Workshop on "Robotic assembly of 3D MEMS".

Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary

Hybrid optical and magnetic manipulation of microrobots

Microrobotic systems have the potential to provide precise manipulation on cellular level for diagnostics, drug delivery and surgical interventions. These systems vary from tethered to untethered microrobots with sizes below a micrometer to a few microns. However, their main disadvantage is that they do not have the same capabilities in terms of degrees-of-freedom, sensing and control as macroscale robotic systems. In particular, their lack of on-board sensing for pose or force feedback, their control methods and interface for automated or manual user control are limited as well as their geometry has few degrees-of-freedom making three-dimensional manipulation more challenging. This PhD project is on the development of a micromanipulation framework that can be used for single cell analysis using the Optical Tweezers as well as a combination of optical trapping and magnetic actuation for recon gurable microassembly. The focus is on untethered microrobots with sizes up to a few tens of microns that can be used in enclosed environments for ex vivo and in vitro medical applications. The work presented investigates the following aspects of microrobots for single cell analysis: i) The microfabrication procedure and design considerations that are taken into account in order to fabricate components for three-dimensional micromanipulation and microassembly, ii) vision-based methods to provide 6-degree-offreedom position and orientation feedback which is essential for closed-loop control, iii) manual and shared control manipulation methodologies that take into account the user input for multiple microrobot or three-dimensional microstructure manipulation and iv) a methodology for recon gurable microassembly combining the Optical Tweezers with magnetic actuation into a hybrid method of actuation for microassembly.Open Acces

PLANNING FOR AUTOMATED OPTICAL MICROMANIPULATION OF BIOLOGICAL CELLS

Optical tweezers (OT) can be viewed as a robot that uses a highly focused laser beam for precise manipulation of biological objects and dielectric beads at micro-scale. Using holographic optical tweezers (HOT) multiple optical traps can be created to allow several operations in parallel. Moreover, due to the non-contact nature of manipulation OT can be potentially integrated with other manipulation techniques (e.g. microfluidics, acoustics, magnetics etc.) to ensure its high throughput. However, biological manipulation using OT suffers from two serious drawbacks: (1) slow manipulation due to manual operation and (2) severe effects on cell viability due to direct exposure of laser. This dissertation explores the problem of autonomous OT based cell manipulation in the light of addressing the two aforementioned limitations. Microfluidic devices are well suited for the study of biological objects because of their high throughput. Integrating microfluidics with OT provides precise position control as well as high throughput. An automated, physics-aware, planning approach is developed for fast transport of cells in OT assisted microfluidic chambers. The heuristic based planner employs a specific cost function for searching over a novel state-action space representation. The effectiveness of the planning algorithm is demonstrated using both simulation and physical experiments in microfluidic-optical tweezers hybrid manipulation setup. An indirect manipulation approach is developed for preventing cells from high intensity laser. Optically trapped inert microspheres are used for manipulating cells indirectly either by gripping or pushing. A novel planning and control approach is devised to automate the indirect manipulation of cells. The planning algorithm takes the motion constraints of the gripper or pushing formation into account to minimize the manipulation time. Two different types of cells (Saccharomyces cerevisiae and Dictyostelium discoideum) are manipulated to demonstrate the effectiveness of the indirect manipulation approach

Nanoscale Magnetometry with Single Fluorescent Nanodiamonds Manipulated in an Anti-Brownian Electrokinetic Trap

Studies on single-molecule spectroscopy and nanoscale detection have been remarkably driven by an interest to reveal quantum and conformational states of single particles, the intra-molecular dynamics and their response to physical observables hidden by ensemble level measurements. A straightforward practice used in enhancing the signal from single particles is either to immobilize them on an engineered substrate or to embed them in a solid matrix. Given that the biophysical properties of the host environment introduce new perturbations and the particles will not behave as in their native environment, such approaches are inefficient to reflect the real dynamics. Therefore, recent advances in the field of single-molecule have led to a renewed interest in novel trapping methods, increased efforts into the development of promising tools for extended investigation, and the manipulation of solution-phase bio-molecules in real time. Despite the variety of successful passive trapping techniques, precise manipulation through non-perturbative forces is a big challenge for nano-sized particles. Such techniques either exert high power to the sample or compel special operating conditions disturbing the native environment. Therefore, an active trapping scheme guiding non-perturbative forces can break the trade-off between the particle size and the excreted power. This dissertation presents the development of an active trapping set-up using non-perturbative electrokinetic feedback and demonstrates its performance on nano-sized single particles for aims in biophysics. The essential theme is the engineering aspect of the technique, including the feedback configurations for various fluidic devices, the corresponding particle tracking schemes and the integration of the trapping platform to an integrated circuit pattern for advanced manipulation aims. The second theme is on specialized single fluorescence nanodiamonds (FNDs) as scanning magnetometer in fluidics. The implemented active trapping tool is employed for the manipulation of a rotationally free single FND to detect the localized magnetic field through an optically detected magnetic resonance (ODMR) spectrum. While the laser beam used in particle tracking can serve in optical excitation, an external radio frequency (RF) source is not sufficient to achieve microwave manipulation. Therefore, an RF antenna is designed to transmit the microwave signal to the proximity of the trapping chamber for electron spin resonance (ESR) spectroscopy. A nanostage positioning controller introduces scanning ability to the sample plane, in relative position of the trapped particle, in order to map the distribution of the detected fields over a fluidic volume. As FNDs are also sensitive to many other physical quantities, nanoscale single particle trapping and diamond photonics linkages are realized in this work, which provide an outstanding alternative for detection and imaging in complex fluidic environments that are closed to AFM-like physically supported probes

From nanoscopic to macroscopic photo-driven motion in azobenzene-containing materials

AbstractThe illumination of azobenzene molecules with UV/visible light efficiently converts the molecules between trans and cis isomerization states. Isomerization is accompanied by a large photo-induced molecular motion, which is able to significantly affect the physical and chemical properties of the materials in which they are incorporated. In some material systems, the nanoscopic structural movement of the isomerizing azobenzene molecules can be even propagated at macroscopic spatial scales. Reversible large-scale superficial photo-patterning and mechanical photo-actuation are efficiently achieved in azobenzene-containing glassy materials and liquid crystalline elastomers, respectively. This review covers several aspects related to the phenomenology and the applications of the light-driven macroscopic effects observed in these two classes of azomaterials, highlighting many of the possibilities they offer in different fields of science, like photonics, biology, surface engineering and robotics

Momentum exchange between light and nanostructured matter

An object\u27s translational and rotational motion is associated with linear and angular momenta. When multiple objects interact the exchange of momentum dictates the new system\u27s motion. Since light, despite being massless, carries both linear and angular momentum it too can partake in this momentum exchange and mechanically affect matter in tangible ways. Due to conservation of momentum, any such exchange must be reciprocal, and the light therefore acquires an opposing momentum component. Hence, light and matter are inextricably connected and one can be manipulated to induce interesting effects to the other. Naturally, any such effect is facilitated by having strongly enhanced light-matter interaction, which for visible light is something that is obtained when nanostructured matter supports optical resonances. This thesis explores this reciprocal relationship and how nanostructured matter can be utilised to augment these phenomena.Once focused by a strong lens, light can form optical tweezers which through optical forces and torques can confine and manipulate small particles in space. Metallic nanorods trapped in two dimensions against a cover glass can receive enough angular momentum from circularly polarised light to rotate with frequencies of several tens of kilohertz. In the first paper of this thesis, the photothermal effects associated with such optical rotations are studied to observe elevated thermal environments and morphological changes to the nanorod. Moreover, to elucidate upon the interactions between the trapped particle and the nearby glass surface, in the thesis\u27 second paper a study is conducted to quantify the separation distance between the two under different trapping conditions. The particle is found to be confined ~30-90 nm away from the surface.The momentum exchange from a single nanoparticle to a light beam is negligible. However, by tailoring the response of an array of nanoparticles, phase-gradient metasurfaces can be constructed that collectively and controllably alter the incoming light\u27s momentum in a macroscopically significant way, potentially enabling a paradigm shift to flat optical components. In the thesis\u27 third paper, a novel fabrication technique to build such metasurfaces in a patternable polymer resist is investigated. The technique is shown to produce efficient, large-scale, potentially flexible, substrate-independent flat optical devices with reduced fabricational complexity, required time, and cost.At present, optical metasurfaces are commonly viewed as stationary objects that manipulate light just like common optical components, but do not themselves react to the light\u27s changed momentum. In the last paper of this thesis, it is realised that this is an overlooked potential source of optical force and torque. By incorporating a beam-steering metasurface into a microparticle, a new type of nanoscopic robot – a metavehicle – is invented. Its propulsion and steering are based on metasurface-induced optical momentum transfer and the metavehicle is shown to be driven in complex shapes even while transporting microscopic cargo

Engineering 4D regulation toolbox to control spatiotemporal cell-free reconstitution

Bottom-up reconstituting well-characterized functional molecular entities, parts and modules towards a synthetic cell will give new insights into the general mechanisms and molecular origins of life. However, a remaining central challenge is how to organize cellular processes spatiotemporally from their component parts in vitro. To this end, we developed a 4D regulation toolbox to facilitate a bottom-up reconstitution in both time and space. The spatiotemporal regulation of the 4D toolbox covers the aspects from dynamic gene transcription & translation, reversible protein interaction, spatially protein positioning, sequential protein assembly, extends to defining geometrical membrane boundaries and mimicking cellular anisotropic microenvironment. Firstly, we developed a thermo-genetic regulation toolbox based on synthetic RNA thermometers, for temporally controlling protein expression in vitro. We validated RNA thermometers from in vivo to in vitro and tuned RNA thermometers through utilizing cell free protein synthesis system. Then we generated the thermo-sensitive protocell by encapsulating thermo-regulated transcription and translation machine in water-in-oil droplets. With the temperature sensing devices, the protocells can be operated with logic AND gates, differentially processing temperature stimuli into biological signals. Secondly, we engineered the PhyB-PIF6 system to spatiotemporally target proteins by light onto model membranes and thus sequentially guide protein pattern formation and structural assembly in vitro from the bottom up. We show that complex micrometer-sized protein patterns can be printed on timescales of seconds. Moreover, when printing self-assembling proteins such as the bacterial cytoskeleton protein FtsZ, the targeted assembly into filaments and large-scale structures such as artificial rings can be accomplished. To develop an artificial anisotropic membrane environment, we introduced a 3D printed protein hydrogel device to induce pH-stimulated reversible shape changes in trapped vesicles. Deformations towards unusual quadratic or triangular shapes can be accomplished. Mechanical force induced by the cages to phase-separated membrane vesicles can lead to spontaneous shape deformations. Moreover, the shape-tunable vesicle provides a spatially well-defined microenvironment for reconstituting shape-dependent protein systems, such as reaction-diffusion system that request explicitly non-spherical geometries. By taking advantages of the 3D printed hydrogel, we programmably engineered contractible scaffolds for actin-myosin motor reconstitution in 3D space. Nanoscale actomyosin motor as a bio-actuator could generate, transmit active contraction and then drive large-scale shape-morphing of complex 3D hydrogel scaffolds. In summary, by developing the spatiotemporal toolbox, this thesis introduces a promising step towards establishing bottom-up reconstitution in space and time, which could also guide future efforts in hierarchically building up the next level of complexity towards a minimal cell

Engineering 4D regulation toolbox to control spatiotemporal cell-free reconstitution

Bottom-up reconstituting well-characterized functional molecular entities, parts and modules towards a synthetic cell will give new insights into the general mechanisms and molecular origins of life. However, a remaining central challenge is how to organize cellular processes spatiotemporally from their component parts in vitro. To this end, we developed a 4D regulation toolbox to facilitate a bottom-up reconstitution in both time and space. The spatiotemporal regulation of the 4D toolbox covers the aspects from dynamic gene transcription & translation, reversible protein interaction, spatially protein positioning, sequential protein assembly, extends to defining geometrical membrane boundaries and mimicking cellular anisotropic microenvironment. Firstly, we developed a thermo-genetic regulation toolbox based on synthetic RNA thermometers, for temporally controlling protein expression in vitro. We validated RNA thermometers from in vivo to in vitro and tuned RNA thermometers through utilizing cell free protein synthesis system. Then we generated the thermo-sensitive protocell by encapsulating thermo-regulated transcription and translation machine in water-in-oil droplets. With the temperature sensing devices, the protocells can be operated with logic AND gates, differentially processing temperature stimuli into biological signals. Secondly, we engineered the PhyB-PIF6 system to spatiotemporally target proteins by light onto model membranes and thus sequentially guide protein pattern formation and structural assembly in vitro from the bottom up. We show that complex micrometer-sized protein patterns can be printed on timescales of seconds. Moreover, when printing self-assembling proteins such as the bacterial cytoskeleton protein FtsZ, the targeted assembly into filaments and large-scale structures such as artificial rings can be accomplished. To develop an artificial anisotropic membrane environment, we introduced a 3D printed protein hydrogel device to induce pH-stimulated reversible shape changes in trapped vesicles. Deformations towards unusual quadratic or triangular shapes can be accomplished. Mechanical force induced by the cages to phase-separated membrane vesicles can lead to spontaneous shape deformations. Moreover, the shape-tunable vesicle provides a spatially well-defined microenvironment for reconstituting shape-dependent protein systems, such as reaction-diffusion system that request explicitly non-spherical geometries. By taking advantages of the 3D printed hydrogel, we programmably engineered contractible scaffolds for actin-myosin motor reconstitution in 3D space. Nanoscale actomyosin motor as a bio-actuator could generate, transmit active contraction and then drive large-scale shape-morphing of complex 3D hydrogel scaffolds. In summary, by developing the spatiotemporal toolbox, this thesis introduces a promising step towards establishing bottom-up reconstitution in space and time, which could also guide future efforts in hierarchically building up the next level of complexity towards a minimal cell