ADVANCES IN MICROELECTROMECHANICAL SYSTEMS

Microelectromechanical systems (MEMS) are integratedmicrodevices or systems combining electrical and mechanical components. The mechanical microcomponents either move inresponse to certain stimuli (sensors) or are initiated to performcertain tasks (actuators). The microelectronic components areused to control that motion or to obtain information from that motion. These systems can sense, control, actuate, and function individually or in arrays to generate effects on the microscale.These are fabricated using integrated circuit (IC) batch processing techniques making it possible to realise the complete systemon a chip. The miniaturisation of mechanical components bringsthe same benefit to mechanical systems that microfabrication brings to electronics. In a broader sense, technologies associatedwith MEMS include smart materials (e.g. shape memory alloys,ferroelectrics) and processes required to make MEMS components, integration of components to make MEMS devices (sensors,actuators, etc.) and applications that use MEMS devices. The MEMS are considered as building blocks for complex microrobots performing a variety of tasks and are used to make system swhich function very close to biological systems existing in nature.Defence Science Journal, 2009, 59(6), pp.555-556, DOI:http://dx.doi.org/10.14429/dsj.59.157

Inductively Heated Shape Memory Polymer for the Magnetic Actuation of Medical Devices

Submitted to IEEE Trans. Biomed. Eng.Presently there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with Nickel Zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.Lawrence Livermore National Lab

Photonic artificial muscles: From micro robots to tissue engineering

Light responsive shape-changing polymers are able to mimic the function of biological muscles accomplishing mechanical work in response to selected stimuli. A variety of manufacturing techniques and chemical processes can be employed to shape these materials to different length scales, from centimeter fibers and films to 3D printed micrometric objects trying to replicate biological functions and operations. Controlled deformations shown to mimick basic animal operations such as walking, swimming or grabbing objects, while also controlling the refractive index and the geometry of devices, opens up the potential to implement tunable optical properties. Another possibility is that of combining artificial polymers with cells or biological tissue (such as intact cardiac trabeculae) with the aim to improve tissue formation in vitro or to support the mechanical function of damaged biological muscles. Such versatility is afforded by chemistry. New customized liquid crystalline monomers are presented here that modulate material properties for different applications. The role of synthetic material composition is highlighted as we demonstrate how using apparently similar molecular formulations, that liquid crystalline polymers can be adapted to different technological and medical challenges

Elastically and Plastically Foldable Electrothermal Micro‐Origami for Controllable and Rapid Shape Morphing

Integrating origami principles within traditional microfabrication methods can produce shape morphing microscale metamaterials and 3D systems with complex geometries and programmable mechanical properties. However, available micro‐origami systems usually have slow folding speeds, provide few active degrees of freedom, rely on environmental stimuli for actuation, and allow for either elastic or plastic folding but not both. This work introduces an integrated fabrication–design–actuation methodology of an electrothermal micro‐origami system that addresses the above‐mentioned challenges. Controllable and localized Joule heating from electrothermal actuator arrays enables rapid, large‐angle, and reversible elastic folding, while overheating can achieve plastic folding to reprogram the static 3D geometry. Because the proposed micro‐origami do not rely on an environmental stimulus for actuation, they can function in different atmospheric environments and perform controllable multi‐degrees‐of‐freedom shape morphing, allowing them to achieve complex motions and advanced functions. Combining the elastic and plastic folding enables these micro‐origami to first fold plastically into a desired geometry and then fold elastically to perform a function or for enhanced shape morphing. The proposed origami systems are suitable for creating medical devices, metamaterials, and microrobots, where rapid folding and enhanced control are desired.An elastically and plastically foldable micro‐origami is developed and tested to create controllable and functional 3D shape morphing systems with multiple active degrees of freedom. The work demonstrates a versatile design–fabrication–actuation method to achieve rapid folding, enhanced control, and function in different atmospheric environments, enabling applications in microrobots, medical devices, and metamaterials.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163442/2/adfm202003741.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163442/1/adfm202003741-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163442/3/adfm202003741_am.pd

A SHEET OF SOFT MATERIAL IS UTILIZED AS LIVING HINGE, WITHOUT ADDITIONAL MECHANISM WHERE REQUIRES ROTATION FUNCTION

This disclosure relates to detachable notebook, it has softcover to provide the input (keyboard and touch pad) function and protection function. In order to communicate signal between slate to softcover, it needs a connection point located in both devices. The connection point in softcover is required to rotate according to slate\u27s tilting angle. Therefore, the connection point can be connected all the time no matter how it rotates. Usually, a simple hinge mechanism is designed to offer the rotation ability. In this disclose, it eliminates the conventional mechanical hinge structure, but still able to provide the rotation ability, by utilizing the exterior enclosure soft material. It\u27s simply cut in U shape in certain place, the remaining connecting edge become the rotation function provider. Which is called Living Hinge in this case

Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Traditional biped walkers based on passive dynamic walking usually have flat or circular feet. Thisfoot contact may be modelled with an eective rocker - represented as a roll-over shape - to describethe function of the knee-ankle-foot complex in human ambulation. Mahmoodi et al. has representedthis roll-over shape as a polygon with a discretized set of collisions. In this paper point foot, collisionaland smooth rolling contact models are compared. An approach based on the Lagrangian mechanicsare used to formulate the equations for the swing phase that conserves mechanical energy. Qualitativeinsight can be gained by studying the bifurcation diagrams of gait descriptors such as average velocity,step period, mechanical energy and inter-leg angle for dierent gain and length values for the feet,as well as dierent mass and length ratios. The results from the three approaches are compared anddiscussed. In the case of a rolling disk, the collisional contact model gives a negligible energy loss;incorporated into the double inverted pendulum system, however, reveals much greater errors. Thisresearch is not only useful for understanding the stability of bipedal walking, but also for the designof rehabilitative devices such as prosthetic feet and orthoses

Constrained incipient phase transformation in Ni-Mn-Ga films: A small-scale design challenge

Ni-Mn-Ga shape-memory alloys are promising candidates for large strain actuation and magnetocaloric cooling devices. In view of potential small-scale applications, we probe here nanomechanically the stress-induced austenite–martensite transition in single crystalline austenitic thin films as a function of temperature. In 0.5 µm thin films, a marked incipient phase transformation to martensite is observed during nanoindentation, leaving behind pockets of residual martensite after unloading. These nanomechanical instabilities occur irrespective of deformation rate and temperature, are Weibull distributed, and reveal large spatial variations in transformation stress. In contrast, at a larger film thickness of 2 μm fully reversible transformations occur, and mechanical loading remains entirely smooth. Ab-initio simulations demonstrate how an in-plane constraint can considerably increase the martensitic transformation stress, explaining the thickness-dependent nanomechanical behavior. These findings for a shape-memory Heusler alloy give insights into how reduced dimensions and constraints can lead to unexpectedly large transformation stresses that need to be considered in small-scale actuation design

Intracellular Mechanical Drugs Induce Cell-Cycle Altering and Cell Death

Current advances in materials science have demonstrated that extracellular mechanical cues can define cell function and cell fate. However, a fundamental understanding of the manner in which intracellular mechanical cues affect cell mechanics remains elusive. How intracellular mechanical hindrance, reinforcement, and supports interfere with the cell cycle and promote cell death is described here. Reproducible devices with highly controlled size, shape, and with a broad range of stiffness are internalized in HeLa cells. Once inside, they induce characteristic cell-cycle deviations and promote cell death. Device shape and stiffness are the dominant determinants of mechanical impairment. Device structural support to the cell membrane and centering during mitosis maximize their effects, preventing spindle centering, and correct chromosome alignment. Nanodevices reveal that the spindle generates forces larger than 114 nN which overcomes intracellular confinement by relocating the device to a less damaging position. By using intracellular mechanical drugs, this work provides a foundation to defining the role of intracellular constraints on cell function and fate, with relevance to fundamental cell mechanics and nanomedicine.Peer reviewe