Development of Voltammetric Double-Polymer-Modified Electrodes for Nanomolar Ion Detection for Environmental and Biological Applications

Qualitative and quantitative electrochemical methods for trace ion analysis of organic and inorganic species with environmental and biological attention have been developed and reported during past decades. The development of fast and accurate electrochemical methods is critical for field applications with various blocking contaminants. Voltammetric method is attractive not only to analyze selective ion species due to its characteristic based on ion lipophilicity, but also to lower the limit of detection by combining with stripping analysis. In my PhD work, I have developed and studied a highly selective and sensitive electrochemical method that can be used to characterize fundamental transport dynamics and to develop electrochemical sensors at liquid/liquid interfaces based on electrochemically-controlled ion transfer and recognition. The understanding of the kinetic and thermodynamic properties of the voltammetric ion transfer through polymer-modified ion-selective electrodes leads to realize the highly selective and sensitive analytical method. The ultrathin polymer membrane is used to maximize a current response by complete exhaustion of preconcentrated ions. Therefore, nanomolar detection is achieved and confirmed by a thermodynamic mechanism that controls the detection limit. It was also demonstrated experimentally and theoretically that more lipophilic ionic species gives a significantly lower detection limit. The voltammetric method was expanded into inexpensive and disposable applications based on pencil lead modified with the thin polymer membrane. In the other hand, micropipet/nanopipet voltammetry as an artificial cell membrane was used to study the interface between two immiscible solutions for environmental and biomedical applications. It is very useful to get quantitative kinetic and thermodynamic information by studying numerical simulations of ion transfer and diffusion. Molecular recognition and transport of heparin and low-molecular-weight heparin drove by hydrophobic receptors were examined thermodynamically and demonstrated that the selectivity for sensor applications is influenced by the interfacial interactions. Also, we found that a new heparin ionophore enables voltammetric extraction of heparins with various average molecular weights

Intensive unilateral neuromuscular training on non-dominant side of low back improves balanced muscle response and spinal stability

Abstract Effective stabilization is important to increase sports performance. Imbalanced spinal muscle responses between the left and right sides increase the risk of spinal buckling and microtrauma at the intervertebral joints. The purpose of this study was to confirm whether intensive unilateral neuromuscular training (IUNT) focusing on the non-dominant side of the low back improves balanced muscle responses and spinal stability. The IUNT group (n = 8) performed side bridge and quadruped exercises using their non-dominant trunk muscles for 8 weeks, while the control group (n = 8) performed their regular training. Before and after the training, motion-capture cameras measured trunk angular displacement, and electromyography recorded the activities of both multifidus muscles (L4-5) during unexpected sudden forward perturbation. After the training in the IUNT group, the difference in onset time between both sides decreased to approximately 120 % compared with that before the training. The asymmetry of muscle activities also decreased from 56 to 23 %. Moreover, the angular displacement on the sagittal plane decreased to approximately 35 % after the training. We expect that IUNT focused on the non-dominant side of the low back will be useful to improve balanced back muscle responses and spinal stability during sudden trunk perturbation

Boundary integral equation method for resonances in gradient index cavities designed by conformal transformation optics

In the case of two-dimensional gradient index cavities designed by the conformal transformation optics, we propose a boundary integral equation method for the calculation of resonant mode functions by employing a fictitious space which is reciprocally equivalent to the physical space. Using the Green's function of the interior region of the uniform index cavity in the fictitious space, resonant mode functions and their far-field distributions in the physical space can be obtained. As a verification, resonant modes in lima\c{c}on-shaped transformation cavities were calculated and mode patterns and far-field intensity distributions were compared with those of the same modes obtained from the finite element method.Comment: 13 pages, 6 figure

Roll-to-roll gravure printed smart food package to replace the "use-by" date system of foods

The implementation of internet of things (IoT) to the food industry offers a great deal, accompanying each functional unit from production to the consumption to ensure the quality of a particular food item. Among several factors, the fluctuation in temperature through the cold chain are prone to the propagation of foodborne pathogens and is considered as a leading factor to reduce the shelf life. Therefore, a smart food package, which dynamically monitors the time-temperature history (TTH) throughout the food logistics will be very crucial to access meaningful data regarding the quality and safety of a food package. This smart packaging system utilizing NFC function of the smartphone to access quality information of a food item not only prevents from the blind disposal of consumable items if the quality is good enough to consume but also prohibits the consumers from its usage if the quality is bad, which at present is heavily relied upon the due date. However, the cost issue associated with the manufacturing of radio frequency identification (RFID) prohibits these systems from implementing to a smart packaging system for everyday consumable food products. To resolve this, we incorporated fully scalable, high throughput, and flexible roll-to-roll (R2R) gravure printing system to realize the NFC antenna, flexible printed circuit board (FPCB), a thermistor, and a battery. We successfully demonstrate the printing of NFC antenna as well as the thermistor continuously from the two printing units at a practical printing speed of more than 6 m/min on a polyimide (PI) substrate. The printing conditions such as nip-roll pressure, blade angle was optimized to 6 kgf and 9°, respectively to ensure the quality printing of both antenna and the thermistor, whereas the viscosity of the silver nanoparticle ink for realizing antenna was 1000 cP. The Si-chip transponder was embedded to the printed NFC tag, by using a daughter board, to record the temperature at custom-defined time instants throughout the cold chain

Photonic curing for enhancing the performance of roll-to-roll printed electronic devices

The advent in printing technology promotes the possibility of roll-to-roll manufacturing process for low-cost, high throughput, and large area printing of the electronic devices in flexible substrate materials. However, the conductivity of the nanoparticle ink being utilized for printing process is the major challenge to compete with the existing silicon-based technology in terms of the device performance. A number of post-processing steps were proposed over the year to enhance the conductivity and among them thermal curing is the easiest solution so far. However, in high speed R2R processing system, thermal curing is not compatible owing to its long curing time or high temperature required to attain the desired conductivity. To overcome the issues of thermal curing, Intense Pulsed Light (IPL) photonic sintering has shown a promising capability to sinter the printed conducting patterns in milliseconds. Furthermore, photonic sintering can either be embedded together with R2R system during printing or in conjunction with the thermal curing is viewed as a viable approach to improve the conductivity of printed pattern. In this work, we studied different photonic sintering techniques and compared the results with the conventional thermal curing methodology in R2R printed near-field communication (NFC) antenna patterns. Experimental results showed that photonic sintering can reduce the resistance of the antenna more effectively than thermal curing even on polyethylene terephthalate (PET) with low melting point. The limitations of the present sintering techniques were highlighted from the prospect of future enhancement

Interaction of Hydrogen with Graphitic Surfaces, Clean and Doped with Metal Clusters

Producción CientíficaHydrogen is viewed as a possible alternative to the fossil fuels in transportation. The technology of fuel-cell engines is fully developed, and the outstanding remaining problem is the storage of hydrogen in the vehicle. Porous materials, in which hydrogen is adsorbed on the pore walls, and in particular nanoporous carbons, have been investigated as potential onboard containers. Furthermore, metallic nanoparticles embedded in porous carbons catalyze the dissociation of hydrogen in the anode of the fuel cells. For these reasons the interaction of hydrogen with the surfaces of carbon materials is a topic of high technological interest. Computational modeling and the density functional formalism (DFT) are helping in the task of discovering the basic mechanisms of the interaction of hydrogen with clean and doped carbon surfaces. Planar and curved graphene provide good models for the walls of porous carbons. We first review work on the interaction of molecular and atomic hydrogen with graphene and graphene nanoribbons, and next we address the effects due to the presence of metal clusters on the surface because of the evidence of their role in enhancing hydrogen storage.Ministerio de Economía, Industria y Competitividad (Grant MAT2014-54378-R

Kilohertz-frequency interferential current induces hypoalgesic effects more comfortably than TENS

Abstract Recent research on transcutaneous electrical stimulation has shown that inhibiting nerve conduction with a kilohertz frequency is both effective and safe. This study primarily aims to demonstrate the hypoalgesic effect on the tibial nerve using transcutaneous interferential-current nerve inhibition (TINI), which injects the kilohertz frequency produced by the interferential currents. Additionally, the secondary objective was to compare the analgesic effect and comfort of TINI and transcutaneous electrical nerve stimulation (TENS). Thirty-one healthy adults participated in this cross-over repeated measures study. The washout period was set to 24 h or more. Stimulus intensity was set just below the pain threshold level. TINI and TENS were applied for 20 min each. The ankle passive dorsiflexion range of motion, pressure pain threshold (PPT), and tactile threshold were measured at the baseline, pre-test, test (immediately before ceasing intervention), and post-test (30 min after ceasing intervention) sessions. After the interventions, the participants evaluated the level of discomfort for TINI and TENS on a 10 cm visual analog scale (VAS). As the results, PPT significantly increased compared to baseline in test and posttest sessions of TINI, but not in those of TENS. Also, participants reported that TENS was 36% more discomfort than TINI. The hypoalgesic effect was not significantly different between TINI and TENS. In conclusion, we found that TINI inhibited mechanical pain sensitivity and that the inhibitory effect persisted long after electrical stimulation ceased. Our study also shows that TINI provides the hypoalgesic effect more comfortably than TENS

Searchable Blockchain-Based Healthcare Information Exchange System to Enhance Privacy Preserving and Data Usability

Ensuring the security and usability of electronic health records (EHRs) is important in health information exchange (HIE) systems that handle healthcare records. This study addressed the need to balance privacy preserving and data usability in blockchain-based HIE systems. We propose a searchable blockchain-based HIE system that enhances privacy preserving while improving data usability. The proposed methodology includes users collecting healthcare information (HI) from various Internet of Medical Things (IoMT) devices and compiling this information into EHR blocks for sharing on a blockchain network. This approach allows participants to search and utilize specific health data within the blockchain effectively. The results demonstrate that the proposed system mitigates the issues of traditional HIE systems by providing secure and user-friendly access to EHRs. The proposed searchable blockchain-based HIE system resolves the trade-off dilemma in HIE by achieving a balance between security and the data usability of EHRs