antennas and circuits. The e-fibers are composed of high-strength and flexible polymer cores that incorporate conductive metallic coatings. They are readily embroidered onto regular textiles and can also be laminated on to polymer dielectric substrates. The RF characteristics of the e-fiber textiles were evaluated using microstrip transmission line (TL) structures. They exhibited an insertion loss of only 0.07 dB/cm at 1 GHz and 0.15 dB/cm at 2 GHz. Prototype body-worn multiband/wideband antennas and medical sensor were constructed to demonstrate their efficiency and comparable performance to that of copper. All designs were fabricated with high precision and resolution down to 0.5 mm.

Experimental Validation of Frozen Modes Guided on Printed Coupled Transmission Lines

Abstract: Previous work has theoretically demonstrated that nonreciprocal slow-wave modes, namely, “frozen modes,” can be supported on a pair of coupled transmission lines printed on a magnetic substrate. Small antennas have also been designed by exploiting these modes. However, to date, we have yet to demonstrate and observe their existence experimentally. To this end, we construct two printed prototypes comprised of several unit-cells and employ the “T-matrix method” to determine the dispersion properties by measuring the S-parameters of these finite periodic prototypes. The printed unit-cell is designed to exhibit a unique stationary inflection point in the dispersion diagram corresponding to a frozen mode with almost zero group velocity. Through careful measurements and calculations, the frozen mode is observed to propagate at a significantly slower speed (286 times slower) than the speed of light. Importantly, this extraction method can be applied to any other periodic layout to obtain related dispersion properties.

Flexible textile antennas for body-worn communication

Abstract: This paper presents an embroidered body-worn antenna using conductive fibers (E-fibers). The antenna's conductive surfaces were fabricated using precise and automated embroidering techniques to produce fully flexible and conformal antenna elements attached to regular fabrics and clothing. These E-fiber antennas offer desirable mechanical properties without undermining electrical performance for body-worn, on-clothing applications at radio frequencies (RF). In this study, we used an embroidered asymmetric meandered flare (AMF) dipole antenna to validate the textile antenna's performance. Its excellent RF performance was found comparable to conventional printed antennas. Therefore, these new E-fiber antennas may be integrated into scarves, handbags, shirts, coats or hand bands for convenient carefree health monitoring and wideband communications.

Supported inorganic membranes: Promises and challenges

Abstract: Supported inorganic membranes hold the promise of highly effective separation and purification, and stable operation in harsh environments. Examples are thin films of paladium alloy for H2, mixed conducting oxides for O2, amorphous silica for CO2 and zeolites for hydro-carbons, and meso-porous titania for water purification. However, compared to organic membranes, large-scale production of inorganic membranes requires improvements in reproducibility and cost processes. This short overview provides terminology, concepts, and important criteria for performance, stability, reproducibility, and cost of supported inorganic membranes. Also discussed are possible approaches to address the challenges, and examples for designing gas separation and water purification.

Carbon Dioxide Capture: Prospects for New Materials

Abstract: The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

Abstract: Fiber-based structures are highly desirable for wearable electronics that are expected to be light-weight, long-lasting, flexible, and conformable Many fibrous structures have been manufactured by well-established lost-effective textile processing technologies, normally at ambient conditions The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns However, imparting electronic functions to porous, highly deformable and three-dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation This article attempts to critically review the current state-of-arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber-based wearable electronic products In addition, this review elaborates the performance requirements of the fiber-based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber-based electronic devices Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption

Wearable Electronics and Smart Textiles: A Critical Review

Abstract: Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible of becoming tangled or snagged by surrounding objects. E-textiles can also more easily adapt to fast changes in the computational and sensing requirements of any specific application, this one representing a useful feature for power management and context awareness. The vision behind wearable computing foresees future electronic systems to be an integral part of our everyday outfits. Such electronic devices have to meet special requirements concerning wearability. Wearable systems will be characterized by their ability to automatically recognize the activity and the behavioral status of their own user as well as of the situation around her/him, and to use this information to adjust the systems' configuration and functionality. This review focuses on recent advances in the field of Smart Textiles and pays particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and our aim is to highlight a possible trade-off between flexibility, ergonomics, low power consumption, integration and eventually autonomy.

Ag Nanowire Reinforced Highly Stretchable Conductive Fibers for Wearable Electronics

Abstract: Stretchable conductive fi bers have received signifi cant attention due to their possibility of being utilized in wearable and foldable electronics. Here, highly stretchable conductive fi ber composed of silver nanowires (AgNWs) and silver nanoparticles (AgNPs) embedded in a styrene‐butadiene‐styrene (SBS) elastomeric matrix is fabricated. An AgNW-embedded SBS fi ber is fabricated by a simple wet spinning method. Then, the AgNPs are formed on both the surface and inner region of the AgNW-embedded fi ber via repeated cycles of silver precursor absorption and reduction processes. The AgNW-embedded conductive fi ber exhibits superior initial electrical conductivity ( σ 0 = 2450 S cm −1 ) and elongation at break (900% strain) due to the high weight percentage of the conductive fi llers and the use of a highly stretchable SBS elastomer matrix. During the stretching, the embedded AgNWs act as conducting bridges between AgNPs, resulting in the preservation of electrical conductivity under high strain (the rate of conductivity degradation, σ / σ 0 = 4.4% at 100% strain). The AgNW-embedded conductive fi bers show the strain-sensing behavior with a broad range of applied tensile strain. The AgNW reinforced highly stretchable conductive fi bers can be embedded into a smart glove for detecting sign language by integrating fi ve composite fi bers in the glove, which can successfully perceive human motions.