CMOS compatible metamaterial absorbers for hyperspectral medium wave infrared imaging and sensing applications

We experimentally demonstrate a CMOS compatible medium wave infrared metal-insulator-metal (MIM) metamaterial absorber structure where for a single dielectric spacer thickness at least 93% absorption is attained for 10 separate bands centred at 3.08, 3.30, 3.53, 3.78, 4.14, 4.40, 4.72, 4.94, 5.33, 5.60 μm. Previous hyperspectral MIM metamaterial absorber designs required that the thickness of the dielectric spacer layer be adjusted in order to attain selective unity absorption across the band of interest thereby increasing complexity and cost. We show that the absorption characteristics of the hyperspectral metamaterial structures are polarization insensitive and invariant for oblique incident angles up to 25° making them suitable for practical implementation in an imaging system. Finally, we also reveal that under TM illumination and at certain oblique incident angles there is an extremely narrowband Fano resonance (Q < 50) between the MIM absorber mode and the surface plasmon polariton mode that could have applications in hazardous/toxic gas identification and biosensing

Octave-spanning broadband absorption of terahertz light using metasurface fractal-cross absorbers

Synthetic fractals inherently carry spatially encoded frequency information that renders them as an ideal candidate for broadband optical structures. Nowhere is this more true than in the terahertz (THz) band where there is a lack of naturally occurring materials with valuable optical properties. One example are perfect absorbers that are a direct step toward the development of highly sought after detectors and sensing devices. Metasurface absorbers that can be used to substitute for natural materials suffer from poor broadband performance, while those with high absorption and broadband capability typically involve complex fabrication and design and are multilayered. Here, we demonstrate a polarization-insensitive ultrathin (∼λ/6) planar metasurface THz absorber composed of supercells of fractal crosses capable of spanning one optical octave in bandwidth, while still being highly efficient. A sufficiently thick polyimide interlayer produces a unique absorption mechanism based on Salisbury screen and antireflection responses, which lends to the broadband operation. Experimental peak absorption exceeds 93%, while the average absorption is 83% from 2.82 THz to 5.15 THz. This new ultrathin device architecture, achieving an absorption-bandwidth of one optical octave, demonstrates a major advance toward a synthetic metasurface blackbody absorber in the THz ban

A study of clinicoradiological and functional outcomes of intramedullary nailing in diaphyseal radius ulna fractures

Background: The aim of this study was to evaluate the results of intramedullary nailing in diaphyseal fractures of radius and ulna in age group of 10 to 49 years and to understand its clinicoradiological and functional results.Methods: This is a retrospective case series study of forearm bone fractures and the selected management for the same over a period of 3 years. We chose the cases in which intramedullary nailing was the treatment modality which were followed up over a period of minimum 6 months. Patients with galeazzi variety, monteggia variety, pathological fracture or non-union after previous surgery were excluded. The outcomes were then evaluated with disabilities of the arm, shoulder and hand (DASH) score, Green and O’Brien score, and Grace and Eversmann functional outcome score.Results: Of the 22 patients, 10 patients had excellent functional outcome according to Grace and Eversmann score, 7 patients had good outcome, 4 patients had acceptable while 1 was unacceptable. Green and O’Brien also had similar results, except that patients among fair category were 3 and poor category were 3. The mean DASH score was 16.2.Conclusions: This study shows that closed method for fixation by intramedullary nailing of both bone forearm fractures leads to excellent to good functional outcomes (according to DASH score, Green and O Brien, and Grace and Eversmann score) with less complications. In 6 months follow up x ray there is radiological union in all cases with no angulation, malunion or non-union.

Generalized four-point characterization method for resistive and capacitive contacts

In this paper, a four-point characterization method is developed for resistive samples connected to either resistive or capacitive contacts. Provided the circuit equivalent of the complete measurement system is known including coaxial cable and connector capacitances as well as source output and amplifier input impedances, a frequency range and capacitive scaling factor can be determined, whereby four-point characterization can be performed. The technique is demonstrated with a discrete element test sample over a wide frequency range using lock-in measurement techniques from 1 Hz - 100 kHz. The data fit well with a circuit simulation of the entire measurement system. A high impedance preamplifier input stage gives best results, since lock-in input impedances may differ from manufacturer specifications. The analysis presented here establishes the utility of capacitive contacts for four-point characterizations at low frequency.Comment: 21 pages, 10 figure

Fractal Metasurface Absorbers with Octave-Spanning Bandwidth

Synthetic fractals offer a degree of freedom for varying resonance frequency, and are an ideal candidate for broadband absorbing devices – especially in the terahertz (THz) band where there is a lack of naturally absorbing materials. Metasurface absorbers often suffer from poor broadband performance, whilst strongly-absorbing broadband devices are typically complex multilayer structures [1,2]. Here, we overcome this limitation by developing an ultra-broadband metasurface absorber based on fractal cross resonators [3], capable of experimentally achieving one Optical Octave bandwidth and peak absorption of 93%. We attribute this to a novel absorption mechanism based on both Salisbury screen and anti-reflection responses. Such work is beneficial in realising THz blackbody absorbers, and for bolometric sensing capabilities

Ultra-narrow line width polarization-insensitive filter using a symmetry-breaking selective plasmonic metasurface

Plasmonic metasurfaces provide unprecedented control of the properties of light. By designing symmetry-breaking nanoholes in a metal sheet and engineering the optical properties of the metal using geometry, highly selective transmission and polarisation control of light is obtained. To date such plasmonic filters have exhibited broad (> 200 nm) transmission linewidths in the NIR and as such are unsuitable for applications requiring narrow passbands, e.g. multi-spectral imaging. Here we present a novel sub-wavelength elliptical and circular nanohole array in a metallic film that simultaneously exhibits high transmission efficiency, polarisation insensitivity and narrow linewidth. The experimentally obtained linewidth is 79 nm with a transmission efficiency of 44%. By examining the electric and magnetic field distributions for various incident polarisations at the transmission peak we show that the narrowband characteristics are due to a Fano resonance. Good agreement is obtained between the experimental data, simulations and analytical calculations. Our design can be modified to operate in other regions of the electromagnetic spectrum and these filters may be integrated with suitable detectors such as photodiodes and single photon avalanche diode (SPAD) arrays

Stent vs. Stent-less Ileal Conduits After Radical Cystectomies: Is There Difference In Early Postoperative Outcomes?

Placing ureteral stents at the ureteroileal anastomosis for radical cystectomy with ileal conduit (RCIC) diversion has long been common practice, which has recently been called into question. In this study, we aim to investigate the difference in 30-day outcomes between patients who did and did not receive ureteral stents after RCIC.https://jdc.jefferson.edu/urologyfposters/1003/thumbnail.jp

Noise characteristics with CMOS sensor array scaling

An important consideration when scaling semiconductor sensor devices is the effect it may have on noise performance. Overall signal to noise ratio can be improved both by increasing sensor size, or alternatively by averaging the signal from two or more smaller sensors. In the design of sensor systems it is not immediately clear which is the best strategy to pursue. In this paper, we present a detailed theoretical and experimental study based on three different sensor arrays that show that an array of small independent sensors is always less noisy than a large sensor of the same size

Patient Factors Impacting Perioperative Outcomes for T1b-T2 Localized Renal Cell Carcinoma May Guide Decision for Partial versus Radical Nephrectomy

There remains debate surrounding partial (PN) versus radical nephrectomy (RN) for T1b-T2 renal cell carcinoma (RCC). PN offers nephron-sparing benefits but involves increased perioperative complications. RN putatively maximizes oncologic benefit with complex tumors. We analyzed newly available nephrectomy-specific NSQIP data to elucidate predictors of perioperative outcomes in localized T1b-T2 RCC. We identified 2094 patients undergoing nephrectomy between 2019-2020. Captured variables include surgical procedure and approach, staging, comorbidities, prophylaxis, peri-operative complications, reoperations, and readmissions. 816 patients received PN while 1278 received RN. Reoperation rates were comparable; however, PN patients more commonly experienced 30-day readmissions (7.0% vs. 4.7%, p = 0.026), bleeds (9.19% vs. 5.56%, p = 0.001), renal failure requiring dialysis (1.23% vs. 0.31%, p = 0.013) and urine leak or fistulae (1.10% vs. 0.31%, p = 0.025). Infectious, pulmonary, cardiac, and venothromboembolic event rates were comparable. Robotic surgery reduced occurrence of various complications, readmissions, and reoperations. PN remained predictive of all four complications upon multivariable adjustment. Several comorbidities were predictive of complications including bleeds and readmissions. This population-based cohort explicates perioperative outcomes following nephrectomy for pT1b-T2 RCC. Significant associations between PN, patient-specific factors, and complications were identified. Risk stratification may inform management to improve post-operative quality of life (QOL) and RCC outcomes