Large scale indium tin oxide (ITO) one dimensional gratings for ultrafast signal modulation in the visible spectral region

Indium tin oxide (ITO) is a heavily doped semiconductor with a plasmonic response in the near infrared region. When exposed to light, the distribution of conduction band electron induces a change in the real and imaginary parts of the dielectric permittivity. The coupling of the electromagnetic waves with the electrons in the conduction band of metallic nanostructures with ultrashort light pulses results in a nonlinear plasmonic response. Such optical modulation occurring on ultrafast time scales, e.g. picosecond response times, can be exploited and used to create integrated optical components with terahertz modulation speed. Here, we present a photophysical study on a one dimensional ITO grating, realized using a femtosecond micromachining process, a very industrially accessible technology. The geometries, dimensions and pitch of the various gratings analyzed are obtained by means of direct ablation in a controlled atmosphere of a homogeneous thin layer of ITO deposited on a glass substrate. The pitch has been selected in order to obtain a higher order of the photonic band gap in the visible spectral region. Femtosecond micromachining technology guarantees precision, repeatability and extreme manufacturing flexibility. By means of ultrafast pump-probe spectroscopy, we characterize both the plasmon and inter-band temporal dynamics. We observe a large optical nonlinearity of the ITO grating in the visible range, where the photonic band gap occurs, when pumped at the surface plasmon resonance in the near infrared (1500 nm) region. All together, we show the possibility of all-optical signal modulation with heavily doped semiconductors in their transparency window with a picosecond response time through the formation of ITO grating structures

Uso de espátula e dissector para otimização da ceratoplastia lamelar anterior profunda (DALK)

Objective: We describe a novel spatula and dissector to facilitate the big-bubble technique in deep anterior lamellar keratoplasty (DALK). Methods: A 29-year-old man who was diagnosed with bilateral keratoconus underwent deep anterior lamellar keratoplasty (DALK). After 350μm partial thickness incision of the recipient cornea, the Bonfadini dissector was inserted at the deepest point in the peripheral incision and could be advanced to the center of the cornea safely because of its semi-sharp tip. After achieving the big-bubble (BB) separation of Descemet membrane (DM) from the overlying stroma, the anterior stromal disc was removed. Viscoelastic material was placed on the stromal bed to prevent uncontrolled collapse and perforation of DM during the paracentesis blade incision into the BB. We could detect the safe opening of the BB using the Bonfadini dissector by the leakage of air bubbles into the viscoelastic material. After injecting viscoelastic material into the BB space, we inserted the Bonfadini spatula into the bigbubble safely because of its curved profile and blunt edges. The groove along the length of the Bonfadini spatula enables safe and efficient incision or the residual stromal tissue using the pointed end of a sharp blade while protecting the underlying DM. After removal of posterior stroma, the donor button was sutured with 16 interrupted 10-0 nylon sutures. Results: This technique and the use of the Bonfadini spatula and dissector facilitate exposure of Descemet membrane. Conclusion: The smooth Bonfadini DALK spatula and dissector facilitate safe and efficient completion of DALK surgery.Objetivo: Descrevemos o uso de novos instrumentais cirúrgicos para facilitar a técnica de big-bubble na ceratoplastia lamelar anterior profunda (DALK). Métodos: Paciente masculino, 29 anos, foi diagnosticado com ceratocone bilateral e submetido à ceratoplastia lamelar anterior profunda (DALK). Após incisão da córnea receptora numa profundidade de 350μm de espessura parcial, o dissector Bonfadini foi inserido no ponto mais profundo da incisão periférica e pode avançar para o centro da córnea com segurança devido à sua ponta semiafiada. Depois de realizar a big-bubble (BB) e atingir a separação da Membrana de Descemet (MD) do estroma sobrejacente, o disco corneano de estroma anterior foi removido. Um viscoelástico foi colocado sobre o leito do estroma remanescente para impedir o colapso não-controlado e perfuração da MD durante a incisão na BB com lâmina de paracentese. Verificamos segurança no rompimento do estroma remanescente com o auxílio do dissector Bonfadini, para liberação da bolha de ar da BB através do viscoelástico. Depois de injetar o viscoelástico no espaço da BB, inserimos a espátula Bonfadini neste espaço, o que demonstrou-se seguro devido ao formato curvo e das bordas arredondadas do instrumental. A chanfradura ao longo do comprimento da espátula Bonfadini permite a incisão pela ponta de uma lâmina afiada, protegendo assim a MD subjacente. Após a remoção do estroma posterior, o botão doador foi suturado com 16 pontos interrompidos de fio nylon 10.0. Resultados: Esta técnica e o uso da espátula Bonfadini e dissector facilitam a exposição de membrana de Descemet. Conclusão: A superfície lisa da espátula Bonfadini e dissector, facilitam a realização segura e eficiente da ceratoplastia lamelar anterior profunda (DALK).Johns Hopkins School of Medicine Wilmer Eye Institute Cornea & Anterior Segment ServiceRio de Janeiro Eye BankUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaCatholic University of Korea College of MedicineUNIFESP, EPMSciEL

Fully direct written organic micro-thermoelectric generators embedded in a plastic foil

Organic materials have attracted great interest for thermoelectric applications due to their tuneable electronic properties, solution processability and earth-abundance, potentially enabling high-throughput realization of low-cost devices for low-power energy harvesting applications. So far, organic thermoelectricity has primarily focused on materials development, with less attention given to integrated generators. Yet, future applications will require the combination of efficient generators architectures and scalable manufacturing techniques to leverage the advantages of such promising materials. Here we report the realization of a monolithic organic micro-thermoelectric generator (μ-OTEG), using only direct writing methods, embedding the thermoelectric legs within a plastic substrate through a combination of direct laser writing and inkjet printing techniques. Employing PEDOT:PSS for the p-type legs and a doped fullerene derivative for the n-type ones, we demonstrate a μ-OTEG with power density of 30.5 nW/cm2 under small thermal gradients, proving the concrete possibility of achieving power requirements of low-power, distributed sensing applications

Quantitative analysis of iris parameters in keratoconus patients using optical coherence tomography

ABSTRACTPurpose:To investigate the relationship between quantitative iris parameters and the presence of keratoconus.Methods:Cross-sectional observational study that included 15 affected eyes of 15 patients with keratoconus and 26 eyes of 26 normal age- and sex-matched controls. Iris parameters (area, thickness, and pupil diameter) of affected and unaffected eyes were measured under standardized light and dark conditions using anterior segment optical coherence tomography (AS-OCT). To identify optimal iris thickness cutoff points to maximize the sensitivity and specificity when discriminating keratoconus eyes from normal eyes, the analysis included the use of receiver operating characteristic (ROC) curves.Results:Iris thickness and area were lower in keratoconus eyes than in normal eyes. The mean thickness at the pupillary margin under both light and dark conditions was found to be the best parameter for discriminating normal patients from keratoconus patients. Diagnostic performance was assessed by the area under the ROC curve (AROC), which had a value of 0.8256 with 80.0% sensitivity and 84.6% specificity, using a cutoff of 0.4125 mm. The sensitivity increased to 86.7% when a cutoff of 0.4700 mm was used.Conclusions:In our sample, iris thickness was lower in keratoconus eyes than in normal eyes. These results suggest that tomographic parameters may provide novel adjunct approaches for keratoconus screening