RESUMEN

In health care institutions and at home, assessing the needs of patients with wounds, setting up a protocol adapted to the condition of the wound, and providing human assistance and resources optimize the positive evolution of the situation. In the home, the links between city and hospital professionals promote comprehensive support for the person. In this perspective, the wound and healing referral nurse at the hospital at home shares her expertise with private nurses to improve the quality of care.

Asunto(s)

RESUMEN

Commercial electrowetting-based liquid lenses are optical devices containing two immiscible liquids as an optical medium. The first phase is a droplet of a high refractive index oil phase placed in a ring-shaped chassis. The second phase is electrically conductive and has a similar density over a wide temperature range. Droplet curvature and refractive index difference of two liquids determine the optical strength of the lens. Liquid lenses take advantage of the electrowetting effect, which induces a change of the interface's curvature by applying a voltage, thereby providing a variable focal that is useful in autofocus applications. The first generation of lens modules were highly reliable, but the optical strength and application scope was limited by a low refractive index difference between the oil and conductive phase. Described herein is an effort to increase the refractive index difference between both phases, while maintaining other critical application characteristics of the liquids, including a low freezing point, viscosity, phase miscibility, and turbidity after thermal shock. An important challenge was the requirement that both phases have to have matching densities and hence had to be optimized simultaneously. Using high throughput experimentation in conjunction with statistical design of experiments (DOE), we have developed a series of empirical models to predict multiple physicochemical properties of both phases and derived ideal locations within the formulation space. This approach enabled the development of reliable liquid lenses with a previously unavailable refractive index difference of Δ nD of ≥0.290, which enabled true optical zooming capability.

Asunto(s)

RESUMEN

Insulating materials from the parylene family were investigated for use in low-power-consumption electrowetting-based liquid lenses. It was shown that for DC-driven operations, parylene C leads to hysteresis, regardless of the presence of a hydrophobic top coat. This hysteresis was attributed to the non-negligible time needed to reach a stable contact angle, due to charge injection and finite conductivity of the material. It was further demonstrated that by using materials with better insulating properties, such as parylene HT and VT4, satisfactory results can be obtained under DC voltages, reaching a low contact angle hysteresis of below 0.2°. We propose a simplified model that takes into account the injection of charges from both sides of the insulating material (the liquid side and the electrode side), showing that electrowetting response can be both increased and decreased.