Passive Patches Research Articles

Position Optimization of Passive Patch Based on Mode Contribution Factor for Vibration Attenuation of Asymmetric 1D Structure

When the thickness of a structure is reduced to decrease weight, it may experience structural vibration and disturbance. The use of passive patches is effective in addressing this issue when the loss factor is small or when space and weight are restricted. The greatest attenuation occurs when passive patches are used across the entire coverage area. However, passive patches of reasonable size must be affixed to ensure that they are effective in terms of cost and design. In this paper, the sum of squares’ value for the bending mode shape is used to determine the location of a small passive patch to achieve vibration damping for multiple modes. Under the condition of forced vibration, the modal contribution of each mode is obtained. Using this contribution as a weight, the optimal position of the passive patch is determined as the maximum value obtained in the form of a linear combination multiplied by the curvature of the beam. Simulation and experiment were used to test the efficacy of the location determined for passive patches. It was determined that, depending on the location of the passive patch, the peak amplitude at the natural frequency of each mode decreased significantly, validating the effectiveness of the design method.

Internet-of-Things-Enabled Dual-Channel Iontophoretic Drug Delivery System for Elderly Patient Medication Management.

Wireless controllers have found its application in the supervision of the patients in the hospitals. It is not only a valid issue for the developing countries but also for the developed countries. For this reason, scientists are working on the advancement of medical devices that are capable of decreasing the workload of health caregivers. In this study, the development of an iontophoretic drug delivery device that could be controlled using a mobile is described. For the purpose, hardware and a software module were developed. The hardware module consisted of a two-channel voltage-controlled constant current sources that were used for driving the iontophoretic device. A mobile app was developed to control the two-channel iontophoretic device and to monitor the loose lead of the active and the passive patches. In the case of detection of the loose lead, the specific iontophoretic channel was stopped. Further, the audio-visual indicator was developed for the detection of the detachment of the patches (loose lead). The device was tested in vitro by performing the drug release study using drug-loaded emulsion gels that were formulated.

Controllable and re‐usable patch for transdermal iontophoresis drug delivery

Transdermal active drug delivery is one way to propose new disease treatment as an improvement to passive patches diffusion based on concentration gradient. Although skin limitations due to low permeability active transdermal delivery approach are investigated, by the proposition of an iontophoretic reusable and controllable patch. Making such an e-health care device offers active control and permanent actuating link able to control the amount of drug delivered. In vitro experiment is conducted to investigate the current effect on the permeation. Modelling and simulations are carried out to optimise the design and the electrical stimulation and finally a global overview of the architecture of the patch is presented.

Beam steering patch antenna using reactive loading and Yagi‐antenna concept

ABSTRACTThis letter reports a technique to create beam‐steering antennas using reactive loading and passive patches. In this antenna configuration, the center patch is fed by a microstrip line and the two neighbor patches are excited through the mutual coupling from the active antenna. These two patches are loaded with a varactor diode and present a phase shift that depends on varactor capacitance. The impact of the mutual coupling on the impedance matching is investigated through a numerical calculation that combines 3D full‐wave simulation and network analysis formulas. The steering capability is enhanced by adding “director” passive patches as in the Yagi antenna principle. A prototype is designed, fabricated, and measured at UHF frequency (865–868 MHz) and shows a good agreement with the simulation. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:417–421, 2015

A Review of Active Blade Twist Technology: Part II – Integral Twist Actuation

Marques P. (2014). A review of active blade twist technology: Part II – Integral twist actuation. International Journal of Unmanned Systems Engineering. 2(S2): 26-36. This paper evaluates integral actuation concepts and rotor optimisation for the design of advanced rotor-UAVs (RUAVs). Design and optimization of adaptive helicopter rotor blades requires an interdisciplinary approach that incorporates structural mechanics, aerodynamics, rotor dynamics, actuator technology, power-electronics and control. Advances in active materials allow integral embedding of actuators on the load bearing blade structure and offer redundancy in operation and reduced profile drag. Single crystal piezoelectric fiber composites yield strain levels five times larger than those of conventional piezoceramics and efficiently reduce the vibration and acoustic signal of helicopters. The SHARCS (Smart Hybrid Active Rotor Control System) project demonstrates simultaneous reduction of vibration and noise on helicopters using a hybrid system that integrates three independent active control systems. Active Pitch Link and Actively Controlled Flap primarily reduce vibration, whereas Actively Controlled Tip reduces noise. The Smart Spring acts as a mechanical filter that attenuates the higher harmonic vibratory loads. Active vibration damping is efficient for harmonic excitation and passive piezoelectric patches are suitable for the suppression of the large spectrum oscillations caused by impulse load. An actively controlled Hiller type servopaddle achieves helicopter rotor control using a swashplateless configuration. Optimization of active twist blades is a complex task that involves a highly non-linear design space with tightly coupled variables. Rotor blade optimisation is becoming an increasingly important part of the design process as engineers push further the boundaries of helicopter aerodynamic efficiency and performance. Recent optimization work included CFD combined with meta-models, artificial neural networks, kriging interpolation, and a non-gradient based optimiser using genetic algorithms. Integral actuation technologies and optimisation methods should be incorporated in advanced RUAV concepts. © Marques Engineering Ltd.

Subcutaneous concentrations following topical iontophoretic delivery of diclofenac

A self-contained Wearable Electronic Disposable Drug Delivery (WEDD(®)) patch was used to demonstrate that diclofenac levels delivered by iontophoresis are greater than estimated minimal effective concentrations in local subcutaneous tissue and are also greater than either passive transdermal or intravenous delivery using hairless rats. In vitro iontophoretic delivery was evaluated to optimize donor cell formulation using Franz diffusion cells and 1000 NMWL Millipore ultrafiltration membrane. In vivo animal studies were done using patches powered with a 4-volt system, consisting of a 1-volt Zn anode and Ag/AgCl cathode with built in 3-volt lithium battery. Blood and microdialysis samples were collected at different time points after patch application. Current levels increased to 1.0 mA at 30 min, then fell to a steady state of ~ 0.4 mA. Both WEDD(®) and passive patches produced measurable levels of diclofenac in the subcutaneous tissue below the application site (C(max) ± SE = 113.3 ± 61.7 ng/mL and 36.3 ± 15.9 ng/mL, respectively). The dose delivered in six hours was calculated to be 0.226 ± 0.072 mg and 0.430 ± 0.048 mg in passive and iontophoretic delivery, respectively. Diclofenac was not detected in the subcutaneous tissue after intravenous administration of 1.5 mg/kg diclofenac solution. The trend indicates that WEDD(®) can be used to successfully deliver diclofenac to subcutaneous tissue to concentrations higher when compared to either passive delivery or intravenous dosing of 1.5 mg/kg.

Investigation of drug delivery by iontophoresis in a surgical wound utilizing microdialysis.

This study investigated the penetration of lidocaine around and through a sutured incision following the application of iontophoretic and passive patches in the CD Hairless rat. Concentrations in localized areas (suture, dermis, subcutaneous, and vascular) were determined using microdialysis sampling followed by analysis using liquid chromatography with UV detection. Iontophoresis significantly enhanced the dermal penetration of lidocaine. In an intact skin model, dermal concentrations were 40 times greater following iontophoretic delivery compared to passive delivery. In a sutured incision model, iontophoresis enhanced localized concentrations in the dermis, suture, and subcutaneous regions by 6-, 15-, and 20-fold, respectively. Iontophoretic delivery to a region containing a sutured incision was focused to the incision resulting in a greater increase in the suture concentration and in the subcutaneous region directly below the incision. The four microdialysis probe design was successful in the determination of localized drug penetration in a sutured incision model. Iontophoresis enhanced skin penetration and allowed for site specific delivery when applied to a sutured incision.

An analysis of a dendritic neuron model with an active membrane site.

We formulate and analyze a mathematical model that couples an idealized dendrite to an active boundary site to investigate the nonlinear interaction between these passive and active membrane patches. The active site is represented mathematically as a nonlinear boundary condition to a passive cable equation in the form of a space-clamped FitzHugh-Nagumo (FHN) equation. We perform a bifurcation analysis for both steady and periodic perturbation at the active site. We first investigate the uncoupled space-clamped FHN equation alone and find that for periodic perturbation a transition from phase locked (periodic) to phase pulling (quasiperiodic) solutions exist. For the model coupling a passive cable with a FHN active site at the boundary, we show for steady perturbation that the interval for repetitive firing is a subset of the interval for the space-clamped case and shrinks to zero for strong coupling. The firing rate at the active site decreases as the coupling strength increases. For periodic perturbation we show that the transition from phase locked to phase pulling solutions is also dependent on the coupling strength.