Journal articles, elisabeth smela, professor, mechanical engineering, university of maryland electricity symbols worksheet


Tactile sensing is of interest for facilitating interactions between robots and humans. To aid the robot’s interpretation of human contact, the use of a multilayer cutaneous tactile sensing architecture that can provide more information and an expanded force sensing range was explored, revealing differences in the signal generated by a machine versus a human. The multi-layer system consisted of two stretchable sensing skins alternating with two foam layers of different stiffness. When human touch was compared with machine indentation, a large variability in human touch was found. Thus, although the topmost skin, placed over a soft foam, was able to better recognize light contacts, a second underlying skin, placed over a harder foam, was required to gauge stronger human contacts. Out-of-plane touch modalities, such as tapping and punching, could be identified using strip-shaped skins having just two electrodes. To provide distributed sensing, the technique of electrical impedance tomography was employed with the multi-layer architecture using larger-area skins having electrodes around the perimeter. Distributed touch modalities, such as multi-point finger presses and sliding, were distinguished from single-point pressing. The distributed multi-layer sensing system also had the ability to assess higher-force touches.

To allow robots to interact with humans via touch, new sensing concepts are needed that can detect a wide range of potential interactions and cover the body of a robot. In this paper, a skin-inspired multi-layer tactile sensing architecture is presented and characterized. electricity word search printable The structure consists of stretchable piezoresistive strain-sensing layers over foam layers of different stiffness, allowing for both sufficient sensitivity and pressure range for human contacts. Strip-shaped sensors were used in this architecture to produce a deformation response proportional to pressure. The roles of the foam layers were elucidated by changing their stiffness and thickness, allowing the development of a geometric model to account for indenter interactions with the structure. The advantage of this architecture over other approaches is the ability to easily tune performance by adjusting the stiffness or thickness of the foams to tailor the response for different applications. Since viscoelastic materials were used, the temporal effects were also investigated.

A tactile sensing architecture is presented for detection of surface features that have a particular target size, and the concept is demonstrated with a braille pattern. The approach is akin to an inverse of mechanical profilometry. The sensing structure is constructed by suspending a stretchable strain-sensing membrane over a cavity. The structure is moved over the surface, and a signal is generated through mechanical spatial filtering if a feature is small enough to penetrate into the cavity. gas dryer vs electric dryer hookups This simple design is tailorable and can be realized by standard machining or 3D printing. Images of target features can be produced with even a low-cost compliant sensor. gas efficient suv 2014 In this work a disposable elastomeric piezoresistive strain sensor was used over a cylindrical “finger” part with a groove having a width corresponding to the braille dot size. A model was developed to help understand the working principle and guide finger design, revealing amplification when the cavity matches the feature size. The new sensing concept has the advantages of being easily reconfigured for a variety of sensing problems and retrofitted to a wide range of robotic hands, as well as compatibility with many compliant sensor types.

CMOS chips are increasingly used for direct sensing and interfacing with fluidic and biological systems. However, distinct and vexing technical challenges arise from the disparate requirements of biosensors and integrated circuits. The IC design process must take into account operation at 37 °C, electro-thermal effects and corresponding power limitations, additional floorplanning complexity, signal coupling through fluid, and electrochemical effects. System modeling has to address not only circuit design but also physical structures post-fabricated on the surface of the IC and the behavior of biological components. The next step is packaging, which must enable electrical operation while also allowing fluidic integration for cell culture; for MEMS processing it should ideally provide a flat surface. At the final stage, cell culture on an IC chip requires surface preparation and biocompatible materials. The opacity of the chip presents challenges in optical assessment, while incubator-free cell culture presents its own issues. We recommend a two-step modeling approach to overcome the lack of multi-domain modeling tools: using FEM simulation to determine electro-thermal and electrostatic effects, and using those results to modify simulation parameters for IC design. These simulations can also aid in material selection and in ascertaining layer thicknesses for packaging.

For robots that work collaboratively with people, often referred to as “co-robots”, it would be beneficial for them to be soft or padded and to have a touch-sensing “skin” to enable tactile environmental awareness. However, a sensing skin over a padding material that undergoes large deformations requires “stretchable” materials, which may possess time-dependent or viscoelastic mechanical responses. In this work the roles that a padding layer plays when placed under a stretchable sensing layer was investigated. A strain-sensing skin was formed by coating a thin film of compliant piezoresistive sensing paint, consisting of exfoliated graphite in latex, onto a rubber membrane, and the response of the skin was characterized. The change in resistance was linear with tensile strain. The role of the padding material was then investigated under indentation by examining three foams and two elastomers. As expected, the padding enhanced energy dissipation as shown by hysteresis in the sensor response, which is linked to its protective function; the hysteresis was comparable for the five padding materials. electricity in costa rica The padding also provided an unexpected advantage: it magnified the change in resistance compared to that obtained under free displacement in air. While hysteresis in viscoelastic materials can largely be handled with an appropriate model, inconsistency cannot be, and the two elastomers were found to have unacceptably high variability because of micro-cracks and other defects in these materials. On the other hand, foams that had few defects and regular cell sizes gave good consistency across trials and different sensor positions over the padding. Combined with their lighter weight and availability in a wide range of stiffness, we conclude that foams make a better choice for padding of co-robots.

Because of their fragility, nanostructured surfaces have not been used in applications that requiremechanical contact with the environment. This paper demonstrates the utility of an array of“microbumpers” in the form of pillars rising above a nanostructured surface to provide protection. Super-hydrophobic surfaces with micro-pillar arrays of varying pitch were fabricated and subjected to repeatedvertical touch with a PDMS finger replica under different applied forces, such as would be experiencedby a touch screen display. For sufficiently small pitches, the microbumpers maintained the strong waterrepellency and low droplet adhesion, even after 1000 touch cycles, but if the pitch was too large thenanostructures were damaged and the superhydrophobicity lost. electricity definition wikipedia In comparison, surfaces comprisingonly nanostructures lost superhydrophobicity almost immediately. To image surface wetting by the waterdroplets, a droplet freeze-fixing, resin-embedding (FFRE) technique was developed. The approach of dec-orating a surface with microbumpers to provide mechanical protection should be applicable to a widerange of substrates with coatings optimized for various functions.

A spiral inertial filtration (SIFT) device that is capable of high-throughput (1 ml/min), high-purity particle separation while concentrating recovered target particles by more than an order of magnitude is reported. This device is able to remove large fractions of sample fluid from a microchannel without disruption of concentrated particle streams by taking advantage of particle focusing in inertial spiral microfluidics, which is achieved by balancing inertial lift forces and Dean drag forces. To enable the calculation of channel geometries in the SIFT microsystem for specific concentration factors, an equivalent circuit model was developed and experimentally validated. Large particle concentration factors were then achieved by maintaining either the average fluid velocity or the Dean number throughout the entire length of the channel during the incremental removal of sample fluid. The SIFT device was able to separate MCF7 cells spiked into whole blood from the non-target white blood cells (WBC) with a recovery of nearly 100% while removing 93% of the sample volume, which resulted in a concentration enhancement of the MCF7 cancer cells by a factor of 14.

The development of prognostic and diagnostic biomarkers, such as those from gene expression studies, requires independent validation in clinical specimens. Immunohistochemical analysis on tissue microarrays (TMAs) of formalin-fixed paraffin-embedded tissue is often used to increase the statistical power, and it is used more often than in situ hybridization, which can be technically limiting. Herein, we introduce a method for performing quantitative gene expression analysis across a TMA using an adaptation of 2D-RT-qPCR, a recently developed technology for measuring transcript levels in a histologic section while maintaining 2-dimensional positional information of the tissue sample. As a demonstration of utility, a TMA with tumor and normal human prostate samples was used to validate expression profiles from previous array-based gene discovery studies of prostate cancer. The results show that 2D-RT-qPCR expands the utility of TMAs to include sensitive and accurate gene expression measurements.

Conjugated polymer actuators have potential use in implantable neural interface devices for modulating the position of electrode sites within brain tissue or guiding insertion of neural probes along curved trajectories. c gastronomie vitam The actuation of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) was characterized to ascertain whether it could be employed in the cerebral environment. Microfabricated bilayer beams were electrochemically cycled at either 22 or 37 °C in aqueous NaDBS or in artificial cerebrospinal fluid (aCSF). Nearly all the ions in aCSF were exchanged into the PPy – the cations Na+, K+, Mg2+, Ca2+, as well as the anion PO43-; Cl- was not present. Nevertheless, deflections in aCSF were comparable to those in NaDBS and they were monotonic with oxidation level: strain increased upon reduction, with no reversal of motion despite the mixture of ionic charges and valences being exchanged. Actuation depended on temperature. Upon warming, the cyclic voltammograms showed additional peaks and an increase of 70% in the consumed charge. g gas lol Bending was, however, much less affected: strain increased somewhat (6-13%) but remained monotonic, and deflections shifted (up to 20%). These results show how the actuation environment must be taken into account, and demonstrate proof of concept for actuated implantable neural interfaces.

Combining integrated circuitry with microfluidics enables lab-on-a-chip (LOC) devices to perform sensing, freeing them from benchtop equipment. However, this integration is challenging with small chips, as is briefly reviewed with reference to key metrics for package comparison. In this paper we present a simple packaging method for including mm-sized, foundry-fabricated dies containing complementary metal oxide semiconductor (CMOS) circuits within LOCs. The chip is embedded in an epoxy handle wafer to yield a level, large-area surface, allowing subsequent photolithographic post-processing and microfluidic integration. Electrical connection off-chip is provided by thin film metal traces passivated with Parylene-C. The Parylene is patterned to selectively expose the active sensing area of the chip, allowing direct interaction with a fluidic environment. electricity was invented The method accommodates any die size and automatically levels the die and handle wafer surfaces. Functionality was demonstrated by packaging two different types of CMOS sensor ICs, a bioamplifier chip with an array of surface electrodes connected to internal amplifiers for recording extracellular electrical signals and a capacitance sensor chip for monitoring cell adhesion and viability. Cells were cultured on the surface of both types of chips, and data were acquired using a PC. Long term culture (weeks) showed the packaging materials to be biocompatible. Package lifetime was demonstrated by exposure to fluids over a longer duration (months), and the package was robust enough to allow repeated sterilization and re-use. The ease of fabrication and good performance of this packaging method should allow wide adoption, thereby spurring advances in miniaturized sensing systems.