RESUMEN
This article presents a methodology to recycle and upgrade a 4-DOF educational robot manipulator with a gripper. The robot is upgraded by providing it an artificial vision that allows obtaining the position and shape of objects collected by it. A low-cost and open-source hardware solution is also proposed to achieve motion control of the robot through a decentralized control scheme. The robot joints are actuated through five direct current motors coupled to optical encoders. Each encoder signal is fed to a proportional integral derivative controller with anti-windup that employs the motor velocity provided by a state observer. The motion controller works with only two open-architecture Arduino Mega boards, which carry out data acquisition of the optical encoder signals. MATLAB-Simulink is used to implement the controller as well as a friendly graphical interface, which allows the user to interact with the manipulator. The communication between the Arduino boards and MATLAB-Simulink is performed in real-time utilizing the Arduino IO Toolbox. Through the proposed controller, the robot follows a trajectory to collect a desired object, avoiding its collision with other objects. This fact is verified through a set of experiments presented in the paper.
RESUMEN
High-repetition-rate burst-mode ultrafast-laser ablation and disruption of biological tissues depends on interaction of each pulse with the sample, but under those particular conditions which persist from previous pulses. This work characterizes and compares the dynamics of absorption and scattering of a 133-MHz repetition-rate, burst-mode ultrafast-pulse laser, in agar hydrogel targets and distilled water. The differences in energy partition are quantified, pulse-by-pulse, using a time-resolving integrating-sphere-based device. These measurements reveal that high-repetition-rate burst-mode ultrafast-laser ablation is a highly dynamical process affected by the persistence of ionization, dissipation of plasma plume, neutral material flow, tissue tensile strength, and the hydrodynamic oscillation of cavitation bubbles.
RESUMEN
A 3D living-cell culture in hydrogel has been developed as a standardized low-tensile-strength tissue proxy for study of ultrafast, pulsetrain-burst laser-tissue interactions. The hydrogel is permeable to fluorescent biomarkers and optically transparent, allowing viable and necrotic cells to be imaged in 3D by confocal microscopy. Good cell-viability allowed us to distinguish between typical cell mortality and delayed subcellular tissue damage (e.g., apoptosis and DNA repair complex formation), caused by laser irradiation. The range of necrosis depended on laser intensity, but not on pulsetrain-burst duration. DNA double-strand breaks were quantified, giving a preliminary upper limit for genetic damage following laser treatment.