Guest Editorial Microassembly for Manufacturing at Small Scales.

International audienceMICROELECTRONICS brought an information revolution through integrating a vast number of microscopic transistors. Much progress has beenmade inminiaturization and integration of MEMS or MOEMS (Micro-(Opto-)Electro-Mechanical-Systems to produce accelerometers, inkjet printer heads, micro-mirrors, micro-relays, and pressure sensors. A new generation of MEMS is rapidly moving toward highly integrated, more complex heterogeneous microsystems with increased functionalities. Many limitations remain that are extremelydifficult to overcome, especially concerning processes and materials incompatibilities. microassembly is a natural and powerful approach to overcome these processes incompatibilities and to facilitate complex, heterogeneous, 3D, or out of plane integration. By using basic micro-scale components, microassembly constitutes a new alternative of Microsystems production that may lead to cost savings and shorter development cycle times. Because of the size of the components and of the required precision, automation is needed

Magnetically Levitated Microrobotic Mixer

Microfluidic systems, when combined with microrobots, offer enhanced precision in chemical synthesis by precisely controlling reaction conditions. These systems, when integrated with analytical tools, allow for real-time monitoring and are cost-efficient due to their minimal volume requirements, thereby reducing risks associated with hazardous chemicals. In our study, we have investigated the mixing efficiency of Thymolphthalein indicator with NaOH solution in a magnetically levitated microrobotic mixer. A PMMA microfluidic chip was used to transfer fluid containing two different solutions and achieve fast and efficient mixing. By adjusting five different flow rates and altering the rotational speeds of the microrobots, the mixing efficiency was observed. The studies were carried out under the laminar regime, with incompressible Newtonian flow rates and varying actuator speeds. The measurement of mixing efficiency was accomplished through the calculation of changes in pixel intensity observed in microscopic images acquired throughout the mixing process. The presence of the microrobots resulted in the best efficiency at 80.37% at 500 rpm and 7 mL/min flow rate. Their potential in advanced reactions, such as nanoparticle synthesis and encapsulation, suggests promising avenues for improving product yields.Comment: 5 pages, 2 figures, 1 tabl

On dynamics of a rigid body moving on a horizontal plane by means of motion of an internal particle

We deal with mechanical system consisting of a body moving on a horizontal plane and a particle which moves within the body in a circle. We suppose that dry friction acts between the plane and the body and assume that the body moves without jumps on the plane. We study the dynamics of the above system in detail. In particular, we show that, depending on parameters values, motion of the body approaches to one of three periodic modes

Modeling and experimental validation of a parallel microrobot for biomanipulation

The main purpose of this project is the development of a commercial micropositioner's (SmarPod 115.25, SmarAct GmbH) geometrical model. SmarPod is characterized by parallel kinematics and is employed for precise and accurate sample's positioning under SEM microscope, being vacuum-compatible, for various applications. Geometrical modeling represents the preliminar step to fully understand, and possibly improve, robot's closed loop behaviour in terms of task's quality precision, when enterprises does not provide sufficient documentation. The robotic system, in fact, represents in this case a "black box" from which it's possible to extract information. This step is essential in order to improve, consequently, the reliability of bio-microsystem manipulation and characterization. Disposing of a detailed microrobot's model becomes essential to deal with the typical lack of sensing at microscale, as it allows a 3D precise and adequate reconstruction, realized through proper softwares, of the manipulation set-up. The roles of Virtual Reality (VR) and of simulations, carried out, in this case, in Blender environment, are asserted as well as an essential helping tool in mycrosystem's task planning. Blender is a professional free and open-source 3D computer graphics software and it is proven to be a basic instrument to validate microrobot's model, even to simplify it in case of complex system's geometries

Design and implementation of a bristle bot swarm system

Swarm robotics focuses on the study and development of robot systems containing a large number of agents that interact with each other in a collective behaviour in order to achieve tasks or overcome obstacles. Bristlebots are vibration-driven mobile robots. They are characterized by small size, high speed, simple design and low costs for production and application – qualities which are advantageous for agents of swarm robotic systems. However, most studies have been developed over systems with no control or systems with two or more actuators. The aim of this master thesis is the development of a bristle based robot agent for a swarm robotics microsystem with units for locomotion, sensing, data processing, control, communication and energy storage. New approaches in modelling and development of swarm agents are given, and a robot prototype is presented. The robot is driven by a single DC motor and uses a bristle system to create locomotion. It should be noted, that within the system design, considerations for the size, weight and minimalist architecture are taken. Experiments are presented and the system’s capabilities for displacement, velocity and trajectory generation are analysed. While the parallel velocity maintains a positive magnitude in both motor rotation directions, the rotation speed and transversal velocity of the robot have opposite directions, creating curved trajectories with opposite orientations. In Frequencies up to 210 Hz, the rotation direction of the robot is maintained while the magnitude slightly varies. However, for higher frequencies, the rotation direction of the robot is reversed, maintaining a similar magnitude. The transversal speeds at this frequency range, maintain their direction but are clearly reduced compared to lower frequencies.Tesi

Microdevices and Microsystems for Cell Manipulation

Microfabricated devices and systems capable of micromanipulation are well-suited for the manipulation of cells. These technologies are capable of a variety of functions, including cell trapping, cell sorting, cell culturing, and cell surgery, often at single-cell or sub-cellular resolution. These functionalities are achieved through a variety of mechanisms, including mechanical, electrical, magnetic, optical, and thermal forces. The operations that these microdevices and microsystems enable are relevant to many areas of biomedical research, including tissue engineering, cellular therapeutics, drug discovery, and diagnostics. This Special Issue will highlight recent advances in the field of cellular manipulation. Technologies capable of parallel single-cell manipulation are of special interest

Bio-inspired robotic control in underactuation: principles for energy efficacy, dynamic compliance interactions and adaptability.

Biological systems achieve energy efficient and adaptive behaviours through extensive autologous and exogenous compliant interactions. Active dynamic compliances are created and enhanced from musculoskeletal system (joint-space) to external environment (task-space) amongst the underactuated motions. Underactuated systems with viscoelastic property are similar to these biological systems, in that their self-organisation and overall tasks must be achieved by coordinating the subsystems and dynamically interacting with the environment. One important question to raise is: How can we design control systems to achieve efficient locomotion, while adapt to dynamic conditions as the living systems do? In this thesis, a trajectory planning algorithm is developed for underactuated microrobotic systems with bio-inspired self-propulsion and viscoelastic property to achieve synchronized motion in an energy efficient, adaptive and analysable manner. The geometry of the state space of the systems is explicitly utilized, such that a synchronization of the generalized coordinates is achieved in terms of geometric relations along the desired motion trajectory. As a result, the internal dynamics complexity is sufficiently reduced, the dynamic couplings are explicitly characterised, and then the underactuated dynamics are projected onto a hyper-manifold. Following such a reduction and characterization, we arrive at mappings of system compliance and integrable second-order dynamics with the passive degrees of freedom. As such, the issue of trajectory planning is converted into convenient nonlinear geometric analysis and optimal trajectory parameterization. Solutions of the reduced dynamics and the geometric relations can be obtained through an optimal motion trajectory generator. Theoretical background of the proposed approach is presented with rigorous analysis and developed in detail for a particular example. Experimental studies are conducted to verify the effectiveness of the proposed method. Towards compliance interactions with the environment, accurate modelling or prediction of nonlinear friction forces is a nontrivial whilst challenging task. Frictional instabilities are typically required to be eliminated or compensated through efficiently designed controllers. In this work, a prediction and analysis framework is designed for the self-propelled vibro-driven system, whose locomotion greatly relies on the dynamic interactions with the nonlinear frictions. This thesis proposes a combined physics-based and analytical-based approach, in a manner that non-reversible characteristic for static friction, presliding as well as pure sliding regimes are revealed, and the frictional limit boundaries are identified. Nonlinear dynamic analysis and simulation results demonstrate good captions of experimentally observed frictional characteristics, quenching of friction-induced vibrations and satisfaction of energy requirements. The thesis also performs elaborative studies on trajectory tracking. Control schemes are designed and extended for a class of underactuated systems with concrete considerations on uncertainties and disturbances. They include a collocated partial feedback control scheme, and an adaptive variable structure control scheme with an elaborately designed auxiliary control variable. Generically, adaptive control schemes using neural networks are designed to ensure trajectory tracking. Theoretical background of these methods is presented with rigorous analysis and developed in detail for particular examples. The schemes promote the utilization of linear filters in the control input to improve the system robustness. Asymptotic stability and convergence of time-varying reference trajectories for the system dynamics are shown by means of Lyapunov synthesis

Automatic Microassembly System for tissue engineering- Assisted with top-view and force control

Master'sMASTER OF ENGINEERIN