Miniaturization of electronics modules is always required for various medical applications including wearable technology, such as hearing aids, and implantable devices. Many types of high-density packaging technologies, such as package-on-package, bare-die stack, flex folded package and Through Si Via (TSV) technologies, have been proposed and used to fulfill the request. Among them, embedded die technology is one of the promising technologies to realize miniaturization and high-density packaging. We have developed WABE™ (wafer and board level device embedded) technology for embedding dies into multilayer flexible printed circuit (FPC) boards. The WABE package is comprised of thin dies (85 μm thickness), multi-layer polyimide, adhesive films and conductive paste. The dies are sandwiched by polyimide films with Cu circuits (FPCs). The conductive paste provides electrical connections between the layers as well as the layer and embedded die. First, each FPC layer is fabricated individually, and via holes are filled with conductive paste, and the dies are mounted on certain layers. Then, all layers undergo a one-step co-lamination process, and they are pressed to cure the adhesive material and conductive paste at the same time. This WABE technology has enabled multiple dies to be embedded by the one-step lamination process. Even if multiple dies are embedded, the footprint of a package can be reduced drastically by embedding multiple dies vertically in stacks. This paper describes the details of the results of fabricating a test vehicle with six embedded dies (three-dies in two stacks side-by-side). The fabricated test vehicle had 14 copper layers with less than 0.9 mm thickness. This paper also reports the results of various reliability testing on the package. These results were obtained by electrical measurements of daisy chain patterns formed between some of the layers. The fabricated test vehicle showed high reliability based on the results of a moisture and heat test and heat-shock test. These results show that the WABE technology to embed multiple dies vertically in polyimide film is one of the most promising packaging technologies to significantly miniaturize electronic circuits such as medical electronics.

The number of young people getting total hip arthroplasty surgery is on the rise and studies have shown that the average number of perfect health years after such surgery is being reduced to about 9 years; this is because of complications which can lead to the failure of such implants. Consequently, such failures cause the implant not to last as long as required. The uncertainty in design parameters, loading, and even the manufacturing process of femoral stems, makes it important to consider uncertainty quantification and probabilistic modeling approaches instead of the traditional deterministic approach when designing femoral stems. This paper proposes a probabilistic analysis method which considers uncertainties in the design parameters of femoral implants to determine its effect on the implant stiffness. Accordingly, this method can be used to improve the design reliability of femoral stems. A simplified finite element model of a femoral stem was considered and analyzed both deterministically and probabilistically using Monte Carlo simulation. The results showed that uncertainties in design parameters can significantly affect the resulting stiffness of the stem. This paper proposes an approach that can be considered a potential solution for improving, in general, the reliability of hip implants and the predicted stiffness values for the femoral stems so as to better mitigate the stress shielding phenomenon.

Cerebrospinal fluid shunts for the treatment of hydrocephalus fail at a rate of 40% within the first year. The importance of this problem is supported by one institution’s analysis of neurosurgical 30-day readmissions with CSF shunt failure only second to brain tumor readmissions. Hospital shunt related costs have been estimated at $1.4 to $2 billion annually. The majority of these costs are attributable to shunt failures based on the number of revisions out of the total numbers of annual shunt procedures. The technical innovation of this project is a low cost, low risk and easy to implement CSF shunt design change compatible with current protocols. The proposed product is an innovative distal catheter to minimize the need for revision surgery due to obstruction (also referred to as occlusion). This is accomplished with a dual lumen catheter (current distal catheters are single lumen) consisting of a primary lumen and a secondary lumen providing redundant functionality in the event ofprimary lumen occlusion thereby eliminating the need for surgical shunt revision. 40% of shunts fail within the year after implant and distal catheter obstruction accounts for up to 24% of failures. Though less prevalent than proximal catheter occlusion, incidence of distal catheter occlusion is significant and improved reliability would reduce costs and improve patient outcomes by lowering the number of revisions.

Device companies commonly install memory chips in a disposable or semi-reusable attachment within a product assembly [1]. Attachment examples include single-use medical diagnostic sensors, reusable monitoring probes, disposable catheters and plug in tools having limited cutting, connection or sterilizing cycles. The memory chip provides information about the attachment to a hosting device that controls or operates the attachment. This stored information may include the attachment’s number of connections or uses, calibration coefficients [2] and the manufacturer or patient identification and date. This attachment data can then be used to enforce product requirements regarding reliability, accuracy, safety and brand [3,4]. For example, the host device can alarm the user, shutdown, or prevent attachment operation when the memory data is outside the product’s validated or tested limits.

Anterior cruciate ligaments (ACL) injuries account for a significant proportion of all sports-related injuries. Despite successful completion of a rehabilitation program, about 35% of ACL patients experience re-injury after return to sport, and studies have identified persistent quadriceps strength deficits as a potential cause [1–3]. Deficits in quadriceps strength can be monitored throughout rehabilitation using muscle strength testing. The most common test protocol involves isometric testing of quadriceps strength whereby the knee is extended against a static resistance. In this method, the clinician uses their strength to resist the patient’s motion and subsequently assigns a qualitative value of strength. The highly subjective nature of this test has motivated clinicians to use devices that can more accurately assess quadriceps strength.

While the use of pulsatile- and continuous-flow ventricular assist devices (VADs) has become widely accepted as an acceptable treatment for end-stage heart failure in adults over the last three decades, the technology development for pediatric-specific patients is lagging behind that of adult devices. Only one pulsatile-flow VAD has been approved for use in pediatric patients in the U.S., just five years ago [1]. One continuous-flow device was approved specific to this population under Humanitarian Device Exemption (HDE), but is not in clinical use today [2]. As continuous-flow rotary blood pumps (RBPs) have become commonplace for mechanical circulatory support (MCS) in adults due to smaller size and greater reliability, significant resources have gone into the development of RBPs for pediatric use [3]. Further, RBPs designed for adult MCS have been used off-label in pediatric patients [4]. Development of an implantable device specific to a pediatric population includes challenges of anatomic placement and fixation. We have developed a RBP for adult MCS specific to right heart failure using computational fluid dynamics (CFD) and flow visualization [5]. The miniaturized device includes a rotating impeller and a vaned-diffuser in a 7 mm axial hydraulic diameter. As seen in Figure 1, the hydrodynamic characteristics suitable for a right-VAD (RVAD) may also be suitable for pediatric patients. Currently, the only approved device is placed extracorporeal due to size constraints in the intended population [1]. This report shows results of computational simulations for anatomic fit and fluid flow studies of our device geometry in pediatric patients.

Spasticity is a common consequence of the upper motor neuron syndrome and usually associated with brain lesion, stroke, cerebral palsy, spinal cord injury, and etc. On the other hand, rigidity is a neuromuscular disorder often found in Parkinson’s disease patients. Both of spasticity and rigidity are characterized by abnormal hypertonic muscle behaviors that will cause discomfort and hinder daily activities. Worldwide, the estimated affected population of spasticity is around 12 million [1], and rigidity affects more than 10 million people [2]. Clinical evaluation of spasticity or rigidity involves personal assessment using qualitative scales, such as the Modified Ashworth Scale (MAS) or Modified Tardieu Scale (MTS) for spasticity and Unified Parkinson’s Disease Rating Scale (UPDRS) for rigidity. However, this evaluation method heavily relies on the rater’s personal experience/interpretation and usually results in poor consistency and low reliability. The goal of this design was to develop a quantitative measurement device that can be used to assist clinical evaluation of spasticity or rigidity. This portable device, the Position, Velocity, and Resistance Meter (PVRM), can be strapped around a patient’s limb to measure angular position, angular velocity and muscle resistance of a given joint while the patient’s limb is passively stretched by the clinician. Acquiring this quantitative data from patients will not only allow clinicians to make more reliable assessments but also help researchers gain additional insights into the quantification of spasticity and rigidity.

A Stellite 25 17mm tube valve based upon the Björk-Shiley Monostrut (BSM) valve design was developed for use in the Penn State Pediatric Ventricular Assist Device (PVAD) pump [1]. The hook of the valve was designed to hold a Delrin occluding disc in place while allowing the disc to tilt open 70 degrees from the closed position. Unlike common design constraints which remain in the elastic region, the hook experiences plastic deformation twice during the assembly process, making the material choice of Stellite 25 imperative. Stellite 25 is a cobalt-chromium-tungsten-nickel alloy (Co-20Cr-15W-10Ni) belonging to the material family of superalloys which are commonly used for wear-resistant applications exposed to heat, abrasion, and galling [2, 3]. Along with its excellent in vivo corrosion resistance [4], Stellite 25 exhibits high strength and ductility which permit the hook to be plastically deformed during disc installation while remaining below the strain to failure [3, 4]. Together these qualities make Stellite 25 an ideal material choice for the 17mm tube valve application. Predicting the resultant stresses and strains is critical for determining the safety and structural reliability of the Stellite 25 17mm tube valve for the PVAD after assembly. After performing finite element analysis (FEA), the simulation results were validated by deflection experiments and metallurgical investigations.

Three case studies are presented in which computational-based methodologies have been used to assess structural reliability in the aerospace industry. The studies involve hot section turbine disks of a helicopter engine, fan blades of a commercial airline engine and bearings in an auxiliary power unit. In all cases, the results of the computational models were used to support the certification process for design and application changes. The statistical variation in design and usage parameters including geometry, materials, speed, temperature and other environmental factors are considered. The response surface approach was used to construct a durability performance function. This performance function is used with the first order reliability method (FORM) to determine the probability of failure and the sensitivity of the failure to the design and usage parameters. A hybrid combination of perturbation analysis and Monte Carlo simulation is used to incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system durability to the design and usage parameters.

The majority of medical devices are monitoring devices. Therefore, data communication and analysis are playing a crucial rule in predicting the effectiveness and reliability of a device. Device related data, patient related data and device-patient related data stored in Data Bases (DBs) are great sources for enhancing either new designs or improving already existing ones. Analyzing such data can provide researchers and device development teams with a complete justification and patterns of interest about a device’s performance, life and reliability. Data can be formulated into stochastic models based their statistical characteristics to consider the variability in data and the uncertainty about processes and procedures during early stages of the design process. This strengthens the device’s ability to function under a broader range of operating conditions. The work herein aims at targeting unwanted variations in device performance during the device development process. It employs a novel technique for variation risk management of device performance based historical process data modeling and visualization. The introduced technique is a proactive systematic procedure comprises a tool set that is being placed in the larger framework of the risk management procedure and fully utilizing data from the DBs to predict and address the risk of variations at the early stages of the design process rather than at the end of each major stage.

The continuing need for enhanced efficacy, safety, and/or functionality in in vivo therapeutics provides immense opportunity for microelectromechanical systems (MEMS). However, continuing reliance upon materials adopted from the semiconductor industry may ultimately limit the scope of what can be achieved. Many such materials suffer from poor mechanical reliability due to low fracture toughness, which results in extreme sensitivity to stress concentration and predisposition to catastrophic failure by fracture. Although mitigation via robust design and packaging is sometimes possible, this invariably increases complexity and cost. Moreover, in many emerging applications, these avenues are not available, due to design constraint and/or performance restriction, thus underscoring need for development of viable alternatives. Herein, we present an overview of high-aspect-ratio titanium micromachining techniques we have developed to address this need. We then follow with a brief summary of recent results from several applications currently under development. In each, Ti micromachining provides a means for leveraging a host of advantageous properties that yield potential for enhanced safety, reliability, and/or performance. As such, Ti micromachining shows considerable promise for extending the utility of MEMS for in vivo therapeutics.

Field Programmable Gate Arrays (FPGAs) have dramatically changed the design of medical devices in the past decade. FPGAs offer the flexibility of writing software on a standard microprocessor and the reliability and performance of dedicated hardware. In the design of medical devices that previously required the rigorous design of custom circuits or ASIC design, FPGAs are providing a good alternative at a much lower cost for low to mid-volume medical device design. In this session, we will explore how FPGAs relate to medical device technology including real-time processing of data, high performance image processing, precise control, and code reuse from prototype to deployed device. We will explore how this technology was applied to two devices that improve the success of high-risk surgeries. In the first, FPGA technology is used to monitor blood glucose levels in patients during open-heart surgery. The second example is a device that simulates electrical signals from the human nervous system to train neurophysiologists for events that may happen during surgery. We will explore the impact FPGAs have on design cycles, briefly explore the design process, and compare different programming methodologies including C, VHDL, and LabVIEW. Finally, we will discuss the impact of FPGAs with respect to the 510k process.

The capacity to quantify gait in autonomous scenarios may substantially alleviate the rampant strain on limited, scarce, and highly specialized medical resources. A strategy for enabling application autonomy, for which the subject may reside at a remote distant from the clinical resources, has been demonstrated through the research, development, test, and evaluation of wireless accelerometers for gait analysis. An approach for maximizing accuracy and reliability has been demonstrated through the selection of a predetermined anatomical mounting position relative to the human anatomy. Wireless accelerometer systems have presented quantified disparity for the gait of hemiparetic subjects. For the quantification of hemiparetic gait, the selected mounting positions were the lateral epicondyle of the femur and also the lateral malleolus [1].

The implementation of a wireless accelerometer application for the quantification of gait may enable an autonomous strategy for the quantification of gait. A wireless accelerometer application may potentially enable the remote, autonomous, and quantified evaluation of gait beyond the confines of a clinical facility. The accuracy and reliability for the application of accelerometers for gait evaluation has been established through the selection of specific mounting positions based on the anatomy of the subject. Wireless accelerometer systems have been successfully demonstrated for establishing a quantified gait disparity for hemiparetic subjects. For example, the quantification of hemiparetic gait has been conducted using the lateral epicondyle of the femur as a mounting position [1].

Compliant mechanisms are flexible devices that transform an input force to a displacement through elastic deformation. Advantages of using compliant mechanisms are that they are monolithic devices that contain flexible members that can undergo large deflection, have fewer joints, have increased reliability, increased precision and have fewer components compared to rigid-body mechanisms.

Environmental conditions can have major influence on the lifetimes and reliability of active implantable medical devices (e.g., neurostimulators, cochlear implants, internal cardioverter defibrillators). These environmental conditions can range from those encountered by the device in processing and production to transportation and storage to actual operation. Although one might argue that the environmental conditions found in the first two situations are harsher than those of the third, failures that result from those situations are screened before implantation. If we assume that the active medical device is in perfect operational form at the time it is implanted, it will still experience a host of environmental conditions that can affect reliability. In fact, the ultimate goal of these medical devices is to restore the patient, wherever they may reside, to normal activities. A list of some environmental conditions that may be experienced by a device implanted in a representative patient is found in Table 1.

Studies of reliability in current practice indicate that reliability based on conventional methods requires a nonlinear transformation to a set of normal distributions, which effectively changes the shape of limit state function. In this paper, the general formulation of safety for aluminum elements and the associated methods of analysis are reviewed. Direct simulation is used to find the probability of failure. It is concluded that direct simulations of safety of aluminum elements of Pr (probability of failure) by failure counting is a good method to achieve acceptable safety factors.

Miniaturization of devices is driving replacement of electronic components with surface mount technology (SMT) equivalent parts, including any embedded sensing devices. In many cases the size of the sensor is restricted by the minimum size of the package rather than by the die. Other solutions to preserve real-estate involve manual mounting of the die onto substrates that have gone through an SMT assembly process. The +/-2g accelerometer presented here is, to our knowledge, the first wafer-level packaged device with solderable terminals that allows the silicon die to be mounted directly onto a substrate in a standard SMT process and without the need for stressisolating interposers. With its small footprint and ceiling requirements (2.1 × 2.9 × 0.8 mm 3 ), and robustness and high performance it is the smallest commercially-available packaged accelerometer suitable for medical applications where these characteristics are critical. The device features terminals that are electrically and mechanically separated but robust enough to withstand large shear forces that may occur during use and board assembly. The device was solder mounted on a variety of substrates without affecting its performance. Most significantly, both device and solder joints were able to withstand extended thermal cycling over a wide temperature range (-55 to 125°C). In this paper, we present the device design, the performance and the long-term reliability test results of this novel and high-performance device on a variety of substrates and solder materials.

The success rates of dental implant treatments in posterior mandible and maxilla could be compromised due to the increased masticatory forces and poor bone quality. In addition, the length of the implant is limited by maxillary sinus and mandibular canal in these regions. Wide-diameter short (WDS) implants provide a good alternative to increase the stability and the reliability of the implants in such conditions. The objective of this study is to evaluate the biomechanical properties of a wide implant by performing finite element analyses (FEA). Comparison of the strain distribution induced in the bone by a WDS implant and by a narrow-diameter long (NDL) implant, in clinical scenarios exhibiting different amounts of crestal bone, and under varying insertion depths demonstrated that WDS implant can be used safely and should perform as well as its NDL counterpart.