Reconfigurable transmissive metasurface with a combination of scissor and rotation actuators for independently controlling beam scanning and polarization conversion.

Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. In this paper, we propose a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. The metasurface is constructed with rotatable unit cells (UCs) that can switch the polarization state between right-handed (RHCP) and left-handed circular polarization (LHCP) by flipping the UCs to reverse their phase variation. Moreover, independent beam scanning is achieved using the scissor actuator to linearly change the distance between the UCs. Numerical and experimental results confirm that the proposed metasurface can perform beam scanning in the range of 28° for both the positive and negative regions of a radiation pattern (RHCP and LHCP beams) at an operational frequency of 10.5 GHz.

A Low-Cost Microfluidic and Optically Transparent Water Antenna with Frequency-Tuning Characteristics.

In this study, a novel microfluidic frequency reconfigurable and optically transparent water antenna is designed using three-dimensional (3D) printing technology. The proposed antenna consists of three distinct parts, including a circularly shaped distilled water ground, a sea water-based circular segmented radiator, and a circularly shaped distilled water-based load, all ingeniously constructed from transparent resin material. The presented antenna is excited by a disk-loaded probe. The frequency of the antenna can be easily tuned by filling and emptying/evacuating sea water from the multisegmented radiator. The radiator consists of three segments with different radii, and each segment has a different resonant frequency. When the radiator is filled, the antenna resonates at the frequency of the segment that is filled. When all the radiator segments are filled, the antenna operates at the resonant frequency of 2.4 GHz and possesses an impedance bandwidth of 1.05 GHz (40%) in the range of 2.10-3.15 GHz. By filling different radiator segments, the frequency could be tuned from 2.4 to 2.6 GHz. In addition to the frequency-switching characteristics, the proposed antenna exhibits high simulated radiation efficiency (with a peak performance reaching 95%) and attains a maximum realized gain of 3.8 dBi at 2.9 GHz. The proposed antenna integrates water as its predominant constituent, which is easily available, thereby achieving cost-effectiveness, compactness, and transparency characteristics; it also has the potential to be utilized in future applications, involving transparent and flexible electronics.

Shape-Morphing Antenna Array by 4D-Printed Multimaterial Miura Origami.

The rapid development of four-dimensional (4D) printing technology has resulted in its application in various fields, including radiofrequency (RF) electronics. Moreover, because origami-inspired RF electronics provide a physically deformable geometry, they are good candidates for reconfigurable RF applications. However, previous origami-inspired RF electronics have generally been fabricated on paper for easy folding and unfolding. Although this facilitates easy fabrication, the resultant structures suffer from a lack of rigidity and stability. In this paper, we propose a 4D-printed multimaterial Miura origami structure for RF spectrum applications. For thermal actuation and robustness, the proposed structure consists of high-temperature durable cores with shape memory polymer (SMP) hinges. The high-temperature durable cores provide rigidity to the desired part and reduce the level of distortion of the conductive pattern, while the SMP hinges enable shape morphing. To demonstrate the feasibility of the technique for RF electronics, a shape-morphing pattern reconfigurable antenna array is designed at 2.4 GHz using the proposed 4D-printed multimaterial structure. Through numerical and experimental demonstrations, the proposed antenna's maximum beam direction is changed from 0° to 50° by thermally morphing the Miura origami. In addition, the antenna successfully recovers to its memorized original state.

1-Bit Transmission-Type Digital Programmable Coding Metasurface with Multi-Functional Beam-Shaping Capability for Ka-Band Applications.

Digital programmable coding metasurfaces (DPCMs) have recently attracted enormous attention and have been broadly applied, owing to their ability to manipulate electromagnetic (EM) wave behaviours and programmable multi-functionality. Recent DPCM works are divided into reflection and transmission types (R-DPCM and T-DPCM, respectively); however, there are only a few reported T-DPCM works in the millimetre-wave spectrum, owing to the difficulty of realising the large-phase controllable range while maintaining low transmission losses with electronic control components. Consequently, most millimetre-wave T-DPCMs are demonstrated only with limited functions in a single design. Additionally, all these designs use high-cost substrate materials that constrain practical applicability, owing to cost-ineffectiveness. Herein, we propose a 1-bit T-DPCM that simultaneously performs three dynamic beam-shaping functions with a single structure for millimetre-wave applications. The proposed structure is completely constructed using low-cost FR-4 materials, and operation of each meta-cell is manipulated using PIN-diodes, thus driving the achievement of multiple effective dynamic functionalities including dual-beam scanning, multi-beam shaping, and orbital-angular-momentum-mode generation. It should be noted that there are no reported millimetre-wave T-DPCMs demonstrating multi-function design, thus showing a gap in the recent literature of millimetre-wave T-DPCMs. Moreover, cost-effectiveness can be significantly enhanced, owing to the construction of the proposed T-DPCM using only low-cost material.

Foldable RF Energy Harvesting System Based on Vertically Layered Metal Electrodes within a Single Sheet of Paper.

Radio frequency energy harvesting (RFEH) systems have emerged as a critical component for powering devices and replacing traditional batteries, with paper being one of the most promising substrates for use in flexible RFEH systems. However, previous paper-based electronics with optimized porosity, surface roughness, and hygroscopicity still face limitations in terms of the development of integrated foldable RFEH systems within a single sheet of paper. In the present study, a novel wax-printing control and water-based solution process are used to realize an integrated foldable RFEH system within a single sheet of paper. The proposed paper-based device includes vertically layered foldable metal electrodes, a via-hole, and stable conductive patterns with a sheet resistance of less than 1 Ω sq-1 . The proposed RFEH system exhibits an RF/DC conversion efficiency of 60% and an operating voltage of 2.1 V in 100 s at a distance of 50 mm and a transmitted power of 50 mW. The integrated RFEH system also demonstrates stable foldability, with RFEH performance maintained up to a folding angle of 150°. The single-sheet paper-based RFEH system thus has the potential for use in practical applications associated with the remote powering of wearable and Internet-of-Things devices and in paper electronics.

Microwave Dual-Crack Sensor with a High Q-Factor Using the TE20 Resonance of a Complementary Split-Ring Resonator on a Substrate-Integrated Waveguide.

Microwave sensors have attracted interest as non-destructive metal crack detection (MCD) devices due to their low cost, simple fabrication, potential miniaturization, noncontact nature, and capability for remote detection. However, the development of multi-crack sensors of a suitable size and quality factor (Q-factor) remains a challenge. In the present study, we propose a multi-MCD sensor that combines a higher-mode substrate-integrated waveguide (SIW) and complementary split-ring resonators (CSRRs). In order to increase the Q-factor, the device is miniaturized; the MCD is facilitated; and two independent CSRRs are loaded onto the SIW, where the electromagnetic field is concentrated. The concentrated electromagnetic field of the SIW improves the Q-factor of the CSRRs, and each CSRR creates its own resonance and produces a miniaturizing effect by activating the sensor below the cut-off frequency of the SIW. The proposed multi-MCD sensor is numerically and experimentally demonstrated for cracks with different widths and depths. The fabricated sensor with a TE20-mode SIW and CSRRs is able to efficiently detect two sub-millimeter metal cracks simultaneously with a high Q-factor of 281.

Thermal spiral inductor using 3D printed shape memory kirigami.

Spiral inductors are required to realise high inductance in radio frequency (RF) circuits. Although their fabrication by using micro-electrical-mechanical systems, thin films, actuators, etc., has received considerable research attention, current approaches are both complex and expensive. In this study, we designed and fabricated a thermal spiral inductor by using a three-dimensional (3D) printed shape-memory polymer (SMP). The proposed inductor was inspired by kirigami geometry whereby a two-dimensional (2D) planar geometric shape could be transformed into a 3D spiral one to change the inductance by heating and manually transform. Mechanical and electromagnetic analyses of the spiral inductor design was conducted. Hence, in contrast with the current processes used to manufacture spiral inductors, ours can be realised via a single facile fabrication step.

Design and Fabrication of Millimeter-Wave Frequency-Tunable Metamaterial Absorber Using MEMS Cantilever Actuators.

In this paper, a MEMS (Micro Electro Mechanical Systems)-based frequency-tunable metamaterial absorber for millimeter-wave application was demonstrated. To achieve the resonant-frequency tunability of the absorber, the unit cell of the proposed metamaterial was designed to be a symmetric split-ring resonator with a stress-induced MEMS cantilever array having initial out-of-plane deflections, and the cantilevers were electrostatically actuated to generate a capacitance change. The dimensional parameters of the absorber were determined via impedance matching using a full electromagnetic simulation. The designed absorber was fabricated on a glass wafer with surface micromachining processes using a photoresist sacrificial layer and the oxygen-plasma-ashing process to release the cantilevers. The performance of the fabricated absorber was experimentally validated using a waveguide measurement setup. The absorption frequency shifted down according to the applied DC (direct current) bias voltage from 28 GHz in the initial off state to 25.5 GHz in the pull-down state with the applied voltage of 15 V. The measured reflection coefficients at those frequencies were -5.68 dB and -33.60 dB, corresponding to the peak absorptivity rates of 72.9 and 99.9%, respectively.

Hydrodynamic metasurface for programming electromagnetic beam scanning on the Azimuth and elevation planes.

The development of multifunctional and reconfigurable metasurfaces capable of manipulating electromagnetic waves has created new opportunities for various exciting applications. Extensive efforts have been applied to exploiting active metasurfaces with properties that can be controlled by externally controlling active components. However, previous approaches have poor switch isolation, power handling limitations due to nonlinear effects, and complex biasing networks. Therefore, dynamically tunable metasurfaces have become a burgeoning field in many research areas. This paper reports a hydrodynamic metasurface (HMS) that can be programmed to realize electromagnetic beam scanning on the azimuth and elevation planes. The proposed HMS platform incorporates four micropumps, each controlling four metasurface elements via microfluidic channels, built into the HMS base. The proposed platform regulates microfluidic flow through micropumps, causing irregularities in incident wave transmission phase. An HMS was built as a proof of concept, and far-field scanning experiments were performed. Numerical and experimental results verify the feasibility of electromagnetic beam scanning using a hydrodynamic metasurface. This work advances metasurface research, with very high potential for wide-ranging application and a promising route for replacing bulky cascading active components.

Debridement, antibiotics, and implant retention in infected shoulder arthroplasty caused by Serratia marcescens: a case report.

Periprosthetic joint infection (PJI) is one of the most devastating complications that can occur after shoulder arthroplasty. Although staged revision arthroplasty is the standard treatment in many cases, surgical intervention with debridement, antibiotics, and implant retention (DAIR) can be an effective option for acute PJI. We report a complex case of infected reverse shoulder arthroplasty (RSA) in a 73-year-old male. The patient had been previously treated for infected nonunion of a proximal humerus fracture caused by methicillin-resistant Staphylococcus epidermidis. He presented with a sinus tract 16 days after the implantation of RSA and was diagnosed with PJI caused by Serratia marcescens. The patient was successfully treated with DAIR and was free of infection at the last follow-up visit at 4 years postoperatively.

Osteosynthesis with autologous dual bone graft for nonunion of midshaft clavicle fractures: clinical and radiological outcomes.

PURPOSE: This study evaluated the clinical and radiological results of plate osteosynthesis with autologous cortical and cancellous bone graft for nonunion of midshaft clavicle fracture. METHODS: A retrospective review was performed for all patients who underwent surgery for midshaft clavicle nonunion at a Level I trauma center. Visual analog scales (VAS) for pain and Quick-DASH (Disabilities of Arm, Shoulder, and Hand) score were assessed. Bone union rate, change in length of affected clavicle, complications, and reoperation were determined. Risk factors were identified to determine the effect on the healing. RESULTS: Thirty-four patients were included for analysis. All patients achieved solid bone union at mean 16 weeks (range 8-36) after surgery. The mean shortening of affected clavicle decreased significantly postoperatively (P < 0.001). There was significant improvement in both pain VAS and Quick-DASH score (P < 0.001). There was no wound complication, infection, or major neurovascular injury. Ten patients (29%) complained of plate irritation and underwent removal of implant without any subsequent adverse event. Multiple regression analysis demonstrated that high-energy trauma and previous surgery were the independent risk factors that significantly delayed time to union (P < 0.05). CONCLUSION: Osteosynthesis with autologous dual bone graft for nonunion of midshaft clavicle produced an excellent union rate with good clinical outcome and minimal complications.

Four-Dimensional Printed Shape Memory Metasurface to Memorize Absorption and Reflection Functions.

Functional metasurfaces help wireless communication to reach beyond current electromagnetic control device limitations. However, current reconfigurable functional metasurfaces require separate systems for function control. In particular, it is difficult to realize millimeter-wavelength regimes due to the increasing number of active elements with the reduction in unit cell size. This paper proposes a four-dimensional printed memory metasurface to memorize absorption and reflection function in millimeter-wavelength regimes. Thus, metasurfaces with electromagnetic absorption and reflection functions can be realized through mechanical shape memory by memorizing electromagnetic properties using four-dimensional printed structures. The desired electromagnetic performance was experimentally demonstrated and deformation time to memorize the initial structure was measured. The results confirmed that the proposed four-dimensional printed metasurface has potential for considerable contribution to multifunctional wireless devices such as smart electromagnetic wave control systems in reconfigurable intelligent surface, stealth, and wireless sensing systems.

Millimeter-Wave-Based Spoof Localized Surface Plasmonic Resonator for Sensing Glucose Concentration.

Glucose-monitoring sensors are necessary and have been extensively studied to prevent and control health problems caused by diabetes. Spoof localized surface plasmon (LSP) resonance sensors have been investigated for chemical sensing and biosensing. A spoof LSP has similar characteristics to an LSP in the microwave or terahertz frequency range but with certain advantages, such as a high-quality factor and improved sensitivity. In general, microwave spoof LSP resonator-based glucose sensors have been studied. In this study, a millimeter-wave-based spoof surface plasmonic resonator sensor is designed to measure glucose concentrations. The millimeter-wave-based sensor has a smaller chip size and higher sensitivity than microwave-frequency sensors. Therefore, the microfluidic channel was designed to be reusable and able to operate with a small sample volume. For alignment, a polydimethylsiloxane channel was simultaneously fabricated using a multilayer bonding film to attach the upper side of the pattern, which is concentrated in the electromagnetic field. This real-time sensor detects the glucose concentration via changes in the S11 parameter and operates at 28 GHz with an average sensitivity of 0.015669 dB/(mg/dL) within the 0-300 mg/dL range. The minimum detectable concentration and the distinguishable signal are 1 mg/dL and 0.015669 dB, respectively, from a 3.4 µL sample. The reusability and reproducibility were assessed through replicates.

Dynamic phase control with printing and fluidic materials' interaction by inkjet printing an RF sensor directly on a stereolithographic 3D printed microfluidic structure.

Stereolithographic (SL) three-dimensional (3D) printing of microfluidic channels and inkjet printing of radio frequency (RF) electronics are promising lab-on-a-chip technologies. However, the effective integration of the two techniques has been challenging since the fabricated parts need to be combined via an additional bonding process, such as plasma bonding. This study proposes combining RF electronics with SL printed microfluidic structures by directly inkjet printing onto a 3D printed mould. This allows the inkjet printing of RF electronics with high conductivity (8 × 106 S m-1) and high resolution (50 µm) as a surface modification of the 3D printed mould. This process combines the three-dimensional printing of microfluidic parts and the inkjet printing of RF sensors into a single process. The proposed approach increases the interaction between a printed RF part and a fluid material by adjusting the distance between them, and it can be applied to various resins and 3D printing methods. Furthermore, the proposed fabrication process was applied to a dynamic phase advanced and delayed transmission line (TL) operating at 3.8 GHz as a fluidic sensor. Consequently, using the same pattern, a higher phase shift range per microliter of 10° was obtained than the 1° for conventional phase shift TLs.

Electromagnetic Control by Actuating Kirigami-Inspired Shape Memory Alloy: Thermally Reconfigurable Antenna application.

Electromagnetic responses are generally controlled electrically or optically. However, although electrical and optical control allows fast response, they suffer from switching or tuning range limitations. This paper controls electromagnetic response by mechanical transformation. We introduce a novel kirigami-inspired structure for mechanical transformation with less strength, integrating a shape memory alloy actuator into the kirigami-inspired for mechanical transformation and hence electromagnetic control. The proposed approach was implemented for a reconfigurable antenna designed based on structural and electromagnetic analyses. The mechanical transformation was analyzed with thermal stimulus to predict the antenna geometry and electromagnetic analysis with different geometries predicted antenna performance. We numerically and experimentally verified that resonance response was thermally controlled using the kirigami-inspired antenna integrated with a shape memory alloy actuator.

Comparison between SLAP Repair and Biceps Tenodesis with Concomitant Rotator Cuff Repair in Patients Older than 45 Years: Minimum 2-Year Clinical and Imaging Outcomes.

BACKGROUD: There is controversy over how to surgically treat symptomatic superior labrum anterior to posterior (SLAP) tears in middle-aged patients with concomitant rotator cuff tears. The aim of the study was to compare the clinical and imaging outcomes of SLAP repair versus biceps tenodesis (BT) each combined with arthroscopic rotator cuff repair (ARCR). METHODS: We retrospectively reviewed 35 patients older than 45 years who underwent arthroscopic surgery to manage concomitant SLAP tears and rotator cuff tears. In addition to ARCR, 17 patients underwent SLAP repair, whereas 18 patients underwent BT. Shoulder range of motion (ROM), visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES) score, Constant score, and University of California at Los Angeles (UCLA) score were used for clinical assessment. The integrity of rotator cuff repair and change of superior labrum-biceps complex were evaluated by postoperative magnetic resonance imaging (MRI). RESULTS: There was significant improvement in the pain VAS and all functional scores in both groups (p < 0.001) at a mean followup of 29.4 ± 11.4 months (range, 24-84 months) postoperatively. Shoulder ROM showed significant improvement postoperatively (p < 0.05). No significant difference in outcomes could be found between the 2 groups after surgery. The retear rate of rotator cuff repair on MRI was 11.8% in the SLAP repair group and 11.1% in the BT group. CONCLUSIONS: In middle-aged patients with combined SLAP lesions and rotator cuff tears, both SLAP repair and BT can be safe adjuncts to ARCR.

Simplified Approach to Detect Dielectric Constant Using a Low-Cost Microfluidic Quarter Mode Substrate-Integrated Waveguide.

Liquid materials' characterization using commercial probes and radio frequency techniques is expensive and complex. This study proposes a compact and cost-effective radio frequency sensor system to measure the dielectric constant using a three-material calibration. The simplified approach measures reflection coefficient magnitudes for all four materials rather than the complex values in conventional permittivity detection systems. We employ a sensor module based on a circular substrate-integrated waveguide with measured unloaded quality factor = 910 to ensure measurement reliability. Miniaturized quarter-mode substrate-integrated waveguide resonators are integrated with four microfluidic channels containing three known materials and one unknown analyte. Step-wise measurement and linearity ensures maximum 4% error for the dielectric constant compared with results obtained using a high-performance commercial product.

Dynamically Self-Reconfigurable Multifunctional All-Passive Metasurface.

Reconfigurable metasurfaces have shown their great potentials and are needed in multiple applications, such as radar, wireless communication systems, and security. To date, however, it is challenging to realize low-cost and simple reconfigurable and multifunctional metasurfaces. In this proposed work, we present a low-cost and simple multifunctional all-passive metasurface that achieves a self-switching characteristic relying on a modulating incident wave without additional supporting devices. As proof-of-principle application examples, we realize a prototype of the proposed all-passive metasurface with an antenna for radome applications, that can achieve self-switching operation between a high directional antenna at the transmitting mode, and radar absorbing structure and reflector at the receiving mode. The reported strategy will open up a new avenue for future smart devices and could extend to some smarter applications such as high-power pulse skin protection for electronic devices and self-reconfigurable beam switching metasurface.

Clinical and Imaging Outcomes After Revision Open Rotator Cuff Repair: A Retrospective Review of a Midterm Follow-Up Study.

BACKGROUND: Revision open rotator cuff repair (ORCR) has been associated with unpredictable functional outcome with concerns of deltoid detachment. The aim of this study was to evaluate the clinical and imaging outcomes of revision ORCR. MATERIALS AND METHODS: The study retrospectively reviewed 30 consecutive patients (mean age 60.4 ± 7.2 years) who underwent revision ORCR after failed rotator cuff repair. Pain visual analog scale (VAS), Constant and American Shoulder Elbow Surgeon (ASES) score were assessed preoperatively and at mean 58-month follow-up (range 24-120 months). The acromio-humeral distance (AHD) was measured on pre- and postoperative radiograph. Tear size and fatty infiltration of rotator cuff were evaluated by preoperative magnetic resonance imaging (MRI) study. The retear rate, change of fatty infiltration and deltoid origin integrity were evaluated by postoperative MRI. RESULTS: There was significant improvement of pain VAS and functional outcome scores (all p < 0.001). AHD showed no significant change after surgery. On postoperative MRI, the retear rate was 43% (13/30). However, the size of the tendon defect was smaller than that of pre-revision tear (p = 0.006). The patients who had intact tendon had significantly better functional outcomes than those with retear. The intact group had significantly higher AHD both pre- and postoperatively than the retear group. There was no change of fatty infiltration after surgery. Four patients (13%, 4/30) showed thinning of deltoid origin on postoperative MRI, but showed no weakness on clinical examination. CONCLUSION: Revision ORCR resulted in improved outcomes in pain relief and shoulder function, with low rate of subclinical deltoid thinning.

Prediction of pathologic complete response using image-guided biopsy after neoadjuvant chemotherapy in breast cancer patients selected based on MRI findings: a prospective feasibility trial.

PURPOSE: Accurate prediction of pathologic complete response (pCR) in breast cancer using magnetic resonance imaging (MRI) and ultrasound (US)-guided biopsy may aid in selecting patients who forego surgery for breast cancer. We evaluated the accuracy of US-guided biopsy aided by MRI in predicting pCR in the breast after neoadjuvant chemotherapy (NAC). METHODS: After completion of NAC, 40 patients with near pCR (either tumor size ≤ 0.5 cm or lesion-to-background signal enhancement ratio (L-to-B SER) ≤ 1.6 on MRI) and no diffused residual microcalcifications were prospectively enrolled at a single institution. US-guided multiple core needle biopsy (CNB) or vacuum-assisted biopsy (VAB) of the tumor bed, followed by standard surgical excision, was performed. Matched biopsy and surgical specimens were compared to assess pCR. The negative predictive value (NPV), accuracy, and false-negative rate (FNR) were analyzed. RESULTS: pCR was confirmed in 27 (67.5%) surgical specimens. Preoperative biopsy had an NPV, accuracy, and FNR of 87.1%, 90.0%, and 30.8%, respectively. NPV for hormone receptor-negative and hormone receptor-positive tumors were 83.3% and 100%, respectively. Obtaining at least 5 biopsy cores based on tumor size ≤ 0.5 cm and an L-to-B SER of ≤ 1.6 on MRI (27 patients) resulted in 100% NPV and accuracy. No differences in accuracy were noted between CNB and VAB (90% vs. 90%). CONCLUSIONS: Investigation using stringent MRI criteria and ultrasound-guided biopsy could accurately predict patients with pCR after NAC. A larger prospective clinical trial evaluating the clinical safety of breast surgery omission after NAC in selected patients will be conducted based on these findings.