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This letter introduces a new technique of inkjet printing antennas on textiles. A screen-printed interface layer was used to reduce the surface roughness of the polyester/cotton material that facilitated the printing of a continuous conducting surface. Conducting ink was used to create three inkjet-printed microstrip patch antennas. An efficiency of 53% was achieved for a fully flexible antenna with two layers of ink. Measurements of the antennas bent around a polystyrene cylinder indicated that a second layer of ink improved the robustness to bending. [ABSTRACT FROM AUTHOR]

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 ?C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications. [ABSTRACT FROM AUTHOR]

This paper studies the feasibility of vibration energy harvesting using a Halbach array. A Halbach array is a specific arrangement of permanent magnets that concentrates the magnetic field on one side of the array while cancelling the field to almost zero on the other side. This arrangement can improve electromagnetic coupling in a limited space. The Halbach array offers an advantage over conventional layouts of magnets in terms of its concentrated magnetic field and low-profile structure, which helps improve the output power of electromagnetic energy harvesters while minimizing their size. Another benefit of the Halbach array is that due to the existence of an almost-zero magnetic field zone, electronic components can be placed close to the energy harvester without any chance of interference, which can potentially reduce the overall size of a self-powered device. The first reported example of a low-profile, planar electromagnetic vibration energy harvester utilizing a Halbach array was built and tested. Results were compared to ones for energy harvesters with conventional magnet layouts. By comparison, it is concluded that although energy harvesters with a Halbach array can have higher magnetic field density, a higher output power requires careful design in order to achieve the maximum magnetic flux gradient. [ABSTRACT FROM AUTHOR]

Abstract: This paper studies the feasibility of increasing the output power of vibration piezoelectric energy harvesters using multilayer structures. In this study, single-layer, double-layer and triple-layer devices with the same resonant frequency were compared. Two design cases were studied-: In the first case, the overall thickness of all PZT layers is fixed and each PZT layer has the same thickness. In the second case, the thickness of one PZT layer is fixed. The output power of these generators was studied and compared for the conditions where all the PZT layers were connected in parallel and in series. In all cases, the multilayer structure increased the output power over the single layer structure in piezoelectric energy harvesting. [Copyright &y& Elsevier]

E-textiles have emerged as a fast-growing area in wearable technology for sports and fitness due to the soft and comfortable nature of textile materials and the capability for smart functionality to be integrated into familiar sports clothing. This review paper presents the roles of wearable technologies in sport and fitness in monitoring movement and biosignals used to assess performance, reduce injury risk, and motivate training/exercise. The drivers of research in e-textiles are discussed after reviewing existing non-textile and textile-based commercial wearable products. Different sensing components/materials (e.g., inertial measurement units, electrodes for biosignals, piezoresistive sensors), manufacturing processes, and their applications in sports and fitness published in the literature were reviewed and discussed. Finally, the paper presents the current challenges of e-textiles to achieve practical applications at scale and future perspectives in e-textiles research and development. [ABSTRACT FROM AUTHOR]

Atopic dermatitis (AD) is one of the most common skin disorders, affecting nearly one-fifth of children and adolescents worldwide, and currently, the only method of monitoring the condition is through an in-person visual examination by a clinician. This method of assessment poses an inherent risk of subjectivity and can be restrictive to patients who do not have access to or cannot visit hospitals. Advances in digital sensing technologies can serve as a foundation for the development of a new generation of e-health devices that provide accurate and empirical evaluation of the condition to patients worldwide. The goal of this review is to study the past, present, and future of AD monitoring. First, current medical practices such as biopsy, tape stripping and blood serum are discussed with their merits and demerits. Then, alternative digital methods of medical evaluation are highlighted with the focus on non-invasive monitoring using biomarkers of AD—TEWL, skin permittivity, elasticity, and pruritus. Finally, possible future technologies are showcased such as radio frequency reflectometry and optical spectroscopy along with a short discussion to provoke research into improving the current techniques and employing the new ones to develop an AD monitoring device, which could eventually facilitate medical diagnosis. [ABSTRACT FROM AUTHOR]

This paper describes a process for fabricating active electrodes and flexible conductive tracks on woven textiles for use in electrocardiogram (ECG) monitoring systems. The process involves the screen and stencil printing of dielectric and conductive polymer pastes on to a textile substrate. Unlike previous printed active electrodes which are printed on non-woven textiles, this paper reports active electrodes which are printed on to a significantly more challenging woven textile by making use of a polymer interface paste that reduces the surface roughness of the underlying textile. The conductive paths supplying power to the electrodes and carrying the buffered signal to the amplifier are implemented with a screen printable silver polymer paste. The electrode material is a stencil printed carbon loaded rubber. The buffer amplifier, which converts high impedance signals into low impedance signals, is integrated into the electrode structure, reducing the area taken up by the components and improving comfort during wearing. These electrodes are compared to passive electrodes fabricated with the same process and also to commercially available Ag/AgCl electrodes in an ECG monitoring application when the monitored subject is stationary, walking and jogging. It is shown that the textile active electrodes provide significantly improved performance compared to textile passive electrodes and similar performance to the Ag/AgCl electrodes. [ABSTRACT FROM AUTHOR]

Highlights: [•] The development of a fabrication process for textile-based biopotential monitoring networks. [•] Discussion of the design of the electrode networks and the electrical resistance of connections and electrodes. [•] Demonstration of electrode networks in 3 applications: ECG, EMG on the forearm and combined EMG and EOG on a headband. [•] For each demonstrator system an example recording of the relevant signal or signals is included. [•] A discussion of the appropriateness of these networks for AC and DC signal types. [ABSTRACT FROM AUTHOR]

In this paper a three-dimensional model of a novel electronic package has been developed using Finite element analysis to evaluate the shear load, tensile, bending and thermal stresses. Simulations of a complete flexible flip chip electronic packaging method are performed to minimize stresses on the packaged electronic device to improve robustness and reliability. Three component under-fill adhesives (Loctite 4860, Loctite 480 and Loctite 4902) and three circuit substrate materials (Kapton, Mylar and PEEK) are compared and the optimal thickness of each is found by shear load, tensile load, bending test and thermal expansion simulations. A fixed die size of 3.5 mm × 8 mm × 0.53 mm has been simulated and evaluated experimentally under shear and bending load. The shear and bending experimental results show good agreement with the simulation results and verify the simulated optimal thickness of the adhesive layer. The Kapton substrate together with the Loctite 4902 adhesive were identified as the optimum in the simulation. The simulation of under-fill adhesive and substrate thickness identified an optimum configuration of a 0.045–0.052 mm thick substrate layer and a 0.042–0.045 mm thickness of the Loctite 4902 adhesive. The bending simulation has also been used to determine the neutral axis of the encapsulated electronic package in this paper, thus identifying the optimal material and thickness for the encapsulation layer of the package. [ABSTRACT FROM AUTHOR]

Wider adoption of electronic textiles requires integration of small electronic components into textile fabrics, without comprising the textile qualities. A solution is to create a flexible yarn that incorporates electronic components within the fibres of the yarn (E-yarn). The production of these novel E-yarns was initially a craft skill, with the inclusion of package dies within the fibres of the yarn taking about 90 min. The research described here demonstrated that it is possible to produce E-yarns on an industrial scale by automating the manufacturing process. This involved adapting printed circuit board manufacturing technology and textile yarn covering machinery. The production process started with re-flow soldering of package dies onto fine multi-strand copper wire. A carrier yarn was then placed in parallel with the copper wire to provide tensile strength. The package die and adjacent carrier yarn were then encapsulated in a polymer micro-pod to provide protection from moisture ingress and from mechanical strain on the die and solder joints. The process was then completed by surrounding the micro-pod and copper interconnects with additional fibres, held tightly together with a knitted fibre-sheath. This prototype, automated production process reduced the time for embedding one micro-device within a yarn to 6 min, thus increasing the production speed, demonstrating that automation of the E-yarn production process is feasible. Prototype garments have been created using E- yarns. Further developments can include automated transfer of the yarn components from one stage of production to the next, enabling greater increases in speed of manufacture of E yarns. [ABSTRACT FROM AUTHOR]

This article presents a textile antenna for dual-band simultaneous wireless information and power transfer (SWIPT). The antenna operates as a 2.4 GHz off-body communications antenna and a sub-1 GHz (785–875 MHz) broad-beam rectenna. Incorporated within the broadside microstrip antenna is a high-impedance rectenna for sub-1 GHz power harvesting. Utilizing antenna-rectifier co-design, the rectenna eliminates the rectifier matching network. The textile antenna is fabricated on a felt substrate and utilizes conductive fabrics for the antenna. At 2.4 GHz, the antenna achieves a realized gain of 7.2 dBi on a body phantom and a minimum radiation efficiency of 63%, with and without the rectifier. The rectenna achieves a best-in-class RF to dc efficiency of 62% from 0.8 $\mu \text{W}$ /cm2, representing over 25% improvement over state-of-the-art textile rectennas and demonstrating that SWIPT does not detrimentally affect the energy harvesting or communications performance. The antenna/rectenna occupies an electrically small area of $0.213\times 0.19\,\,\lambda ^{2}_{0}$. This antenna is the first dual-band, dual-mode antenna demonstrated on textiles for SWIPT applications and the first dual-band matching network-free SWIPT rectenna. [ABSTRACT FROM AUTHOR]

This paper details how two new small molecules, based on phenanthrene, were developed, and tailored for light-emitting device applications. An account is provided of both the compound synthesis and the methodologies employed in device fabrication. The ink formulation was improved by the use of triflate counterions. Standard bottom emitting devices were constructed on ITO glass along with top emitting devices on a sputter coated silver on glass substrate. Both structures exhibit UV emissions from the synthesized molecules. Successful EL emission within the UV spectrum range has been achieved by spray coating these active molecules onto glass slides. The optimized solution-processed devices produce UV emission using a semi-transparent silver nanowire top electrode. This results in electroluminescence (EL) peaking at 398 nm, with a maximum EL emission intensity of 20.5 μW/cm2. [Display omitted] • Synthesized two novel UV light-emitting organic materials achieving high electroluminescent intensity of 20.5 μW/cm2. • Spray coating process suitable for top emitting OLECs with AgNW top electrodes demonstrated. • Hexyl imidazolium moiety enhances solubility and enables uniform spray-coated thin films without aggregation or pinholes. [ABSTRACT FROM AUTHOR]

In this article, organic light-emitting electrochemical cells (OLECs) have been fabricated on a substrate consisting of a standard woven polyester cotton textile. The textile substrate is presmoothed by first screen printing an ultraviolet (UV) curable polyurethane layer, termed the interface layer. Solution-processed spray coating is then utilized to deposit all the functional layers on the textile to achieve fully spray-coated flexible OLECs. OLEC devices were initially fabricated on ITO-coated glass substrates for process optimization. Then, the OLECs were fabricated on flexible textile using the optimized spray coating process. Finally, both OLECs devices on the glass and textile substrates were encapsulated by stencil printing epoxy before testing in an ambient environment. The OLECs on ITO-coated glass exhibit a turn-on voltage of 3 V, a brightness level of 200 cd/m2 and a lifetime of at least 60 min. The OLECs on textile exhibit a turn-on voltage of 4 V, a brightness level of 80 cd/m2 level and a lifetime of at least 30 min. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmWave) bands, a key part of future 5G networks, represent a potential channel for RF energy harvesting, where the high-gain antenna arrays offer improved end-to-end efficiency compared with sub-6-GHz networks. This article presents a broadband mmWave rectenna, the first rectenna realized on a flexible textile substrate for wearable applications. The proposed novel antenna’s bandwidth extends from 23 to 40 GHz, with a minimum radiation efficiency of 67% up to 30 GHz, over 3-dB improvement compared with a standard patch. A stable gain of more than 8 dB is achieved based on a textile reflector plane. The antenna is directly connected to a textile-based microstrip voltage doubler rectifier utilizing commercial Schottky diodes. The rectifier is matched to the antenna using a tapered line feed for high-impedance matching, achieving broadband high voltage sensitivity. The rectifier has a peak RF–dc efficiency of 12% and a 9.5-dBm 1-V sensitivity from 23 to 24.25 GHz. The integrated rectenna is demonstrated with more than 1.3-V dc output from 12 dBm of mmWave wireless power across a 28% fractional bandwidth from 20 to 26.5 GHz, a 15% half-power fractional bandwidth, and a peak output of 6.5 V from 20 dBm at 24 GHz. [ABSTRACT FROM AUTHOR]

This paper presents the development of a stretchable electronic textile (e-textile) and the design of a knee sleeve with integrated electrodes for wearable applications. The e-textile is achieved by laminating a printed conductive pattern onto knitted fabric, followed by printing a carbon rubber electrode layer on top of the conductive pads of the conductive pattern. The Young's modulus of two knitted stretchable fabrics, made of different textile yarns, is tested and their impact on the e-textile and garment properties is discussed. Four printed conductive track designs in the form of a straight line, a sine wave, a half circle, and a horseshoe are laminated on these fabrics. The four designs are investigated in terms of conductivity, change during stretching, relaxation after stretching, and wash durability. A snap connector, attached to each end of the conductive tracks, provides electronic interconnection. The e-textiles survive 100 wash cycles with a resultant maximum resistance increase of 1.44 times. A fitted knee sleeve, for use in wearable electrotherapy for knee joint pain management, is fabricated by laminating a conductive track in the optimal sinusoidal design and then printing carbon rubber electrodes on top. [Display omitted] • Introduce a method for measuring the stretchability in stretchable electronic textiles. • Evaluated the stretchability of four shaped tracks on knitted fabrics specifically for applications requiring a 50% strain. • Developed an electronic textile with the capability to withstand 100 cycles of washing. • Introduced pattern cutting techniques to the realm of wearable technology to enhance usability. • A fitted knee sleeve is fabricated by laminating an optimal sinusoidal track and printing carbon rubber electrodes on top. [ABSTRACT FROM AUTHOR]

Highlights • A novel design of a nonlinear kinetic energy harvester is presented. • Developed simulation model shows good agreement with experiments. • Performance superior to most other low-frequency design is reached. Abstract This paper presents a novel design of a nonlinear kinetic energy harvester for very low excitation frequencies below 10 Hz. The design is based on a proof mass, rolling in a circular cavity in a Tusi couple configuration. This allows for an unconstrained displacement of the proof mass while maintaining the option of keeping the energy transduction element engaged during the whole cycle and thus reducing the required number of transduction elements. Both the presented model and the fabricated prototype of the device employ electromagnetic induction to harvest energy from low frequency and low magnitude vibrations that are typically associated with human movements. The prototype demonstrated an average power of 5.1 mW from a 1.3 g periodic acceleration waveform at 2.78 Hz. The highest simulated normalized power density reaches up to 230 μW/g2/cm3, but this depends heavily on the excitation conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] A flexible and breathable fabric electrode array (FEA) has been fabricated entirely by screen printing method. [•] High conductivity (sheet resistance=49.4mΩ/sq) was achieved on fabric through use of an interface layer. [•] Materials used in the FEA which make skin contact have passed the ISO cytotoxicity test. [•] FEA can provide highly accurate assistance of joint movement. [•] Different reference postures have been achieved by stimulating an optimised selection of elements. [ABSTRACT FROM AUTHOR]

A series of printable UV emitting ionic bifluorene derivatives have been prepared incorporating pendent alkylimidazolium groups. Herein, we detail the synthesis of compounds and the methods used in device fabrication. We show how ink formulation is improved by increasing the solubility of the active bifluorene through extension of the alkyl chain length and switching the counter ion from PF 6 − to CF 3 SO 3 −. We also show how organic light emitting electrochemical cells (OLECs) can be fabricated by spray coating to achieve an active layer with a thickness of ∼150–200 nm, leading to working devices with a turn on voltage of around 6.5 V. This gives electroluminescent (EL) that peaks between 385 nm and 390 nm with a maximum EL emission intensity of 1.29 μW/cm2. Thus, EL emission within the UV range has been demonstrated successfully with the synthesised molecules via spray coating onto glass slides. UV light emitting ionic bifluorene small molecules have been synthesised and used to fabricate the OLECs on ITO glass slides. Spray coating technique has been utilized to deposit the functional layers in the OLECs. While the OLEC light emission layer is optimized to the thickness of ∼250 nm, the encapsulated devices demonstrated the turn on voltage of 6.5 V. This fabrication process can be adopted to achieve the light emitting textiles. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel sacrificial material with low curing and removal temperatures. [•] A novel method to release piezoelectric freestanding microstructures directly on fabrics using only screen printing. [•] Cantilevers with a piezoelectric layer were achieved directly on fabrics. [•] Using printed cantilevers as the basis of the sensor, in the form of motion sensors, has been demonstrated. [•] The fabrication process would not affect the flexibility and breathability of the fabric using the interface layer which is only printed under the device. [ABSTRACT FROM AUTHOR]

The work describes an improved 2-D model for a thin annulus by using a modified assumption with regard to coupled vibration. With this approach, the impedance spectrum and displacements due to radial modes, both in radial and thickness direction of a thin ring, are obtained. Bending displacement is investigated by finite element analysis (FEA) and matches our model. The bending in the thickness direction is coupled to radial modes and shows several node circles in the high radial overtone frequency range. The model is validated by FEA with excellent agreement between the new theory and FEA results. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the design, fabrication and testing of electromagnetic microgenerators. Three different designs of power generators are partially micro-fabricated and assembled. Prototype A having a wire-wound copper coil, Prototype B, an electrodeposited copper coil both on a deep reactive ion etched (DRIE) silicon beam and paddle. Prototype C uses moving NdFeB magnets in between two micro-fabricated coils. The integrated coil, paddle and beam were fabricated using standard micro-electro-mechanical systems (MEMS) processing techniques. For Prototype A, the maximum measured power output was 148nW at 8.08kHz resonant frequency and 3.9m/s2 acceleration. For Prototype B, the microgenerator gave a maximum load power of 23nW for an acceleration of 9.8m/s2, at a resonant frequency of 9.83kHz. This is a substantial improvement in power generated over other micro-fabricated silicon-based generators reported in literature. This generator has a volume of 0.1cm3 which is lowest of all the silicon-based micro-fabricated electromagnetic power generators reported. To verify the potential of integrated coils in electromagnetic generators, Prototype C was assembled. This generated a maximum load power of 586nW across 110Ω load at 60Hz for an acceleration of 8.829m/s2. [Copyright &y& Elsevier]

This paper presents a method to integrate and package an accelerometer within a textile to create an electronic textile (e-textile). The smallest commercially available accelerometer sensor (2 mm × 2 mm × 0.95 mm) is used in the e-textile and is fully integrated within the weave structure of the fabric itself, rendering it invisible to the wearer. The e-textile forms the basis of a wearable woven sleeve which is applied to arm and knee joint bending angle measurement. The integrated e-textile based accelerometer sensor system is used to identify activity type, such as walking or running, and count the total number of steps taken. Performance was verified by comparing measurements of specific elbow joint angles over the range of 0° to 180° with those obtained from a commercial bending sensor from Bend Labs and from a custom-built goniometer. The joint bending angles, measured by all three sensors, show good agreement with an error of less than ~1% of reading which provides a high degree of confidence in the e-textile sensor system. Subsequently, knee joint angles were measured experimentally on three subjects with each being tested three times on each of three activities (walking, running and climbing stairs). This allowed the minimum and maximum knee joint angles for each activity to be determined. This data is then used to identify activity type and perform step counting. [ABSTRACT FROM AUTHOR]

This paper details the design, fabrication and testing of flexible textile-concealed Radio Frequency Identification (RFID) tags for wearable applications in a smart city/smart building environment. The proposed tag designs aim to reduce the overall footprint, enabling textile integration whilst maintaining the read range. The proposed RFID filament is less than 3.5 mm in width and 100 mm in length. The tag is based on an electrically small (0.0033 λ 2 ) high-impedance planar dipole antenna with a tuning loop, maintaining a reflection coefficient less than −21 dB at 915 MHz, when matched to a commercial RFID chip mounted alongside the antenna. The antenna strip and the RFID chip are then encapsulated and integrated in a standard woven textile for wearable applications. The flexible antenna filament demonstrates a 1.8 dBi gain which shows a close agreement with the analytically calculated and numerically simulated gains. The range of the fabricated tags has been measured and a maximum read range of 8.2 m was recorded at 868 MHz Moreover, the tag's maximum calculated range at 915 MHz is 18 m, which is much longer than the commercially available laundry tags of larger length and width, such as Invengo RFID tags. The reliability of the proposed RFID tags has been investigated using a series of tests replicating textile-based use case scenarios which demonstrates its suitability for practical deployment. Washing tests have shown that the textile-integrated encapsulated tags can be read after over 32 washing cycles, and that multiple tags can be read simultaneously while being washed. [ABSTRACT FROM AUTHOR]

Previously, textile dye sensitised solar cells (DSSCs) woven using photovoltaic (PV) yarns have been demonstrated but there are challenges in their implementation arising from the mechanical forces in the weaving process, evaporation of the liquid electrolyte and partially shaded cells area, which all reduce the performance of the cell. To overcome these problems, this paper proposes a novel fabrication process for a monolithic-structured solid-state dye sensitized solar cell (ssDSSC) on textile using all solution based processes. A glass fibre textile substrate was used as the target substrate for the printed ssDSSC that contain multiple layers of electrodes and active materials. The printed ssDSSC on textile have been successfully demonstrated and compared with a reference device made with the same processes on a glass substrate. All PV textile devices were characterized under simulated AM 1.5 conditions and a peak efficiency of 0.4% was achieved. This approach is potentially suitable for the low cost integration of PV devices onto high temperature textiles, but to widen the range of applications future research is required to reduce the processing temperature to enable the device to be fabricated on the standard fabric substrates. [ABSTRACT FROM AUTHOR]

Temperature sensors are one of the most fundamental sensors and are found in industrial, environmental, and biomedical applications. The traditional approach of reading the resistive response of Positive Temperature Coefficient thermistors at DC hindered their adoption as wide-range temperature sensors. Here, we present a large-area thermistor, based on a flexible and stretchable short carbon fibre incorporated Polydimethylsiloxane composite, enabled by a radio frequency sensing interface. The radio frequency readout overcomes the decades-old sensing range limit of thermistors. The composite exhibits a resistance sensitivity over 1000 °C -1 , while maintaining stability against bending (20,000 cycles) and stretching (1000 cycles). Leveraging its large-area processing, the anisotropic composite is used as a substrate for sub-6 GHz radio frequency components, where the thermistor-based microwave resonators achieve a wide temperature sensing range (30 to 205 °C) compared to reported flexible temperature sensors, and high sensitivity (3.2 MHz/°C) compared to radio frequency temperature sensors. Wireless sensing is demonstrated using a microstrip patch antenna based on a thermistor substrate, and a battery-less radio frequency identification tag. This radio frequency-based sensor readout technique could enable functional materials to be directly integrated in wireless sensing applications., (© 2024. The Author(s).)

We present a wirelessly powered ultraviolet-C (UVC) radiation-based disinfecting bandage for sterilization and treatment in chronic wound care and management. The bandage contains embedded low-power UV light-emitting diodes (LEDs) in the 265 to 285 nm range with the light emission controlled via a microcontroller. An inductive coil is seamlessly concealed in the fabric bandage and coupled with a rectifier circuit to enable 6.78 MHz wireless power transfer (WPT). The maximum WPT efficiency of the coils is 83% in free space and 75% on the body at a coupling distance of 4.5 cm. Measurements show that the UVC LEDs are emitting radiant power of about 0.6 mW and 6.8 mW with and without fabric bandage, respectively, when wirelessly powered. The ability of the bandage to inactivate microorganisms was examined in a laboratory which shows that the system can effectively eradicate Gram-negative bacteria, Pseudoalteromonas sp. D41 strain, on surfaces in six hours. The proposed smart bandage system is low-cost, battery-free, flexible and can be easily mounted on the human body and, therefore, shows great promise for the treatment of persistent infections in chronic wound care.

Radio frequency identification (RFID) represents an emerging platform for passive RF-powered wireless sensing. Differential Multi-port RFID systems are widely used to enable multiple independent measurands to be gathered, or to overcome channel variations. This paper presents a dual-port/dual-integrated circuit (IC) RFID sensing tag based on a shared aperture dual-polarized microstrip antenna. The tag can be loaded with different sensors where the received signal strength indicator (RSSI) of one IC is modulated using a sensor, and the other acts as a measurand-insensitive reference, for differential sensing. The 868 MHz tag maintains a minimum unloaded read range of 14 m insensitive to deployment on metals or lossy objects, which represents the longest reported range of a multi-port RFID sensing tag. The tag is loaded with a light-dependent resistor (LDR) to demonstrate its functionality as a battery-less wireless RFID light sensor. Following detailed RF characterization of the LDR, it is shown that the impedance, and consequently the RSSI, of the sensing tag are modulated by changing the light intensity, whereas the reference port maintains a mostly unchanged response for a correlated channel. The proposed tag shows the potential for channel variations-tolerant differential RFID sensing platforms based on polarization-diversity antennas.

The surgeon Ambroise Paré designed an anthropomorphic hand for wounded soldiers in the 16th century. Since that time, there have been advances in technology through the use of computer-aided design, modern materials, electronic controllers and sensors to realise artificial hands which have good functionality and reliability. Data from touch, object slip, finger position and temperature sensors, mounted in the fingers and on the palm, can be used in feedback loops to automatically hold objects. A study of the natural neuromuscular systems reveals a complexity which can only in part be realised today with technology. Highlights of the parallels and differences between natural and artificial hands are discussed with reference to the Southampton Hand. The anatomical structure of parts of the natural systems can be made artificially such as the antagonist muscles using tendons. Theses solutions look promising as they are based on the natural form but in practice lack the desired physical specification. However, concepts of the lower spinal loops can be mimicked in principle. Some future devices will require greater skills from the surgeon to create the interface between the natural system and an artificial device. Such developments may offer a more natural control with ease of use for the limb deficient person.

This paper details improvements of the d33 co-efficient for thick-film lead zirconate titanate (PZT) layers. In particular, the effect of blending ball and attritor milled powders has been investigated. Mathematical modeling of the film structure has produced initial experimental values for powder combination percentages. A range of paste formulations between 8:1 and 2:1 ball to attritor milled PZT powders by weight have been mixed into a screen-printable paste. Each paste contains 10% by weight of lead borosilicate glass and an appropriate quantity of solvent to formulate a screen printable thixotropic paste. A d33 of 63.5 pC/N was obtained with a combination of 4:1 ball milled to attritor milled powder by weight. The improved paste combines the high d33 values of ball and the consistency of attritor milled powder. The measured d33 coefficient was further improved to 131 pC/N by increasing the furnace firing profile to 1000 degrees C, increasing the poling temperature to 200 degrees C, and using gold cermet and polymer electrodes that avoid silver migration effects and repeated firing of the PZT film.

This paper describes a new multi-degree-of-freedom (MDOF) ultrasonic motor that comprises few parts and is based on low-cost thick-film technology. Conventional ultrasonic motors using bulk lead zirconate titanate (PZT) or thin-film PZT layers are relatively expensive at the present time. Thick-film printed PZT technology provides the opportunity to reduce the costs of ultrasonic motors. To demonstrate the feasibility of this approach, an ultrasonic motor was fabricated from alumina using thick-film printed PZT actuators. The thick-film PZT and electrode layers were printed on a thin alumina plate, and a tiny cylinder was mounted at its center. This cylinder magnifies the lateral displacement of the stator, holds the spherical rotor, and transmits the driving force to the sphere. Three bending vibrations, B22, B30, B03, of the plate were applied to rotate the sphere. Sufficient displacements for rotating the sphere were obtained near the resonance of B22 by applying an excitation voltage of 200 V peak-to-peak via a three-phase drive circuit. Rotations in three orthogonal directions have been observed by controlling the phase of the driving signal to the PZT electrodes, and a MDOF ultrasonic motor was successfully realized.