Recent Patents on Nanotechnology - Volume 11, Issue 1, 2017

Background: Nanotechnology has provided significant benefits to photodynamic therapy (PDT), which has revolutionized treatments of several diseases. The success of this versatile technique is governed by the sequential in situ generation of reactive oxygen species, after a suitable photosensitizer has been irradiated by a defined wavelength of light. While PDT provides a minimally-invasive and convenient method for the treatment of several afflictions, the efficiency of this therapeutic strategy still has potential for improvements. Several bodies of works within this realm have highlighted the use of inorganic compounds, which is pivotal for the development of photosensitizers (PSs), nanoparticles (NPs) and irradiation sources. Methods: The past decade of online patented reports based on PDT were reviewed. Results: The patented reports analyzed showcased the integration of nanomaterials and inorganic compounds into PDT. The patents were grouped according to the following categories, viz., “Nanoparticles in Photodynamic Therapy”, “Photosensitizers Incorporating Various Metal Centers”, and “Modifications to Light Delivery”. Conclusion: PDT is a suitable treatment option for several diseases however there are several challenges and limitations. The incorporation of NPs in the field of PDT is an extremely promising avenue which can be utilized to improve the execution of PDT. Furthermore, the use of inorganic compounds was noted to be frequented in the development of PSs and NP conjugates. The patents presented addressed the associated problems with PDT but there still remains an opportunity for continued research efforts so that more clinical applications are possible.

This review focuses on the fundamental fluid mechanics which governs the generation of micro/nanospheres. The micro/nanosphere generation process has gathered significant attention in the past two decades, since micro/nanospheres are widely used in drug delivery, food science, cosmetics, and other application areas. Many methods have been developed based on different operating principles, such as microfluidic methods, electrospray methods, chemical methods, and so forth. This paper focuses on microfluidic methods. Although the structure of the microfluidic devices may be different, the operating principles behind them are often very similar. Following an initial discussion of the fluid mechanics related to the generation of microspheres, various design approaches are discussed, including T-junction, flow focusing, membrane emulsification, modified T-junction, and double emulsification methods. The advantages and problems associated with each method are also discussed. Next, the most commonly used computational fluid dynamics (CFD) methods are reviewed at three different levels: microscopic, mesoscopic, and macroscopic. Finally, the issues identified in the current literature are discussed, and some suggestions are offered regarding the future direction of technology development related to micro/nanosphere generation. Few relevant patents to the topic have been reviewed and cited.

DNA sequencing is one of the crucially important tasks in the fields of genetics and cellular biology, which is benefiting from nanotechnology. DNA carries genetic information and sequencing it in a quick way helps researchers in achieving essential goals, including personalized medicine. Solid state nanopores potentially can offer more durability, in sequencing biomolecules, over the proteinbased nanopores. In recent years, various ideas are introduced towards the goal of fast and low cost sequencing. In this review article recent advances presented in journal articles as well as patents in this field, including sequencing methods, membrane materials and their fabrication techniques, drilling methods, and biomolecule translocation speed control ideas are investigated.

Background: A hydrogen-based Ion-Cut layer-transfer technique, the so-called Ion-Cut or Smart-Cut processing, has been used in transferring a semiconductor membrane onto a desired substrate to reveal unique characteristics on a nanoscale size and to build functional electronic and photonic devices that are used for specific purposes. For example, the sub-100 nm thick silicon membrane transferred onto an insulator became a key substrate for fabricating nanoscale integrated circuit (IC) devices. Recent U.S. patents have exhibited integration of various thinning approaches requiring precision of a few nanometers in fabricating large-area semiconductor nanomembranes, especially for silicon. This paper reviews published patents and work on fabricating sub-100 nm silicon membranes with welldefined features without a chemical-mechanical polishing (CMP) thinning process. This included material analysis leads to ultraprecision thickness in the sub-100 nm region. Methods: This paper combines an analysis of peer-reviewed articles and issued patents using focused review keywords of hydrogen implantation, wafer bonding, and layer splitting. The quality of selected patents was appraised based on the authors’ 20-year research experience in the field of ultrathin silicon layer-transfer technology. Results: The paper covered more than 10 U.S. patents that have been filed on hydrogen-based Ion-Cut layer-transfer techniques. These patents described approaches for inserting hydrogen ions to split at a well-defined location and then transfer the as-split silicon membrane at the nanoscale thickness onto a desired substrate. Hydrogen-trap sites, implantation energy, and interface of the distinct doped regions could define the layer-split location. The insertion of high-dose hydrogen ions could be thoroughly achieved by ion implantation, plasma ion immersion implantation (PIII), plasma diffusion, and electrolysis. Conclusion: The article concludes with the discussion of the patent-orientated review of layer-transfer techniques and makes some concrete suggestions for manufacturing the FDSOI substrate, the key material technology to fabricate nanoscale microelectronics for applications in artificial intelligence for “Industry 4.0.”

Background: The excessive use of fertilizers and pesticides has distorted soil composition, fertility and integrity with non-desirable environmental and ecological consequences. A strategy was designed to prepare a nano structured slow release fertilizer system that delivers nutrients and plant growth promoting rhizobacteria simultaneously. Slow release nano phosphate and potash fertilizer was prepared by blending the nano emulsion of fertilizer with neem cake and PGPR. Slow release nano phosphate and potash fertilizer was prepared by blending the nano emulsion of fertilizer with neem cake and PGPR. Few patents relevant to the topic have been reviewed and cited. Methods: The influence of nano structured slow release fertilizer on the biochemical characteristics, soil and yield attributes of Vigna radiata was studied in the field by randomized block design. The treatments used to evaluate the effect of nano SRF were a control (without any fertilizer), neem cake, chemical fertilizer, PGPR and nano SRF. Germination, specific activity of enzymes, carbohydrates, protein, photosynthetic pigments, root nodule number and microbial population were assessed by standard methods. Results: The size of the nano urea slow release fertilizer ranged from 52.41 nm to 69.86 nm, and the size of the phosphate and potash fertilizer ranged from 81.85 nm to 87 nm. The weights of 1000 grains were 31.8 g, 33.28 g, 33.39 g, 36.65 g and 44.90 g in the control, neem cake, chemical fertilizer, PGPR and nano SRF, respectively. The protein concentrations were 162 mg g-1 in the control, 231 mg g-1 in the neem cake, 192 mg g-1 in the chemical fertilizer, 285 mg g-1 in the PGPR and 336 mg g-1 in the nano SRF. Nano slow release fertilizer treatment has stimulated germination and biochemical characteristics in Vigna radiata that are positively reflected in the yield attributes.

Background: Normal metal mesoscopic rings are being used in designing quantum logical gates due to the quantum interference effect and quantum confinement. This study focused on examining electronic transport through normal metal mesoscopic rings that have one dimension, and suggested how such rings can be employed to design nanoscale AND gate. A double mesoscopic ring was utilized for AND gate operation, every ring was threaded by magnetic flux, and the magnetic flux was considered as the key tuning parameter in the AND gate action. For a particular value of magnetic flux equal to the half of elementary flux-quantum, a logical AND gate operation was used depending on the applied gate voltages. Two gate voltages were externally applied to the lower arm of every ring, which acted as the two inputs of the AND gate. Few relevant patents to the designing and fabrication of quantum logical gates have been reviewed and cited. Methods: All the calculations are based on the time-dependent Hamiltonian model, the steady state is used to obtain the transmission probability. Results: The transmission probability, the current and the noise power of current fluctuations were calculated in the weak-coupling and strong-coupling regimes. Conclusion: This study paved the way for the production of an electronic logic gate.

Background: A theoretical model has been previously proposed to optimize the structure of the electrical probe memory system, whereby the optimal thickness and resistivity of DLC capping layer and TiN under layer are predicted to be 2 nm, 0.01 Ωm, and 40 nm, 2×10-7 Ωm,respectively However, there is no experimental evidence to show that such a media stack can be fabricated in reality by the time of writing and few patents regarding this intriguing topic have been reviewed and cited. Methods: In order to realize this optimized design experimentally, the thickness dependent resistivity for both DLC and TiN film are assessed, from which it is not possible to obtain a media stack with exactly the same properties as the optimized design. Therefore, the previously proposed architecture is re-optimized using the measured properties values, and the capability of using the modified memory architecture to provide ultra-high density, high data rate, and low energy consumption is demonstrated. Results: The results show that it is difficult to experimentally attain an electrical probe memory with exactly the same properties values as the optimized counterpart. Conclusions: An optimized electrical probe memory structure that includes a DLC capping layer and TiN under layer was previously proposed according to a parametric approach, while the practicality of realizing such a media stack experimentally has not bee investigated. In order to assess its practical feasibility, we first measured the electrical resistivities of DLC and TiN films for different thicknesses. In this case, for the purpose of optimizing the memory system with appropriate, but more physically realistic properties values, we re-designed the architecture using the measured properties, and the modified system is able to provide ultra-high density, large data rate, and low energy consumption.

Background: The necessity to handle mechanical functionality at nanoscale has recently motivated the prosperity of the nanoelectromechanical systems (NEMs). The fabrication of NEMS strongly depends on the so-called “topdown” techniques that are however limited by the resolution of electronbeam lithography. Meanwhile, the size of the NEMS needs to be shrunk continuously in order to further enhance the system performance. As a result, current research interest has been dedicated to “bottomup” techniques or even a hybridization of two aforementioned approaches, leading to the presence of the nanowire-based NEMs. Here, we presented some recent patent for nanowire-based NEMS. Methods: We investigate the resonant frequency and the frequency tuneability of the nanowire-based nanoelectromechanical system using Ge2Sb2Te5 media. By varying the nanowire dimensions, corresponding resonant frequencies and frequency tuneability are calculated using an established mechanical model. Results: We theoretically study the frequency tuneability of the nanowire-based NEMs using GST media. The resonant frequencies and the corresponding frequency tuneabilities for different nanowire dimensions are investigated using a developed mechanical model, and a previously established electrothermal model is performed to imitate the frequency tuning behavior of the system along with the phase-change phenomenon. By carefully controlling the amorphous fraction of the active region, a very high resonant frequency can be tuned within an ultra-high adjustable bandwidth. In addition, the merits of the phase-change memories including great scalability, low power consumption, fast transition time, and non-volatility can be also found on the proposed system. These results will open up a route for designing the next generation NEMs, and also pioneer a new application field for the GST media. Conclusions: Today phase-change materials have received a wide range of applications from nonvolatile memories to neuromorphic networks due to its unique combinations of structural, electrical, and thermal properties. However, as the mechanical properties of phase-change materials exhibits a remarkable difference between the amorphous and crystalline phases, the feasibility of continuously changing the resonant frequency of the nanowires based on phase-change materials becomes viable.