bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Design for Modularity of Laparoscopic Tools
Authors: Miller David J. , Nelson Carl A.
Published: July 2008

Background: A functional analysis of current laparoscopic surgical technology prompted a redesign to provide multiple functionalities within a single tool. Novel mechanisms were needed to actuate and deploy functional tips to the surgical site from their storage locations. Methods: Functional Decomposition was used to determine problems with the current minimally invasive surgery (MIS) paradigm. Axiomatic Design was used to ensure an efficient design. Quality Function Deployment was used to mathematically determine important design criteria. Results: The actuation mechanism transfers squeezing motion from the hand through a gear train to the distal end of the tool where a pin-slot mechanism actuates the tool tip. An ergonomic slider mechanism translates linear thumb motion into rotation of the tool’s shaft through a gear train. A binary ratcheting mechanism is used to lock or unlock the tool with identical motions. Methods for indexing functional tips within the tool and interfacing the tips with a lead screw were designed for a modular tool. Rotary indexing of the tool cartridge is done using a Geneva-type mechanism and cam∕follower to provide positive locking once the tip is in place. Proper alignment of the tool tip with the actuation∕shuttling screw is accomplished using a screw∕wedge assembly. Conclusions: Benefits include multiple functionalities in a single tool, ergonomic benefits of an increased I∕O force scaling, decreased out-of-plane motion required to rotate the tool’s shaft and decreased cognitive effort required to lock and unlock the tool’s jaws.
Development of an Automated Laser Debridement System for Cutaneous Injuries
Authors: Rastegar J. , Soroff H. , Murray R. T.
Published: July 2008

The initial step in the repair of a thermal or chemical burn is wound debridement, the removal of the dead skin covering the burn. Afterwards, the exposed wound is covered with a viable biological dressing, the scabs re-form and the process must be repeated until the wound is fully healed. Of the various methods of wound debridement, surgical excision is the most popular. The process uses stainless steel cutting blades mounted on different types of handles which have built-in adjustments for controlling the depth of the excision. The main problems with this treatment method are excessive bleeding and lack of high-precision control of the cutting depth. Recent advances have been made in healing treatments for thermal and chemical burns using a variety of techniques to debride damaged tissue, including the use of medical lasers, such as CO2 and Er:YAG lasers. Excision using laser beams has been shown to be associated with significantly reduced morbidity, since the amount of blood lost during debridement is significantly reduced because the depth of treatment is more precise and the process has a cauterization cycle built-in. One drawback to the available laser systems is that they all require the surgeon to move a hand piece over the damaged area. This process requires great operator skill and is time consuming for an injury with a large surface area. Small hand held scanners attached to the end of articulated arms have mitigated this drawback to some extent, but the scanned areas are relatively small and the surgeon still needs to move the scanner head over larger injuries. This project describes the development of an automated, 3D vision guided laser debridement system with a large maximum working area for efficiently treating injuries with large areas or a multitude of smaller injuries distributed over a large area. This system is designed to be fail-safe, and performs precise debridement automatically and quickly with minimal surgeon involvement.
Radiographic Marking of Patient’s Gravity Line on X-Ray Images
Authors: Wu Chunhui , Mehbod Amir A. , Transfeldt Ensor
Published: July 2008

Objective: To develop a clinically feasible apparatus for measuring and marking patient’s gravity line position on spinal x-ray images. Background: Spinal balance of patients with deformity or instability is an important clinical parameter for patient diagnosis, surgery planning and treatment outcome evaluation. Traditional assessment of spinal balance is performed on full spine x-ray images using C7 plumb line relative to central sacral line in the coronal plane or posterior superior corner of S1 in the sagittal plane. Researchers have developed measurement techniques using a force plate synchronized with x-ray equipment and offline x-ray image processing. The complexity of these techniques limits their clinical applications. In this study, we present a new system to mark gravity line directly on an x-ray image. Methods: The system consists of a force plate, a signal conditioner and processor, a motion controller and a motor assembly that moves a radio-opaque marker. The processor calculates the location of gravity line and marker position, and transmits motion commands to the motion controller, which drives a motor assembly and moves the marker to appropriate positions. The acquired x-ray image has a mark indicating the instantaneous gravity line position. Evaluation: A prototype was installed in the radiology department. More than 200 patients were instructed to stand on the force plate. Exposure was performed as in routine x-ray imaging. The system does not affect routine x-ray workflow and provides valuable information for spine surgeons.
Computer Simulation of Female Urinary Incontinence
Authors: Zhang Yingchun , Timm Gerald W. , Erdman Arthur G.
Published: July 2008

Objectives: The purpose of this study is to establish pressure, distension and other parameters involved that produce tissue injury during vigorous physical activities in women, so that superior methods and devices for diagnosing and treating urinary incontinence (UI) can be created. Background: A higher prevalence of daily UI in a female athlete population was found compared to that of a randomly selected and age matched sample population, but the mechanism of UI is not clearly understood. Methods: Mechanical tissue properties of affected organ structures were determined by using specimens from cadavers. A realistic geometric model of the female pelvis was developed from patients’ specific CT images. The finite element model was built by combining the mechanical tissue properties and the geometry of organs involved, and the finite element analysis (FEA) was then performed using ABAQUS 6.7 to simulate the biomechanical response of the female pelvis during physical activities. Results: Tissue specimens from 11 cadavers were tested which included specimens of the bladder, uterus, pelvic muscle, vagina and urethra. A finite element model was built with approximately 500,000 tetrahedral elements. The force level and resulting organ displacements in the female pelvis during physical activities were investigated successfully by using the FEA method. Discussion: The knowledge of force level and organ displacements during physical activities helps to understand the mechanisms of UI occurring during physical activities.
A Wireless, Passive Strain Sensor: Application to In Vivo Monitoring of Compressive Forces at Knee Implants
Authors: Tan Ee Lim , Ong Keat Ghee
Published: July 2008

This study describes the design of a new wireless and passive sensor for in vivo strain monitoring at knee replacements. In a total knee arthroplasty, the proximal end of the tibia and the two femoral condyles are replaced with artificial components, and a high-density polyethylene insert is placed between the two components. The wear and tear of the polyethylene insert is considered a threat to the long-term survival of many knee implants. We have designed a wireless, implantable strain sensor to study the stresses experienced by the polyethylene insert. The sensor, which is embedded within the insert, is comprised of a magnetically soft material (sensing element) and a magnetically hard material (biasing element) separated by a deformable∕flexible layer. Under AC magnetic field, the sensing element generates a secondary, higher-order mode magnetic flux that can be measured with a magnetic inductive coil. Additional stresses to the sensor deform the flexible layer, altering the higher-order magnetic flux and thus allowing remote measurement of compressive forces. The advantages of this sensor are, its wireless and passive nature, small size, and cost effectiveness. The remote query nature of this sensor allows long-term implantation and real-time monitoring of human body. Experimental results have shown that the sensor responded linearly with applied stress and demonstrated good repeatability and stability. We believe that the outcome of this project will greatly improve public health by leading to a better implant design and providing a convenient way to detect wear and tear of knee implants.
PMMA Implants Increase Femoral Strength
Authors: Dragomir-Daescu Dan , Bolander Mark E. , Bennet Kevin E. , Bronk James T. , McEligot Sean
Published: July 2008

The number of osteoporotic hip fractures is projected to increase two to three fold in the next 30years. This will lead to increased mortality and nursing home placement with significant costs to our society. Although in clinical trials drug and hormone therapies have shown an important decrease in fracture risk there is a significant role of surgical implantation treatments to further reduce the risk in specific subpopulations. Strength testing was completed on four pairs of osteoporotic, two pairs of osteopenic, and two pairs of normal cadaver femurs. The fracturing was recorded with a video camera at 4000 frames per second. The specially designed test fixture was instrumented with three load cells to measure the femoral forces. Force and moment data were recorded simultaneously and correlated with the frames. The fracture force at the greater trochanter was used to characterize the strength of implanted∕nonimplanted osteoporotic femurs. All femurs began fracturing within about 60ms at a test speed of 100mm∕s. During the first 20ms, the relationship between force and displacement was nonlinear, but linear thereafter until the fracture occurs. The fracture events resolved completely within 10–20ms. The average strength increase of the implanted femurs was 79% compared to the nonimplanted controls. The simultaneous acquisition of fracture images and load data is a powerful tool to understand and characterize numerically the femoral fracture. This methodology allows the researcher to define the best metrics to compare competing reinforcement materials, implant designs and surgical procedures.
Chronic VNS for the Treatment of Morbid Obesity
Authors: Pardo Jose V.
Published: July 2008

Eight patients with treatment-resistant depression (TRD) underwent adjunctive chronic VNS for periods up to 14months. Although the patients denied dieting or change in activity level, there was a slow and highly significant loss of weight accompanied by decreased metabolism in the ventromedial prefrontal cortex, a cortical area involved in interoception with dense connections to the hypothalamus. The loss of weight was proportional to the initial weight. Weight loss was not related to change in depression scores. Neuromodulation through VNS may offer a novel approach to weight regulation.
Charged Modification of Hydrogel for Nerve Regeneration
Authors: Dadsetan Mahrokh , Knight Andrew M. , Vallejo Catalina , Lu Lichun , Windebank Anthony J. , Yaszemski Michael J.
Published: July 2008

Natural and synthetic hydrogels have attracted much attention for nerve regeneration. Previous studies have shown that electrical charge has significant effect on stimulation of neurite outgrowth. In this work, incorporation of a positively charged monomer into the photocrosslinkable oligo(polyethylene glycol) fumarate (OPF) hydrogel has been investigated. We have evaluated the effect of localized positive charge on neurite outgrowth in culture with an objective that positively charged hydrogels ultimately can be used for stimulating in vivo nerve regeneration. The effect of charged modification has been also studied on mechanical properties and swelling ratio of these hydrogels. Our data indicated that with increasing charge density hydrogels swelling ratio increased in water, however it remained constant in PBS. We also demonstrated that compressive modulus and tensile strength of the hydrogels improved with incorporation of electrical charge into the hydrogels. Biodegradation of modified hydrogels was investigated in a series of biomimetic solutions. OPF hydrogels appeared to be more susceptible to oxidative degradation as opposed to the hydrolytic degradation in enzymes and acidic solution, and the degradation rate was correlated to the PEG molecular weight and charge density of the hydrogels. To investigate the effect of charge modification on nerve cell attachment and differentiation, dissociated dorsal root ganglion (DRG) cells were plated onto the modified and unmodified hydrogels surfaces. DRG cells attached and extended their neurites more readily on the surface of positively charged hydrogels as opposed to the unmodified hydrogels.
Design and Fabrication of a Micropump With Mixing Function for LOC
Authors: Kang Ho-jin , Choi Bum-kyoo
Published: July 2008

A micropump, which includes a mixing function, has been fabricated. For the application to LOC (Lab On a chip), the micropump utilized PBS (Phosphate Buffered Saline) solution as the working medium. The solution is commonly used in biochemistry and cell culturing. The portable system and low energy consumption are important to realize the LOC device. In spite of a low voltage of 4V, the flow rate of the micropump was 0.02466ml∕min. The new micropump shows more enhanced performance than existing micropumps. The micropump uses Lorentz force actuation. The Lorentz force acting onto the ionic current in the PBS solution generates the fluid flow in the micropump. For the accurate prediction on flow direction, a computer simulation has been made using commercial CFD code. The results of simulation showing circulation direction were verified by experiment. The fluid circulation from each electrode combined and acted as the mixer in the micropump. The micropump was fabricated 20.2mm in length, 1mm in width and 400 μm in electrode length. To measure accurately, a high speed digital camera was used.
Comparison of Geometries for Diffusion-Based Extraction of Dimethyl Sulphoxide From a Cell Suspension
Authors: Glass Katie Fleming , Mata Clara , Longmire Ellen K. , Hubel Allison
Published: July 2008

Microfluidics can be used in a variety of medical applications. In this study, a microfluidic device is being developed to remove cryoprotective agents from cells post thaw (1–150ml). Hematopoietic stem cells are typically cryopreserved with Dimethyl sulphoxide (DMSO), which is toxic upon infusion. Conventional methods of removing DMSO results in cells losses of 25–30%. The overall objective of this study is to characterize the influence of flow geometry on extraction of DMSO from a cell stream. For all the flow geometries analyzed, flow rate fraction, Peclet Number, and channel geometry had the greatest influence on extraction of DMSO from the cell stream. The range of flow rate fractions that can achieve the desired removal ranges between 0.10 and 0.30. Similarly, the range of Peclet numbers is 250–2500. Distinct differences in channel length could be observed between the different flow configurations studied. The flow rates and channel geometries studied suggest that clinical volumes of cell suspensions (1–100ml) can be processed using a multi-stage microfluidic device in short periods of time (<1hr).
Combining Shape Memory Alloys and Microfluidic Chips on Printed Circuit boards
Authors: Vyawahare Saurabh , Sitaula Suresh , Martin Sujitha , Adalian Dvin , Scherer Axel
Published: July 2008

Integrated multi-layer fluidic chips, with hundreds of elastomeric valves, are useful in immunoassays, protein crystallization, cell culture and several other applications. Although the devices are micro-scale, because valves are actuated pneumatically, each chip requires a relatively large pneumatic control system for operation. Fulfilling the great promise of microfluidics, for instance building throwaway, portable, massively parallel, point-of-care diagnostic systems is unlikely until there is a solution for actuating micro-valves electrically. We introduce a combination of materials—shape memory alloys (SMAs) and elastomersto solve this problem. SMAs offer among the highest work per unit volume of any actuator, and elastomers have the ability to absorb the energy and return the SMA to its original configuration, while providing electric and thermal insulation. Using this marriage of materials, with PDMS (elastomer) and Ni/Ti wires (SMA), we built electrically activated micro-fluidic valves, peristaltic pumps and multiplexers. The first generation valve design needs 50 to 250 mA current in the on state, with power requirements of about 0.5 W. It can hold back >1 atmosphere of pressure and run for thousands of cycles, actuating at sub-second speeds. The dead volume is <1 nano-liter. Crucially, these devices are assembled on printed circuit boards, like conventional electronic components. Thus, the technology used in assembling electronics is applicable to assembling fluidic chips, and both electronics and fluidics can be integrated on one platform for biomedical applications.
An Innovative Rapid Thermal Cycling Device for Polymerase Chain Reaction
Authors: Mahjoob Shadi , Vafai Kambiz
Published: July 2008

Polymerase chain reaction (PCR) is the most commonly used molecular biology technique to amplify nucleic acid (DNA and RNA) in vitro. This technique is highly temperature sensitive and thermal management has an important role in PCR operation in reaching the required temperature set points at each step of the process (denaturing, annealing and elongation). In this work, an innovative microfluidic PCR thermal cycling device is designed to increase the heating∕cooling thermal cycling speed while maintaining a uniform temperature distribution throughout the substrate containing the aqueous nucleic acid sample. The device design is incorporating the jet impingement and micro-channel thermal management technologies utilizing a properly arranged configuration filled with a porous medium. Porous Inserts are attractive choices in heat transfer augmentation. They provide a very large surface area for a given volume which is a key parameter in heat transfer processes. Various effective parameters that are relevant in optimizing this flexible thermal cycler are investigated such as thermal cycler configuration, thickness of inlet and exit fluid channels, fluid flow rate and velocity, the porous matrix material and properties, and utilization of thermal grease. An optimized case is established based on the effects of the cited parameters on the temperature ramp, temperature distribution and the required power for circulating the fluid in the thermal cycler. The results indicate that the heating∕cooling temperature ramp (temperature change per heating∕cooling cycling time) of the proposed device is considerably higher (150.82◻C∕s) than those in literature. In addition, the proposed PCR offers a very uniform temperature in the substrate while utilizing a low power.
A Wireless, Passive Sensor for Monitoring the Pressure of an Abdominal Aortic Aneurysm Sac
Authors: Pereles Brandon D. , Ong Keat Ghee
Published: July 2008

Abdominal aortic aneurysms (AAA), which claim the lives of 15,000 Americans annually, occur when the aortic walls are weakened to the point of bulging or rupture. Besides aorta replacements, AAA is commonly treated with an endovascular aortic repair procedure that reinforces the aorta by inserting a stent via a leg artery. While this procedure is effective, failure of the stent may increase the pressure of the AAA sac and cause the aorta wall to rupture. Therefore, monitoring of the pressure in the AAA sac is critical for post surgery assessment. We present the design and fabrication of a wireless passive pressure sensor for measuring the pressure of an AAA sac after stent placement. The sensor is made of a hermetically sealed chamber with two opposite membranes. A magnetically soft film is attached on one of the membranes, and a permanent magnetic film is placed on the other. As the membranes deflect due to changes in sac pressure, the separation distance between the magnetic elements changes. This in turn varies the magnetic harmonic fields of the magnetically soft film, allowing remote pressure monitoring with the use of a magnetic coil. Compared to Endosure, a wireless passive sensor developed by CardioMems that operates by remotely measuring the resonant frequency change of a capacitive-inductive circuit, the proposed device is thinner and can be miniaturized to a long and thin strip. Its signal is also not reduced by the electrically dense body since it is interrogated through magnetic fields.
Design of Novel Catheter Insertion Device
Authors: Bassett Erik K. , Slocum Alexander
Published: July 2008

Poor positioning of needles and catheters may result in repeated attempts at correct placement, injury to adjacent structures or infusions into inappropriate spaces. Existing catheter insertion methods do not uniformly provide feedback of the tip location, nor prevent the needle from going beyond the target space. The purpose of this research was to develop a design tool to be used to create a new catheter insertion device. This device would advance a needle in firm tissue but automatically release it upon entrance into the desired space. The system studied consisted of a flexible filament (OD ∼0.9mm) in compression passing through a tube (ID 1.22mm) with both straight and curved sections. A mathematical model based on oil drilling methods was developed to predict the compressive force dissipated in the filament for any given tube geometry. A correction factor on one of the two terms in the model was necessary to achieve best results, but proved to be accurate for all 100+ tests completed. With it, this model accounted for the following parameters: Angular displacement of tube bends, radial clearance, coefficient of friction, lengths, tube and filament radii, number of bends, moment of inertia, and modulus of elasticity. Implementation of this model should allow for a more safe and effective catheter insertion device.
Guidewire Reproducibilty and Modeling
Authors: Hoffmann Kenneth R. , Schafer Sebastian , Noel Peter B. , Singh Vikas , Xu Jinhui
Published: July 2008

The number of minimally invasive vascular interventions is increasing, and the device most frequently used is a guidewire, along which devices are delivered to the intervention site. Procedural failure can occur due to improper guidewire and∕or device selection. To facilitate guidewire and device guidance, we investigated the reproducibility of guidewire paths in vessel phantoms. Several trained users repeatedly passed guidewires of different flexibility through the phantoms under pulsatile flow conditions. Afterwards, the 3D paths were reconstructed and compared. In addition, the 3D paths were calculated using graph representation techniques. Points in the vessel lumen in planes perpendicular to the vessel centerline were generated. All points in adjacent planes were joined generating a vector set in a graph representation in which the edge weights were functions of the angle between contiguous vectors. The optimal path through this weighted directed graph was then determined using a Dijkstra’s (shortest path) algorithm. The guidewire paths appear reproducible across users but not across materials. The average RMS difference of repeated placements was 0.17±0.02mm (plastic-coated guidewire), 0.73±0.55mm (steel guidewire) and 1.15±0.65mm (steel vs plastic-coated). For the guidewire modeling, the average RMS distance between the actual and simulated guidewire path was 0.7mm; computation time was 3s. For a given guidewire, these results indicate that the guidewire path is relatively reproducible in shape and position. The ability to predict the guidewire path inside vessels may facilitate calculation of vessel-branch access and force estimation.
A Totally Implantable Hearing Device for Restoration of Hearing
Authors: Gan Rong Z. , Dai Chenkai , Nakmali Don , Wood Mark W.
Published: July 2008

Middle ear implantable hearing devices as an emerging and effective technology can offer advantages to the individuals with mild to moderately severe sensorineural hearing loss. Several devices with piezoelectric or electromagnetic transducers have been developed. A totally implantable hearing system (TIHS) consisting of a subcutaneous microphone, sound processor, and electromagnetic transducer has been investigated. The design of the TIHS has incorporated the bioengineering approaches based on a 3D finite element (FE) computational model of the human ear and the FE analysis of electromagnetic coupling of the transducer. In this paper, we report the technologies developed for the TIHS and experimental measurements in bench setup and human temporal bones with the TIHS prototype. The tests conducted on the device to characterize its performance across the auditory frequency range include: 1) mass loading effect on residual hearing with the passive implant, 2) effectiveness of the electromagnetic coupling between implanted coil and magnet, and 3) function characterization of whole unit in response to acoustic input across the skin. The results indicate that the TIHS prototype tested in human cadaver ears or temporal bones shows satisfactory performance of the system. The data obtained from those preliminary studies will be used for future clinical trails of the TIHS.
Multi-Compartment Cooling∕Warming Garment for Human Thermal Dynamic Research and Medical Applications
Authors: Koscheyev Victor S. , Leon Gloria R. , Lee Joo-Young , Warpeha Joe M. , Saltzman Daniel A.
Published: July 2008

Human thermoregulatory research is fraught with multifaceted physiological issues. A notable quandary is the fact that the human body has several different types of tissues, each with unique heat transfer/conductive properties. The primary goal of our research is to determine how to effectively and appropriately regulate human thermal physiology in the context of medical, occupational, and sporting fields. Of paramount importance is quantifying heat extraction/insertion from various body regions under different heat surplus/deficit situations imposed by environmental conditions and/or metabolic fluctuations, and understanding the associated mechanisms and their relationships. Our laboratory has conducted research involving the simulation of contradictory thermal regimes on the body surface to observe the dynamic process of simultaneous heat insertion and extraction. To achieve this, we have designed a tubing cooling/warming garment through which water circulates and controller (patent #7,089,995) that can provide the desired thermal stimuli in uniform/non-uniform and symmetrical/non-symmetrical patterns. We believe this methodology of divided surfaces for the application of concurrent cooling/warming regimes affords the greatest opportunity to quantify the maximum zonal capabilities for heat transfer. This paradigm allows for the regulation of heat flow in dynamic non-uniform conditions and is particularly suited for the comfort/support of a range of clinical populations (e.g., surgical, multiple sclerosis, burns/trauma, hyper/hypothermia). It is also applicable for the design of protective clothing for personnel in occupational settings (e.g., military, firefighting, space flyers), and for sporting apparel (i.e., a cooling garment/hood/blanket). Our laboratory has used the physiologically designed cooling/warming garment to evaluate individual thermoregulatory profiles elicited by conditions representative of extreme terrestrial and space thermal environments.
Development of A Medical Device for Quantitative Physical Therapies
Authors: Zeng Hansong , Haq Furqan , Best Thomas , Agarwal Sudha , Butterfield Tim , Zhao Yi
Published: July 2008

Physical therapies using mechanical loadings are widely used for improving and recovering the physical activities of human tissues. It is generally accepted that such therapies promote health and well-being by many mechanisms, including fastening muscle blood flow, parasympathetic activity, releasing relaxation hormones and inhibiting muscle tension, neuromuscular excitability and stress hormones. Nonetheless, most of current research in this area is based on statistics and thus qualitative, preventing the in-depth study of the effectiveness of these therapies. It is partially due to the lack of appropriate tools for quantitative loading and in situ tissue evaluation. To address this, we developed a medical device that resembles the mechanical motions and loadings that occur in massage therapies by applying combinations of compressive and shear loadings to the subject tissues. This device consists of a loading wheel, a force sensor, a pneumatic actuator, a control system and a data acquisition system. In this work, mechanical forces were applied to the lower limbs of rabbits with controllable magnitudes, frequencies and durations. The changes of mechanical properties of the subjects, including the compliance and the viscosity, were in situ measured as a function of the loading dose, and correlated to the results from biomolecular assay. This device can quickly identify the optimal sets of loading parameters which lead to high effectiveness, and thus provide guidance to practitioners to design their therapies. It is also expected to shed light on the fundamental study of biomechanical forces in regulation of the physiologic conditions of cells and tissues.
Non-Intrusive ECG Measurement on Vehicle Steering Wheel and Driver Seat
Authors: Hu Shan , Bowlds Ryan , Yu Xun
Published: July 2008

Driver drowsiness is one of the major causes of deadly traffic accidents. Continuous monitoring of drivers’ drowsiness thus is of great importance for preventing drowsiness-caused accidents. Previous psychophysiological studies have shown that heart rate variability (HRV) has established differences between waking and sleep stages. This offers a way to detect driver’s drowsiness by analyzing HRV, which is typically measured and analyzed from electrocardiogram (ECG) signal. Although ECG measurement techniques are well developed, most of them involve electrode contacts on chest or head. Wiring and discomfort problems inherent in those techniques prevent implementing them on cars. This research develops two non-intrusive real-time ECG measurement methods for drivers. In the first method, each half of the steering wheel is wrapped with conductive fabric as electrode and is isolated to each other. In the second one, two pieces of conductive fabric with the same dimension are placed on the driver seat’s backrest. Signals from conductive fabric electrodes are filtered by differential low pass, band pass and notch filters to amplify ECG signals and suppress noise. Noise whose frequency overlaps with the frequency range of ECG signal cannot be eliminated by these filters. To address this challenge, an adaptive filter is employed for baseline noise cancellation. Experimental tests show that both ECG measurement methods can provide clear ECG signals for further HRV analysis, although signals from the steering wheel are of better quality. Test results also demonstrate that the adaptive filter can effectively cancel baseline noise.
Construction of a Magnetic Biosensor for Pathogen Detection
Authors: Li Yuanpeng , Castro Marlene , Im Hyungsoon , Yao Xiaofeng , Oh Sang-Hyun , Hu Wei-Shou , Wang Jian-Ping
Published: July 2008

Current methods for pathogen detection require days before a result is available, while biosensors offer the advantage of quick, on the spot results. In this project we present the proof of concept of a biosensor that uses giant magnetoresistance (GMR) sensors and a microfluidic system. The bioprobe consists of a 30 bp oligonucleotide, 5′ functionalized with a thiol group (T-DNA30) immobilized on a gold surface. Hybridization was tested with a 5′-biotinylated oligonucleotide complementary to T-DNA30 to which Streptavidin-R-Phycoerythrin was attached later. The difference in fluorescence between the target sample and control samples was observed using a scanning laser confocal fluorescence microscope. The GMR device consists of an Ir0.8Mn0.2∕Co0.9Fe0.1∕Cu∕Co0.9Fe0.1∕Ni0.82Fe0.12 multilayer structure. Magnetic nanoparticles were deposited directly on the surface of the GMR sensors. An external magnetic field was employed to polarize the nanoparticles, which can then be detected by comparing the resistance change loops of the GMR sensors before and after their deposition. A transparent elastomer, polydimethylsiloxane (PDMS), was used for the microfluidic system. The system comprises two microfluidic channels separated by a 200μm PDMS wall. The channel width is 200μm and its height 100μm. The PDMS channel was permanently bonded to the SiO2 surface of the GMR sensor. The integrated biosensor will immobilize thiolated DNA on the gold surface below which the GMR device is located. For hybridization, biotinylated DNA will be used. Finally, magnetic nanoparticles, coated with streptavidin will be attached to the hybridized DNA and detected by the GMR device.
Progress on Clinical Trials and Product Development of a Simple, Inexpensive Feedback Device for Patients Requiring Partial Weight Bearing
Authors: Walczyk Daniel , Ordway Nathaniel , Mann Kenneth , Ziomek William
Published: July 2008

A weight bearing indicator (WBI) has been developed and is undergoing clinical trials and commercialization. The most recent version of the device includes load range indication ability. The WBI is installed in a patient’s medical appliance (e.g. cam walker boot, surgical shoe) and allows patients recovering from lower extremity injuries to self monitor their rehabilitation. It is a simple and inexpensive mechanical device that utilizes the reversible buckling phenomena of a snap dome to provide a tactile ‘click’ and an audible ‘snap’ when a specified ground load on the bottom of a patient’s foot, which has been prescribed by an orthopedist or podiatrist as the partial weight bearing (PWB) upper limit, has been met or exceeded. A clinical study involving 20 subjects showed that PWB compliance improved when comparing the WBI device to standard of care approaches such as verbal instruction and the weight scale method. Specifically, PWB compliance improved from 58% and 45% body weight (BW) for verbal instruction and weight scale method, respectively, to 33% BW for the WBI device. In addition, PWB compliance using the WBI device was not dependent on subject weight like the standard of care approaches. Sometimes patients are instructed not only to avoid exceeding an upper load limit, but also to maintain their limb load above a lower limit as well. A newer version of the WBI has been developed that provides two distinct clicks to a patient corresponding to an upper and lower load limits.
An Instrument to Predict Fall Risk—Project StepWiz
Authors: Hanson Mats , Meymi David , Nilsson Daniel , Oddsson Lars , Rockstr Robin
Published: July 2008

Falls are the most common cause of injuries and the primary etiology for accidental deaths in the elderly population. The ability to quickly take a step is of paramount importance in maintaining balance. Previous research has shown a significant correlation between the time it takes to execute a step and the risk of experiencing a future fall. Consequently, a method that can quickly and accurately measure step behavior may be used to identify individuals with an increased risk of falling. The current project has built a prototype device that can be used in a clinical setting to easily and efficiently measure parameters of step execution. The step is performed under either single task (motor task only) or dual task conditions (motor task while performing an attention demanding cognitive task). Data can be stored in a relational data base and a clinical report that reflects fall risk can be printed. The current project is part of the Swedish PIEp initiative (Product Innovation Engineering Program), a federally and industry supported program that promotes innovation and technology commercialization in engineering education through development of innovation knowledge, experience and education including exchange of students and personnel between industry and academia on a national and international level.
Self-Stimulatory Behavior Detection Using Wearable Sensors for Children With Autistic Spectrum Disorder
Authors: Min C.-H. , Tewfik A. , Kelly A.
Published: July 2008

An affordable, user-friendly and reliable infrastructure that supportsevidence based tools for health assessment of children withAutistic Spectrum Disorder (ASD) has been developed. This systemcan detect the behaviors of children at various stages of autismand enables the therapist and parents to monitor, assist diagnosisand therapies of autistic children. The system incorporates 2different sensor platforms which are wearable and static. Thewearable system consists of a 3-axis accelerometer, small microprocessor and a Bluetooth module to transmit data to the basestation. This wearable device integrates these 3 modules to a customizedPrinted Circuit Board (PCB) which can be worn as a cuff or could be sewed intothe sleeves of a child's shirt. The static sensor is composed of an audio sensorand a webcam which detects the sound/speech and captures video data of thesubject within the room. Using this sensor system, we are able to achieve thenecessary information for assessment and therapy in autism research.Based on the data collected and our preliminary analysis, we wereable to detect and recognize several self-stimulatory behaviors of achild with autism. The device allows for a continuous monitoringof the activities and self-stimulatory behaviors. It benefits both therapistsand parents by helping them to better understand the behaviors of an autisticchild and it will also enable early diagnosis of ASD.
Methodologies for Performing Non-Invasive Stimulated Muscle Force Assessment in Critically Ill Patients
Authors: Ginz H. F. , Iaizzo P. A. , Urwyler A.
Published: July 2008

Objective: To optimize the assessment of muscle weakness in critically ill patients in the intensive care unit (ICU) by development non-invasive, reproducible assessment devices and application protocols. Methods: For over 5years we evaluated weakness in ICU patients by employing a prototype non-invasive muscle force assessment system. We determined peak torques, peak rates of torque development and decay of the ankle dorsiflexors after supramaximal peroneal nerve stimulation. We continue to test modifications of our devices (i.e. different stabilizing boots, extendable leg support systems, electrodes) so to optimize this important clinical assessment. Results: Measurements were performed in over 30 severely ill adult patients. During their illnesses, one observed dramatic reductions in stimulated torques, and during the recovery period, values increased to 70–80% of initial values. In those patients who died, the values continuously decreased until death. Throughout these investigations, several technical problems arose: i) the current device could not be used on patients in a prone position; ii) the mechanism used to adjust and lock ankle slipped; iii) edema made nerve stimulation difficult (altered skin conductance and difficult to maintain electrode position); iv) device was bulky for positioning (e.g., weight), and∕or v) stimulus parameters could not be readily adjusted. Discussion: Stimulated muscle force assessment can be used to study ICU patients’ forces. Nevertheless, next generation force assessment systems should be smaller, lighter, more portable, with a simple angle adjustment means, easier to use with a computer-controlled stimulator and include EMG recordings.
Imaging Depth-Resolved Tissue Birefringence With a Single Detector
Authors: Al-Kaisi Muhammad K. , Akkin Taner
Published: July 2008

We report a novel frequency multiplexed optical coherence tomography (FM-OCT) system that is capable of measuring depth-resolved tissue birefringence from a single record of a single detector. The FM-OCT system utilizes polarization-maintaining-fiber based components. The orthogonal channels of the polarization-maintaining-fiber and the cross-terms are frequency multiplexed. After recording the interference signal, a set of digital band-pass filters extract the polarization information. A rapid scanning optical delay line in the reference arm compensates for dispersion and allows a real-time display of tissue birefringence. The axial resolution provided by a superluminescent diode working at 855nm with 28nm bandwidth is 12μm. The accuracy and sensitivity measurements suggest that the FM-OCT system is suitable for depth-resolved birefringence characterization of biological tissue.
Application of Computational Biomechanics in Bioprosthetic Heart Valve Design
Authors: Sun Wei , DeHerrera Milton
Published: July 2008

For more than 40years, the replacement of diseased natural heart valves with prosthetic devices has dramatically improved the quality and length of the lives of millions of patients. Bioprosthetic heart valves (BHV), which are composed of biologically derived tissues, have good hemodynamic performance and do not require the anticoagulation therapy necessary when mechanical heart valves are implanted. However, these bioprostheses continue to fail due to structural failure resulting from poor tissue durability and faulty design. AHA∕ACC guideline recommends use of BHV for patients 65years or older, primarily due to its current 10–15years of limited durability. Clearly, an in-depth understanding of the biomechanical behavior of BHV is essential to improving BHV design to reduce rates of failure and increase its durability. Objective: develop a robust computational model to simulate BHV deformations and optimize its design. Methods: Experimentally driven, nonlinear, anisotropic material models are used for modeling the mechanical properties of valve leaflets; A novel method of constructing parametric finite element models is used to rapidly generate 3D free-from geometries of BHV for valve design optimization; Valve design parameters, such as peak stresses and effective orifice area (EOA) are evaluated. Results: multiple applications of the approach demonstrate the feasibility of utilizing computational biomechanics in BHV design. The computational approach provides us with an efficient new platform to develop and optimize the next generation heart valve design such as transcatheter valve and valve repair device design.
A Study on the Compliance of a Right Coronary Artery and Its Impact on Wall Shear Stress
Authors: Zeng Dehong , Boutsianis Evangelos , Ammann Marc , Boomsma Kevin , Wildermuth Simon , Poulikakos Dimos
Published: July 2008

A computational model incorporating physiological motion and uniform transient wall deformation of a branchless right coronary artery (RCA) was developed to assess the influence of artery compliance on wall shear stress (WSS). Arterial geometry and deformation were derived from modern medical imaging techniques, whereas the blood flow was solved numerically employing a moving-grid approach using a well-validated in-house finite element code. The simulation results indicate that artery compliance affects the WSS in the RCA heterogeneously, with the distal region mostly experiencing these effects. Under physiological inflow conditions, coronary compliance contributed to phase changes in the WSS time history, without affecting the temporal gradient of the local WSS nor the bounds of the WSS magnitude. Compliance does not cause considerable changes to the topology of WSS vector patterns nor to the localization of WSS minima along the RCA. We conclude that compliance is not an important factor affecting local hemodynamics in the proximal region of the RCA while the influence of compliance in the distal region needs to be evaluated in conjunction with the outflow to the myocardium through the major branches of the RCA.
Modeling the Effects of Variable Intake Valve Timing on Diesel HCCI Combustion at Varying Load, Speed, and Boost Pressures
Authors: Genzale C. L. , Kong S.-C. , Reitz R. D.
Published: July 2008

Homogeneous charge compression ignition (HCCI) operated engines have the potential to provide the efficiency of a typical diesel engine, with very low NOx and particulate matter emissions. However, one of the main challenges with this type of operation in diesel engines is that it can be difficult to control the combustion phasing, especially at high loads. In diesel HCCI engines, the premixed fuel-air charge tends to ignite well before top dead center, especially as load is increased, and a method of delaying the ignition is necessary. The development of variable valve timing (VVT) technology may offer an important advantage in the ability to control diesel HCCI combustion. VVT technology can allow for late intake valve closure (IVC) times, effectively changing the compression ratio of the engine. This can decrease compression temperatures and delay ignition, thus allowing the possibility to employ HCCI operation at higher loads. Furthermore, fully flexible valve trains may offer the potential for dynamic combustion phasing control over a wide range of operating conditions. A multidimensional computational fluid dynamics model is used to evaluate combustion event phasing as both IVC times and operating conditions are varied. The use of detailed chemical kinetics, based on a reduced n-heptane mechanism, provides ignition and combustion predictions and includes low-temperature chemistry. The use of IVC delay is demonstrated to offer effective control of diesel HCCI combustion phasing over varying loads, engine speeds, and boost pressures. Additionally, as fueling levels are increased, charge mixture properties are observed to have a significant effect on combustion phasing. While increased fueling rates are generally seen to advance combustion phasing, the reduction of specific heat ratio in higher equivalence ratio mixtures can also cause noticeably slower temperature rise rates, affecting ignition timing and combustion phasing. Variable intake valve timing may offer a promising and flexible control mechanism for the phasing of diesel HCCI combustion. Over a large range of boost pressures, loads, and engine speeds, the use of delayed IVC is shown to sufficiently delay combustion in order to obtain optimal combustion phasing and increased work output, thus pointing towards the possibility of expanding the current HCCI operating range into higher load points.