Engineering Design Controls for Efficient Medical Device Development

Early stage medical device development teams investigate many alternatives before selecting a final design proposal. The team must be able to retrace and reproduce successful designs and understand factors that underpin decisions that came before. This is especially important in a university setting due to the natural turnover on the team that is inherent in a successful research group. Effective design control provides this support to the design team.

Experimental Study and CFD Analysis of the Volumatic® Spacer

The aim of the present study was to evaluate the performance of Ventilan® coupled to the Volumatic® spacer. An experimental study was conducted using the four stage Multistage Liquid Impinger (MSLI). This enabled the observation that half of the pharmacological dose is retained within the body of the spacer. Therefore, the air flow inside the spacer was studied, along the respiratory cycle, using Fluent™. Several recirculation regions were observed inside the spacer that may influence the aerosol flow and also the deposition of the drug.

System Development and Testing of a Liquid Needle-Free Injector

A simple approach is presented to determine several critical parameters of a liquid needle-free injector. A jet injector system was developed based on the approach, and its jet characteristics were tested.

Articular Contact Estimation by Surface Reconstruction Based on True Geometry

The intra-articular contact characteristics of the diarthrodial joints have been measured by using Fuji pressure sensitive films and a Tekscan sensor system. Direct measurement can only provide resultant contact information. Indirect contact estimation methods, such as mathematical modeling or a stereophotogramametric method can be used to estimate contact kinematics on each articulating surface. However, indirect estimation methods are often based on simplified geometry due to limited accuracy or simplification, resulting in erroneous contact estimation. The objective of this study was to quantify the intra-articular contact area and shape of the glenohumeral joint determined by surface reconstruction. The results showed that the contact estimation method using surface reconstruction was in good agreement with the results of Tekscan measurement (accuracy ≤ 5.3% and repeatability ≤ 11.2%). The contact estimation method may provide a valuable avenue for understanding contact kinematics in human diarthrodial joints.

Smart Endoscopic Tool for the Measurement of Force and Softness of Grasped Object in Minimally Invasive Surgery

One of the shortcomings of the current endoscopic graspers is the lack of tactile sensing. We are reporting the results of the first stage of a research project to rectify the tactile sensing in endoscopic tools. This paper introduces a smart endoscopic grasper equipped with sensors for measuring the applied force and the angle of the grasper tip. It is shown that using this method, the softness of the grasped object can be estimated. The next phase of this research would be devising an appropriate method to feedback the measured date.

Micropallet Technology for Investigating Tumor Cellular Profiles and Analysis of Rare Cell Subsets

Rationally designed, individualized therapeutic strategies have long been a desired objective for breast cancer patients and clinicians as an estimated 178,480 new cases of invasive breast cancer will be diagnosed among women in the United States this year and over 40,000 women are expected to die from the disease. [1] The increasing appreciation of breast tumor cellular heterogeneity raises fundamental questions as to the relative contributions of cellular subsets to the biologic behavior of an individual patient’s tumor. [2] As such, it has become increasingly clear that in many cases, an individualized strategy for the treatment of breast cancer would be of great benefit, and that the ability to isolate relevant cellular subsets from the main tumor population is one of the critical limits to accomplishing this goal.

Production of Monodisperse Micron-Size Droplets Using Silicon-Based MHz Ultrasonic Nozzles for Biomedical Applications

This paper reports production of 4.5 μm-diameter monodisperse water droplets using silicon-based one MHz ultrasonic nozzles of a novel design. The novel design of multiple Fourier horns in resonance facilitates pure capillary wave mechanism atomization. The measured drop diameters are in very good agreement with those predicted by the capillary wave atomization mechanism. Due to the resonance effect, the power and voltage requirements for atomization were as low as 15 mW and 6.5 V at atomization rate as high as 300 μl/min. The droplet diameter was reduced to 4.1 μm when the surface tension of the liquid was reduced from 70 dyne/cm (water) to 50 dyne/cm (0.25% Triton X-100 surfactant solution). Such small diameter drops with GSD (geometrical standard deviation) as small as 1.1 was achieved in ultrasonic atomization for the first time. Note that the fraction of all particles smaller than 5.8 μm in diameter represents the inhaleable fine particle fraction and GSD of 1.3 or smaller is commonly accepted as the standard for monodispersity. Therefore, the MEMS-based MHz ultrasonic nozzle should have very significant impacts on targeted delivery of reproducible doses of medicine to the respiratory system.

Endo-Distraction: A New Technique of Distraction Osteogenesis in High Atrophic Mandibles — Results of 18 Patients

The aim of this study is to evaluate the surgical and prosthetic results of edentulous patients with highly atrophic mandibles using the Endo-Distraction technique.

Putting a Charge in Healing: Electrical Stimulators Show Great Promise, Especially for Spinal Fusions

Spinal fusion is the latest application of electrical stimulation as a fracture healing. This exciting new application has been proven over 30 years of use, and the market is now poised for rapid growth. Patent activity shows an increased interest in this technology, and both start-up companies and orthopedic giants can thus benefit from introducing new products in this field.

The PediaFlow Pediatric Ventricular Assist Device

This paper describes a design process for a new pediatric ventricular assist device (VAD), the PediaFlow. The VAD is a magnetically levitated turbodynamic pump design for chronic support of infants and small children. The design entailed the consideration of multiple pump topologies, from which an axial mixed-flow configuration was chosen for further optimization via computation fluid dynamics. The magnetic design includes permanent-magnet (PM) passive bearings for radial support of the rotor, an actively controlled thrust actuator for axial support, and a brushless DC motor for rotation. These components are closely coupled both geometrically and magnetically, and were therefore optimized in parallel, using electromagnetic, rotordynamic and fluid models. Multiple design objectives were considered including efficiency, size, and margin between critical speed to operating speed. The former depends upon the radial and yaw stiffnesses of the PM bearings. Analytical expressions for the stiffnesses were derived and verified through FEA. A toroidally-wound motor was designed for high efficiency and minimal additional negative radial stiffness. The design process relies heavily on optimization at the component-level and system-level. The results of this preliminary design optimization yielded a pump design with an overall stability margin of 15 percent, based on a pressure rise of 100 mmHg at 0.5 lpm running at 16,000 RPM.