Reza Saeidpourazar

Design and Development of

This paper presents the development of H∞ and μ-synthesis robust controllers for nanorobotic manipulation and grasping applications. Here a 3 DOF (Degrees Of Freedom) nanomanipulator with RRP (Revolute Revolute Prismatic) actuator arrangement is considered for nanomanipulation purposes. Due to the sophisticated complexity, and expected high level of accuracy and precision (of the order of 10−7 rad in revolute actuators and 0.25 nm in the prismatic actuator) of the nanomanipulator, there is a need to design a suitable controller to guarantee an accurate manipulation process. However, structure of the nanomanipulator employed here, namely MM3A, is such that the dynamic equations of motion of the nanomanipulator are highly nonlinear and complicated. Linearizing these dynamic equations of the nanomanipulator simplifies the controller design process significantly. However, linearization could suppress some critical information about the system dynamics. In order to achieve the precise motion of the nanomanipulator utilizing the simple linearized model, H∞ and μ-synthesis robust controller design approaches are proposed. Following the development of the controllers, numerical simulations of the proposed controllers on the nanomanipulator are used to verify the positioning performance.Copyright

Laser-Driven Micro Transfer Placement of Prefabricated Microstructures

Microassembly of prefabricated structures and devices is emerging as key process technology for realizing heterogeneous integration and high-performance flexible and stretchable electronics. Here, we report on a laser-driven micro transfer placement process that exploits, instead of ablation, the mismatch in thermomechanical response at the interface of a transferable microstructure and a transfer tool to a laser pulse to drive the release of the microstructure from the transfer tool and its travel to a receiving substrate. The resulting facile pick-and-place process is demonstrated with the assembling of 3-D microstructures and the placement of GaN light-emitting diodes onto silicon and glass substrates. High-speed photography is used to provide experimental evidence of thermomechanically driven release. Experiments are used to measure the laser flux incident on the interface. These, when used in numerical and analytical models, suggest that temperatures reached during the process are enough to produce strain energy release rates to drive delamination of the microstructure from the transfer tool.

Towards Microcantilever-based Force Sensing and Manipulation: Modeling, Control Development and Implementation

This paper presents a distributed-parameters-based modeling framework for piezoresistive microcantilever (MC)-based force sensors used in a variety of cantilever-based nanomanipulation processes. Current modeling practices call for a simple lumped-parameters approach rather than modeling the piezoresistive MC itself. Owing to the widespread applications of such MCs in nanoscale force sensing or non-contact atomic force microscopy with nano-Newton to pico-Newton force measurement requirements, precise modeling of the piezoresistive MCs is essential. Instead of the previously used lumped-parameters modeling, a distributed-parameters modeling framework is proposed and developed here to arrive at the most complete model of the piezoresistive MC including tip-mass, tip-force and base movement considerations. In order to have online control and real-time sensor feedback, a closed-form model of the piezoresistive MC, which expresses the MCs piezoresistive output voltage as a function of tip force and base motion, is highly desirable. Along this line of reasoning, a closed-form model for the piezoresistive MC is presented. Following mathematical modeling, both numerical simulations and experimental results are presented to demonstrate the accuracy of the proposed distributed-parameters model when compared with the previously reported lumped-parameters modeling approach. Utilizing the developed model, a modified robust controller with perturbation estimation is adopted to target the problem of slow imaging acquisition and manipulation at the nanoscale. It is shown that the proposed controller can stabilize such nanomanipulation process in less than a second. Experimental results are presented to demonstrate the stability and performance characteristics of the designed controller. Such modeling and control development could pave the way for MC-based nanomanipulation and nanopositioning.

Nano-robotic manipulation using a RRP nanomanipulator: Part A – Mathematical modeling and development of a robust adaptive driving mechanism

A three degree of freedom (3 DOF) nanomanipulator with revolute revolute prismatic (RRP) actuator structure, named here MM3A, can be utilized for a variety of nanomanipulation tasks. This first paper in the series presents the mathematical modeling and development of a memory-based robust adaptive controller for the nanomanipulator driving principle. Unlike widely used Cartesian-structure nanomanipulators, the MM3A is equipped with revolute-piezoelectric actuators which result in outstanding performance in controlling the nanomanipulators tip alignment during the nanomanipulation. However, the RRP structure of the nanomanipulator introduces complexity in kinematic and dynamic equations of the system which needs to be addressed in order to control the nanomanipulation process. Dissimilar to the ordinary piezoelectric actuators which provide only a couple of micrometers working range, the piezoelectric actuators utilized in MM3A, namely Nanomotors®, provide wide range of action (120° in revolute actuators and 12 mm in prismatic actuator) with nanoscale precision (0.1 μrad in revolute actuators and 0.25 nm in prismatic actuator). This wide range of action combined with nanoscale precision is achieved using a special stick/slip moving principle of the Nanomotors®. However, such stick/slip motion results in stepping movement of the MM3A. Hence, due to the RRP structure and stepping movement principle of the MM3A nanomanipulator, development and implementation of an appropriate controller for such nanomanipulation process is not a trivial task. In this paper, a novel memory-based robust adaptive controller is proposed to overcome such shortfalls. Following the development the controller, numerical simulations are preformed to demonstrate the positioning performance capability of the controller in a variety of nanomanipulation tasks.

Nano-robotic manipulation using a RRP nanomanipulator: Part B -Robust control of manipulator's tip using fused visual servoing and force sensor feedbacks

Due to lack of position and velocity feedbacks in MM3A nanomanipulator, a fused vision/ force feedback robust controller has been recently designed by the authors. This second paper in the series presents the optimal utilization of the visual servoing and force sensor feedbacks for use in the nanomanipulation tasks discussed in the first paper (Part A). More specifically, the visual servoing and force feedback structures are investigated through extensive simulations in order to reveal issues in practical implementation. For this, a set of numerical simulations is performed to demonstrate the effectiveness of utilizing just vision feedback as well as force feedback only, at both macro and microscale. It is shown that although each feedback module could provide reasonably accurate results at either macro or microscale, precise positioning of such nanomanipulator requires employment of both modules with a proper (optimal) switching strategy. This paper extends our previously introduced robust controller for nanomanipulator positioning and offers a novel switching framework to be used between vision feedback and force feedback modules. Utilizing a soft switching function, the problem of jump in the actuator force during fused vision/force control of the nanomanipulation can be overcome. Following the development of the soft switching approach, numerical simulations are used to verify the positioning performance and effectiveness of each switching strategy.

Adhesin-Specific Nanomechanical Cantilever Biosensors for Detection of Microorganisms

Lectins (adhesins) on bacterial surfaces play important roles in infection by mediating bacterial adherence to host cell surfaces via their cognate receptors. We have explored the use of α-D-mannose receptors as capturing agents for the detection of Escherichia coli using a microcantilever and have demonstrated that E. coli ORN178, which expresses normal type-1 pili, can interact with microcantilevers functionalized with α-D-mannose and can cause shifts in its resonance frequencies. Although E. coli ORN208, which expresses abnormal pili, binds poorly to α-D-mannose on the nitrocellulose membrane of a FAST slide, it did cause a detectable shift in resonance frequency when interacting with the α-D-mannose functionalized microcantilevers.

Development, analysis and control of a high-speed laser-free atomic force microscope

This paper presents the development and control of a laser-free atomic force microscopy (AFM) system for high-speed imaging of micro- and nanostructured materials. The setup uses a self-sensing piezoresistive microcantilever with nanometer accuracy to abolish the need for a bulky and expensive laser measurement system. A basic model for the interaction dynamics of AFM tip and sample in the high-speed open-loop imaging mode is proposed, accounting for their possible separation. The effects of microcantilever and sample stiffness and damping coefficients on the accuracy of imaging are studied through a set of frequency-domain simulations. To improve the speed of operation, a Lyapunov-based robust adaptive control law is used for the AFM XY scanning stage. It is shown that the proposed controller overcomes the frequency limits of the PID (Proportional-Integral-Derivative) controllers typically used in AFM. Finally, the paper presents a set of experiments on a standard calibration sample with 200 nm stepped topography, indicating accurate imaging up to the scanning frequency of 30 Hz.

Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing

An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated receiving substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments.

New modeling and control framework for MEMS characterization utilizing piezoresistive microcantilever sensors

This paper presents a comprehensive modeling and control framework for characterizing MEMS utilizing piezoresistive microcantilevers. These microcantilevers have recently received widespread attention due to their extreme sensitivity and simplicity in a variety of sensing applications. Most of the current studies; however, focus on a simple lumped-parameters representation rather than modeling the piezoresistive microcantilever itself. Due to the applications of the piezoresistive microcantilevers in nanoscale force sensing or non-contact atomic force microscopy with nano-Newton to pico-Newton range force measurement requirement, precise modeling of the piezoresistive microcantilevers is essential. For this, a distributed-parameters modeling is proposed and developed here to arrive at the most complete model of the piezoresistive microcantilever with tip-mass, tip-force and base movement considerations. In order to have online control and real-time sensor feedback, an inverse model of piezoresistive microcantilever is needed which utilizes the output voltage of the piezoresistive layer as well as the base motion information to predict the force acting on the microcantilevers tip. Utilizing a novel approach, an inverse modeling framework and control algorithm are then proposed for the characterization of MEMS utilizing piezoresistive microcantilevers. Following the mathematical modeling and controller design, both numerical simulations and experimental results are presented to demonstrate the accuracy of the proposed distributed- parameters modeling when compared with the previously reported lumped-parameters approach. It is shown that by utilizing the distributed-parameters model rather than lumped-parameters approach and by predicting the exact motion of each point on the microcantilever, the precision of the piezoresistive microcantilevers model is significantly enhanced.

Modeling and Observer-Based Robust Tracking Control of a Nano/Micro-Manipulator for Nanofiber Grasping Applications

This paper presents the modeling and control of a nano/micro-manipulator for use in nano-fiber grasping and nano-fabric production. The RRP (Revolute-Revolute-Prismatic) manipulator considered here utilizes two rotational motors with 10-7 rad resolution and one linear Nanomotor® with 0.25nm resolution. Weighing just 30g and having short lever arms (<5cm), the manipulator is capable of achieving well-behaved kinematic characteristics without backlash and with atomic scale precision to guarantee accurate manipulation at nanoscale. A mathematical model of the micromanipulator is formulated and both direct and inverse kinematics of the system as well as dynamic equations are presented. Several controllers for manipulator positioning tracking are derived and analyzed extensively. Unlike typical macroscale manipulator models and controllers, the controller development is not trivial due to nanoscale movement and forces, coupled with unmodeled dynamics and nonlinear structural dynamics. Following the development of the controllers, numerical simulations of the proposed controllers on the manipulator are used to verify the tracking performance.Copyright