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Wireless endovascular sensors and stimulators are emerging biomedical technologies for applications such as endovascular pressure monitoring, hyperthermia, and neural stimulations. Recently, coil-shaped stents have been proposed for inductive power transfer to endovascular devices using the stent as a receiver. However, less work has been done on the external transmitter components, so the maximum power transferable remains unknown. In this work, we design and evaluate a wearable transmitter coil that allows 50 mW power transfer in simulation.Clinical Relevance-This allows more accurate measurements and precise control of endovascular devices.

High-level synthesis (HLS) allows hardware designers to think algorithmically and not worry about low-level, cycle-by-cycle details. This provides the ability to quickly explore the architectural design space and tradeoffs between resource utilization and performance. Unfortunately, security evaluation is not a standard part of the HLS design flow. In this article, we aim to understand the effects of memory-based HLS optimizations on power side-channel leakage. We use Xilinx Vivado HLS to develop different cryptographic cores, implement them on a Spartan-6 FPGA, and collect power traces. We evaluate the designs with respect to resource utilization, performance, and information leakage through power consumption. We have two important observations and contributions. First, the choice of resource optimization directive results in different levels of side-channel vulnerabilities. Second, the partitioning optimization directive can greatly compromise the hardware cryptographic system through power side-channel leakage due to the deployment of memory control logic. We describe an evaluation procedure for power side-channel leakage and use it to make best-effort recommendations about how to design more secure architectures in the cryptographic domain.

Integration of flood risk in spatial planning is increasingly seen as a way to enhance cities’ resilience to the growing flood hazards, albeit its operationalisation remains challenging. This study aims to explain the reasons for this difficulty through the case study of Guangzhou, a Chinese delta city that is highly vulnerable to coastal, fluvial and pluvial flooding, particularly in the context of a changing climate and rapid expansion of the urban fabric. It does so by investigating the recognition of flood risk in spatial planning and vice-versa, of spatial issues in the flood risk management field, using framing analysis. The paper reveals that the integration of flood risk concerns in spatial planning in Guangzhou remains an emerging process, gradually shifting from informal to formal activities grounded in legislation. This happens through percolation of framing discourse from the flood risk management policy to spatial planning, leading to changes in problem setting, action scripts and the prescribed governance arrangements in the planning discourse. The vagueness of governance arrangements, however, undermines the integration of flood risk management in spatial planning., Spatial Planning and Strategy, OLD Urban Compositions

Here we report on the production of highly gas permeable Parylene HT through a cryogenic deposition process. The unique combination of biological and chemical inertness of Parylene, and gas permeability of this porous variant make it interesting for cell culture and biology-on-a-chip applications. The dependence of porosity, density, and permeability on the deposition temperature allows for tunable control of material properties. Culture of HEK-293 cells on cryogenically deposited Parylene HT demonstrates viability for biological applications.

Integration of flood risk in spatial planning is increasingly seen as a way to enhance cities’ resilience to the growing flood hazards, albeit its operationalisation remains challenging. This study aims to explain the reasons for this difficulty through the case study of Guangzhou, a Chinese delta city that is highly vulnerable to coastal, fluvial and pluvial flooding, particularly in the context of a changing climate and rapid expansion of the urban fabric. It does so by investigating the recognition of flood risk in spatial planning and vice-versa, of spatial issues in the flood risk management field, using framing analysis. The paper reveals that the integration of flood risk concerns in spatial planning in Guangzhou remains an emerging process, gradually shifting from informal to formal activities grounded in legislation. This happens through percolation of framing discourse from the flood risk management policy to spatial planning, leading to changes in problem setting, action scripts and the prescribed governance arrangements in the planning discourse. The vagueness of governance arrangements, however, undermines the integration of flood risk management in spatial planning., Spatial Planning and Strategy, OLD Urban Compositions

The virtual training of primitive surgical procedures has been widely recognized as immersive and effective to medical education. Virtual basic surgical training framework integrated with multi-sensations rendering has been recognized as one of the most immersive implementations in medical education. Yet, compared with the original intraoperative data, there has always been an argument on the lower fidelity these data are represented in virtual surgical training. In this paper, a solution is proposed to achieve better training immersion by incorporating multiple higher-fidelity factors toward a trainee's sensations (vision, touch, and hearing) during virtual training sessions. This was based on the proposal of a three-tier model to classify reasons leading to fidelity issues. This include: haptic factors, such as high-quality fitting of force models based on surgical data acquisition, the use of actual surgical instrument linked to desktop haptic devices; visual factors, such as patient-specific CT images segmentation and reconstruction from the original medical data; and hearing factors, such as variations of the sound of monitoring systems in the theatre under different surgical conditions. Twenty seven urologists comprising 18 novices and 9 professors were invited to test a virtual training system based on the proposed solution. Post-test values from both professors' and novices' groups demonstrated obvious improvements in comparison with pre-test values under both the subjective and objective criteria, the fitting rate of the whole puncture processing is 99.93%. Both the subjective and objective results demonstrated a higher performance than the existing benchmark training platform. Combining these in a systematic approach, tuned with specific fidelity requirements, haptically enabled training simulation systems would be able to provide a more immersive and effective training environment.

Delta cities worldwide are confronted with great challenges concerning flood risks, environmental pressures and other water-related urban issues. The complexity in both physical and social dimensions lies in diverse (and in many cases conflicting) values held by a wide variety of actors in spatial development. These values are shaped by the long-term impacts of natural forces, political powers, development ideologies, economic models, social structures, and local cultures. Defining the central role of “water” in structuring delta cities, this research applies the value concept as a particular lens to study how water is valued in each society through history. It argues that the recognition of diverse water values can help bridge the interplay between physical and societal systems within the delta, which can play a central role in developing urban planning and design strategies towards sustainable and liveable urban water environments., A+BE | Architecture and the Built Environment No 20 (2018), OLD Urban Compositions

Cryptographic cores are known to leak information about their private key due to runtime variations, and there are many well-known attacks that can exploit this timing channel. In this paper, we study how information theoretic measures can quantify the amount of key leakage that can be exacted from runtime measurements. We develop and analyze 22 Rivest-Shamir-Adleman (RSA) hardware designs - each with unique performance optimizations, timing channel mitigation techniques, or discretization/randomization countermeasures. We demonstrate the effectiveness of information theoretic measures for quantifying timing leakage through correlation analysis of information theoretic measurements and attack results. Experimental results show that mutual information is a promising technique for quantifying timing leakage for RSA, advanced encryption standard, and elliptic curve cryptography ciphers, i.e., the mutual information correlates to being able to successfully guess the value of the private key. This is an important step toward a hardware security metric which allows designers to reason about security alongside traditional hardware design metrics like area, performance, and power.

Delta cities worldwide are confronted with great challenges concerning flood risks, environmental pressures and other water-related urban issues. The complexity in both physical and social dimensions lies in diverse (and in many cases conflicting) values held by a wide variety of actors in spatial development. These values are shaped by the long-term impacts of natural forces, political powers, development ideologies, economic models, social structures, and local cultures. Defining the central role of “water” in structuring delta cities, this research applies the value concept as a particular lens to study how water is valued in each society through history. It argues that the recognition of diverse water values can help bridge the interplay between physical and societal systems within the delta, which can play a central role in developing urban planning and design strategies towards sustainable and liveable urban water environments., A+BE | Architecture and the Built Environment No 20 (2018), OLD Urban Compositions

We use the non-Cartesian, topography-based equations of mass and momentum balance for gravity driven frictional flows of Luca etal. (Math. Mod. Meth. Appl. Sci. 19, 127-171 (2009)) to motivate a study on various approximations of avalanche models for single-phase granular materials. By introducing scaling approximations we develop a hierarchy of model equations which differ by degrees in shallowness, basal curvature, peculiarity of constitutive formulation (non-Newtonian viscous fluids, Savage-Hutter model) and velocity profile parametrization. An interesting result is that differences due to the constitutive behaviour are largely eliminated by scaling approximations. Emphasis is on avalanche flows; however, most equations presented here can be used in the dynamics of other thin films on arbitrary surfaces

Hardware has become an increasingly attractive target for attackers, yet we still largely lack tools that enable us to analyze large designs for security flaws. Information flow tracking (IFT) models provide an approach to verifying a hardware design's adherence to security properties related to isolation and reachability. However, existing precise IFT models are usually too complex to actually use. Queries may fail to finish even for small designs when verifying relatively simple properties. It is possible to create less complex models, but these come at the cost of a severe loss of precision - -they frequently indicate a property fails when in fact it passes, which means verification requires extensive additional manual investigation. We present a new method to bridge the chasm between precision and complexity in a finer-grained, controlled, and disciplined manner. Our method allows using the most appropriate precision/complexity tradeoff for the design size and available computing resources, meaning it is now possible to create models that are not too complex to be usable, but which offer more precision (fewer false positives) than was previously possible.

Hardware has become an increasingly attractive target for attackers, yet we still largely lack tools that enable us to analyze large designs for security flaws. Information flow tracking (IFT) models provide an approach to verifying a hardware design's adherence to security properties related to isolation and reachability. However, existing precise IFT models are usually too complex to actually use. Queries may fail to finish even for small designs when verifying relatively simple properties. It is possible to create less complex models, but these come at the cost of a severe loss of precision - -they frequently indicate a property fails when in fact it passes, which means verification requires extensive additional manual investigation. We present a new method to bridge the chasm between precision and complexity in a finer-grained, controlled, and disciplined manner. Our method allows using the most appropriate precision/complexity tradeoff for the design size and available computing resources, meaning it is now possible to create models that are not too complex to be usable, but which offer more precision (fewer false positives) than was previously possible.

In this study, the aerodynamic characteristics of the complex air flows acting on a large cont iner ship model are numerically investigated by using a commercial CFD code. The main target is to reduce the air resistance in oblique winds, especially at the small angle of wind directions. Some container side-covers with different size and location are developed to shut the gap flow, and a center wall is also applied. The numerical results show that the air resistance at 30degrees of wind direction can be reduced significantly up to 50%, 30% and 15% by full side-covers, front-half side-covers and lower front-half side-cover, respectively.

MicroPET II is a second-generation animal PET scanner designed for high-resolution imaging of small laboratory rodents. The system consists of 90 scintillation detector modules arranged in three contiguous axial rings with a ring diameter of 16.0 cm and an axial length of 4.9 cm. Each detector module consists of a 14 x 14 array of lutetium oxyorthosilicate (LSO) crystals coupled to a multi-channel photomultiplier tube (MC-PMT) through a coherent optical fibre bundle. Each LSO crystal element measures 0.975 mm x 0.975 mm in cross section by 12.5 mm in length. A barium sulphate reflector material was used between LSO elements leading to a detector pitch of 1.15 mm in both axial and transverse directions. Fused optical fibre bundles were made from 90 mum diameter glass fibres with a numerical aperture of 0.56. Interstitial extramural absorber was added between the fibres to reduce optical cross talk. A charge-division readout circuit was implemented on printed circuit boards to decode the 196 crystals in each array from the outputs of the 64 anode signals of the MC-PMT. Electronics from Concorde Microsystems Inc. (Knoxville, TN) were used for signal amplification, digitization, event qualification, coincidence processing and data capture. Coincidence data were passed to a host PC that recorded events in list mode. Following acquisition, data were sorted into sinograms and reconstructed using Fourier rebinning and filtered backprojection algorithms. Basic evaluation of the system has been completed. The absolute sensitivity of the microPET II scanner was 2.26% at the centre of the field of view (CFOV) for an energy window of 250-750 keV and a timing window of 10 ns. The intrinsic spatial resolution of the detectors in the system averaged 1.21 mm full width at half maximum (FWHM) when measured with a Na-22 point source 0.5 mm in diameter. Reconstructed image resolution ranged from 0.83 mm FWHM at the CFOV to 1.47 mm FWHM in the radial direction, 1.17 mm FWHM in the tange

MicroPET II is a second-generation animal PET scanner designed for high-resolution imaging of small laboratory rodents. The system consists of 90 scintillation detector modules arranged in three contiguous axial rings with a ring diameter of 16.0 cm and an axial length of 4.9 cm. Each detector module consists of a 14 x 14 array of lutetium oxyorthosilicate (LSO) crystals coupled to a multi-channel photomultiplier tube (MC-PMT) through a coherent optical fibre bundle. Each LSO crystal element measures 0.975 mm x 0.975 mm in cross section by 12.5 mm in length. A barium sulphate reflector material was used between LSO elements leading to a detector pitch of 1.15 mm in both axial and transverse directions. Fused optical fibre bundles were made from 90 mum diameter glass fibres with a numerical aperture of 0.56. Interstitial extramural absorber was added between the fibres to reduce optical cross talk. A charge-division readout circuit was implemented on printed circuit boards to decode the 196 crystals in each array from the outputs of the 64 anode signals of the MC-PMT. Electronics from Concorde Microsystems Inc. (Knoxville, TN) were used for signal amplification, digitization, event qualification, coincidence processing and data capture. Coincidence data were passed to a host PC that recorded events in list mode. Following acquisition, data were sorted into sinograms and reconstructed using Fourier rebinning and filtered backprojection algorithms. Basic evaluation of the system has been completed. The absolute sensitivity of the microPET II scanner was 2.26% at the centre of the field of view (CFOV) for an energy window of 250-750 keV and a timing window of 10 ns. The intrinsic spatial resolution of the detectors in the system averaged 1.21 mm full width at half maximum (FWHM) when measured with a Na-22 point source 0.5 mm in diameter. Reconstructed image resolution ranged from 0.83 mm FWHM at the CFOV to 1.47 mm FWHM in the radial direction, 1.17 mm FWHM in the tange

Urbanism, Architecture and The Built Environment

This study reports the penetration properties of various Parylenes (i.e., C, N and HT) inside long microchannels. The work broadly covers the effects of the dimer type, loaded dimer mass, substrate temperature and channel size on the penetration length, i.e., the length that Parylene can be deposited into the microchannel from the inlet. Understanding the mechanism of Parylene penetration into microchannel helps to develop mass-producible inner surface protection design and process for microfluidic devices.

Urbanism, Architecture and The Built Environment

Contains fulltext : 136105.pdf (publisher's version ) (Open Access)

Urbanism, Architecture and The Built Environment

Contains fulltext : 136105.pdf (publisher's version ) (Open Access)

Contains fulltext : 136105.pdf (publisher's version ) (Open Access)

Urbanism, Architecture and The Built Environment

Over the past 20 years, tremendous advances have been made in the field of spinal cord injury research. Yet, consumed with individual pieces of the puzzle, we have failed as a community to grasp the magnitude of the sum of our findings. Our current knowledge should allow us to improve the lives of patients suffering from spinal cord injury. Advances in multiple areas have provided tools for pursuing effective combination of strategies for recovering stepping and standing after a severe spinal cord injury. Muscle physiology research has provided insight into how to maintain functional muscle properties after a spinal cord injury. Understanding the role of the spinal networks in processing sensory information that is important for the generation of motor functions has focused research on developing treatments that sharpen the sensitivity of the locomotor circuitry and that carefully manage the presentation of proprioceptive and cutaneous stimuli to favor recovery. Pharmacological facilitation or inhibition of neurotransmitter systems, spinal cord stimulation, and rehabilitative motor training, which all function by modulating the physiological state of the spinal circuitry, have emerged as promising approaches. Early technological developments, such as robotic training systems and high-density electrode arrays for stimulating the spinal cord, can significantly enhance the precision and minimize the invasiveness of treatment after an injury. Strategies that seek out the complementary effects of combination treatments and that efficiently integrate relevant technical advances in bioengineering represent an untapped potential and are likely to have an immediate impact. Herein, we review key findings in each of these areas of research and present a unified vision for moving forward. Much work remains, but we already have the capability, and more importantly, the responsibility, to help spinal cord injury patients now.

Over the past 20 years, tremendous advances have been made in the field of spinal cord injury research. Yet, consumed with individual pieces of the puzzle, we have failed as a community to grasp the magnitude of the sum of our findings. Our current knowledge should allow us to improve the lives of patients suffering from spinal cord injury. Advances in multiple areas have provided tools for pursuing effective combination of strategies for recovering stepping and standing after a severe spinal cord injury. Muscle physiology research has provided insight into how to maintain functional muscle properties after a spinal cord injury. Understanding the role of the spinal networks in processing sensory information that is important for the generation of motor functions has focused research on developing treatments that sharpen the sensitivity of the locomotor circuitry and that carefully manage the presentation of proprioceptive and cutaneous stimuli to favor recovery. Pharmacological facilitation or inhibition of neurotransmitter systems, spinal cord stimulation, and rehabilitative motor training, which all function by modulating the physiological state of the spinal circuitry, have emerged as promising approaches. Early technological developments, such as robotic training systems and high-density electrode arrays for stimulating the spinal cord, can significantly enhance the precision and minimize the invasiveness of treatment after an injury. Strategies that seek out the complementary effects of combination treatments and that efficiently integrate relevant technical advances in bioengineering represent an untapped potential and are likely to have an immediate impact. Herein, we review key findings in each of these areas of research and present a unified vision for moving forward. Much work remains, but we already have the capability, and more importantly, the responsibility, to help spinal cord injury patients now.

The next-generation implantable high-power prosthetic devices, such as retinal prostheses, will be powered by inductively coupled coils of high efficiency. However, the use of high-frequency power carriers almost always induces significant AC resistance due to skin and proximity effects, which limits the overall coupling efficiency. Inspired by the widely used round Litz wire, planar coils with planar Litz structures were investigated on the printed circuit board (PCB) and showed the reduced AC resistances in some specific frequency ranges. Herein, various planar Litz structures were introduced into previous MEMS foil coils, which have been proved to be superior over the conventional planar counterparts. The experimental results provided by the aforementioned prototypes showed a reduction of AC resistance up to 13.3% compared to a solid foil coil. A microfabrication process, which combines a single layer metal deposition and patterning with a post folding step, was developed to construct the planar Litz structure.

Over the past 20 years, tremendous advances have been made in the field of spinal cord injury research. Yet, consumed with individual pieces of the puzzle, we have failed as a community to grasp the magnitude of the sum of our findings. Our current knowledge should allow us to improve the lives of patients suffering from spinal cord injury. Advances in multiple areas have provided tools for pursuing effective combination of strategies for recovering stepping and standing after a severe spinal cord injury. Muscle physiology research has provided insight into how to maintain functional muscle properties after a spinal cord injury. Understanding the role of the spinal networks in processing sensory information that is important for the generation of motor functions has focused research on developing treatments that sharpen the sensitivity of the locomotor circuitry and that carefully manage the presentation of proprioceptive and cutaneous stimuli to favor recovery. Pharmacological facilitation or inhibition of neurotransmitter systems, spinal cord stimulation, and rehabilitative motor training, which all function by modulating the physiological state of the spinal circuitry, have emerged as promising approaches. Early technological developments, such as robotic training systems and high-density electrode arrays for stimulating the spinal cord, can significantly enhance the precision and minimize the invasiveness of treatment after an injury. Strategies that seek out the complementary effects of combination treatments and that efficiently integrate relevant technical advances in bioengineering represent an untapped potential and are likely to have an immediate impact. Herein, we review key findings in each of these areas of research and present a unified vision for moving forward. Much work remains, but we already have the capability, and more importantly, the responsibility, to help spinal cord injury patients now.

Urbanism, Architecture and The Built Environment

Urbanism, Architecture and The Built Environment

A portable leukocyte differential count is especially desirable for the emerging needs from bedside and NASA spaceflight healthcare. However, previous efforts to miniaturize the test using microfluidics have shown only a 3-part differential of leukocyte including lymphocyte, monocyte, and neutrophil, whereas the 5-part differential is still lacking. Here we report a complete 5-part differential leukocyte count, where lymphocyte, monocyte, neutrophil, eosinophil, and basophil are counted and classified on a microfluidic cytometer. This is done using a dye-staining assay with a two-color fluorescence detection scheme. The differential results are further validated by spiking whole blood samples with purified leukocyte cells.

This work presents a MEMS intraocular coil which is designed to be flexible, biocompatible and electrically efficient as the secondary power coil of inductive coupling links for retinal prostheses applications. A microfabricated structure of parylene-gold-parylene is combined with a folding technique to create a conducting strip with increased cross-section and length than is possible without folding, which is then wound to form a single-layer coil. Compared with the wire-wound coil and MEMS planar coil, our strip-fold-and-wound origami coil can better fulfill the size, mass, and flexibility requirements of an intraocular implant, and also reduce the proximity effect and achieve high quality factor at the targeted frequency. As an example, a 5-turn prototype coil of 10 mm outer diameter, 1 mm thickness and 10 mg weight in saline, has an inductance of 480 nH and reaches a maximum Q factor of 12.5 at 30 MHz. A further increase of Q factor can be achieved by increasing the equivalent cross-sectional area by depositing thicker metal.

The lack of simple but reliable microvalves is still a serious problem for many lab-on-a-chip applications. This work studied the use of blood coagulation, the transformation of liquid blood into solid coagulum, as a possible valving mechanism for microfluidic control and demonstrated a one-time open-to-close valve. This is done by creating a solidified blood coagulum, which clogs a normally-open fluidic channel as a closed valve. Local thermal coagulation is demonstrated using a focused laser for blood heating. This clogging valve can withstand a back pressure of 22 psig or higher and its simple structure is well-suited for disposable devices.

Urbanism, Architecture and The Built Environment

Urbanism, Architecture and The Built Environment

This paper mainly uses the method of Urban Morphology to study the transformation process of urban form of Xiguan historical district in Guangzhou, P.R.China. The paper tries to analyze the transformation process through studying the background of politics, economy, society, culture and natural condition of Xiguan area. It further discusses the structural feature and transformation rule, as well as analyzes the hidden dynamics. Considering time as the main factor, the paper mainly focuses on two aspects—form elements and dynamics, trying to study the relation between each other. The paper aims at concluding the overall transformation feature and rule of Xiguan area and bringing up some perspectives on the protection and continuity of traditional urban fabric and culture in the process of urban renewal. The body of this paper is organized through tracing the transformation of urban form in different periods of time. First, to study the foundation of form transformation through demonstrating the construction background of Xiguan area before Qing Dynasty; Second, to discuss separately the form feature of Qing Dynasty, the period of the Republic of China and the period after the foundation of New China. The form feature is mainly analyzed in several aspects as the street feature, property plot, building type, land use and street space; Finally, to summarize the transformation rule on the basis of overall analysis of transformation feature of Xiguan area, and then to conclude the main dynamics of form transformation, as well as to discuss the practical significance for the protection of Xiguan historical district and urban renewal., Urbanism, Architecture and The Built Environment

This paper mainly uses the method of Urban Morphology to study the transformation process of urban form of Xiguan historical district in Guangzhou, P.R.China. The paper tries to analyze the transformation process through studying the background of politics, economy, society, culture and natural condition of Xiguan area. It further discusses the structural feature and transformation rule, as well as analyzes the hidden dynamics. Considering time as the main factor, the paper mainly focuses on two aspects—form elements and dynamics, trying to study the relation between each other. The paper aims at concluding the overall transformation feature and rule of Xiguan area and bringing up some perspectives on the protection and continuity of traditional urban fabric and culture in the process of urban renewal. The body of this paper is organized through tracing the transformation of urban form in different periods of time. First, to study the foundation of form transformation through demonstrating the construction background of Xiguan area before Qing Dynasty; Second, to discuss separately the form feature of Qing Dynasty, the period of the Republic of China and the period after the foundation of New China. The form feature is mainly analyzed in several aspects as the street feature, property plot, building type, land use and street space; Finally, to summarize the transformation rule on the basis of overall analysis of transformation feature of Xiguan area, and then to conclude the main dynamics of form transformation, as well as to discuss the practical significance for the protection of Xiguan historical district and urban renewal., Urbanism, Architecture and The Built Environment

This work demonstrated leukocyte count and two-part leukocyte differential from the whole blood based on a portable microflow cytometer system. Leukocytes are selectively stained with a fluorescent dye, Acridine Orange (AO). The blood sample is then pumped through a disposable microfluidic device for fluorescence sensing. Under blue LED excitation (460nm), the green fluorescence from DNA and the red fluorescence from RNA are detected simultaneously with two photomultiplier tubes (PMT). Leukocytes are counted and differentiated into two parts, lymphocyte versus non-lymphocyte, based on their fluorescence signatures. The results, including leukocyte absolute count and lymphocyte ratio, matched well with the commercial hemacytometer counts (maximal error 9.0%, correlation coefficient ~0.8). We also tested the system for the first time under a zero-gravity (zero-G) environment that facilitated its application in space missions.

We present the development of a three-dimensional (3-D), on-glass combinatorial cell culture array chip featured with integrated three-input, eight-output combinatorial mixers and cell culture chambers. The device is designed to simultaneously screen for the effects of multiple compounds and concentrations on cultured cells. Experimentally, we first developed a precise way to characterize the combined compound concentration profile at each chamber with a fluorescence method. We then successfully demonstrated the functionality of the cell assay by culturing neuron cells on this device and screening the ability of three chemicals to attenuate cell death caused by cytotoxic hydrogen peroxide. Based on the same technology, the number of inputs and outputs of the combinatorial mixer can be scaled-up to construct labon-chip devices for performing high-throughput cell-based assay and highly parallel and combinatorial chemical or biochemical reactions with reduced labors, reagents, and time.

This work reports the design, fabrication, testing and modeling of electrolysis-based fully encapsulated parylene balloon actuators. The proposed actuators have the advantage of high force at low power and low voltage. The main issues are low actuation speed and limited number of actuation cycles due to loss of water by permeation through the balloon membrane. In our case, the actuators are targeted to move neuroprobes after implantation, where slow movement is acceptable but low power consumption is of demand.

Over the past 20 years, tremendous advances have been made in the field of spinal cord injury research. Yet, consumed with individual pieces of the puzzle, we have failed as a community to grasp the magnitude of the sum of our findings. Our current knowledge should allow us to improve the lives of patients suffering from spinal cord injury. Advances in multiple areas have provided tools for pursuing effective combination of strategies for recovering stepping and standing after a severe spinal cord injury. Muscle physiology research has provided insight into how to maintain functional muscle properties after a spinal cord injury. Understanding the role of the spinal networks in processing sensory information that is important for the generation of motor functions has focused research on developing treatments that sharpen the sensitivity of the locomotor circuitry and that carefully manage the presentation of proprioceptive and cutaneous stimuli to favor recovery. Pharmacological facilitation or inhibition of neurotransmitter systems, spinal cord stimulation, and rehabilitative motor training, which all function by modulating the physiological state of the spinal circuitry, have emerged as promising approaches. Early technological developments, such as robotic training systems and high-density electrode arrays for stimulating the spinal cord, can significantly enhance the precision and minimize the invasiveness of treatment after an injury. Strategies that seek out the complementary effects of combination treatments and that efficiently integrate relevant technical advances in bioengineering represent an untapped potential and are likely to have an immediate impact. Herein, we review key findings in each of these areas of research and present a unified vision for moving forward. Much work remains, but we already have the capability, and more importantly, the responsibility, to help spinal cord injury patients now.

In this paper, we study the corrosion behavior of parylene-metal-parylene thin films using accelerated-lifetime soak tests. The samples under test are thin film resistors with a 200 nm layer of Au sandwiched by parylene-C on both sides, fabricated with parylene-metal skin technology. The samples are tested in hot saline both passively and actively, and different failure modes are observed using optical and electron-beam metrologies. Bubbles and delamination are first seen in the samples after 2 days of soaking under passive conditions, and followed by metal corrosion. While under active conditions, either bubbles or parylene breakdowns are observed depending on the thickness of parylene packaging. These results contribute to a better understanding of the failure mechanisms of parylene packaging in body fluids.

In this paper, we study the corrosion behavior of parylene-metal-parylene thin films using accelerated-lifetime soak tests. The samples under test are thin film resistors with a 200 nm layer of Au sandwiched by parylene-C on both sides, fabricated with parylene-metal skin technology. The samples are tested in hot saline both passively and actively, and different failure modes are observed using optical and electron-beam metrologies. Bubbles and delamination are first seen in the samples after 2 days of soaking under passive conditions, and followed by metal corrosion. While under active conditions, either bubbles or parylene breakdowns are observed depending on the thickness of parylene packaging. These results contribute to a better understanding of the failure mechanisms of parylene packaging in body fluids.

Recent advances in the field of neural prosthetics have demonstrated the thought control of a computer cursor. This capability relies primarily on electrode array surgically implanted into the brain as an acquisition source of neural activity. Various technologies have been developed for signal extraction; however most suffer from either fragile electrode shanks and bulky cables or inefficient use of surgical site areas. Here we present a design and initial testing results from high electrode density, silicon based arrays system with an integrated parylene cable. The greatly reduced flexible rigidity of the parylene cable is believed to relief possible mechanical damages due to relative motion between a brain and its skull.

Novel flexible parylene-based high-density electrode arrays have been developed for functional electrical stimulation in retinal and spinal cord applications. These electrode arrays are microfabricated according to single-metal-layer and, most recently, dual-metal-layer processes. A new heat-molding process has been implemented to conform electrode arrays to approximate the curvature of canine retinas, and chronic implantation studies have been undertaken to study the mechanical effects of parylene-based prostheses on the retina, with excellent results to date. Electrode arrays have also been implanted and tested on the spinal cords of murine models, with the ultimate goal of facilitation of locomotion after spinal cord injury; these arrays provide a higher density and better spatial control of stimulation and recording than is typically possible using traditional fine-wire electrodes. Spinal cord stimulation typically elicited three muscle responses, an early (direct), a middle (monosynaptic), and a late (polysynaptic) response, classified based on latency after stimulation. Stimulation at different rostrocaudal levels of the cord yielded markedly different muscle responses, highlighting the need for such high-density arrays.

This work presents a new electrolysis-based microelectromechanical systems (MEMS) diaphragm actuator. Electrolysis is a technique for converting electrical energy to pneumatic energy. Theoretically electrolysis can achieve a strain of 136 000% and is capable of generating a pressure above 200 MPa. Electrolysis actuators require modest electrical power and produce minimal heat. Due to the large volume expansion obtained via electrolysis, small actuators can create a large force. Up to 100 µm of movement was achieved by a 3 mm diaphragm. The actuator operates at room temperature and has a latching and reversing capability.

This work presents a new electrolysis-based microelectromechanical systems (MEMS) diaphragm actuator. Electrolysis is a technique for converting electrical energy to pneumatic energy. Theoretically electrolysis can achieve a strain of 136 000% and is capable of generating a pressure above 200 MPa. Electrolysis actuators require modest electrical power and produce minimal heat. Due to the large volume expansion obtained via electrolysis, small actuators can create a large force. Up to 100 µm of movement was achieved by a 3 mm diaphragm. The actuator operates at room temperature and has a latching and reversing capability.