The prevalence and devastating nature of cardiovascular diseases has led to many advancements in the therapies used to treat the millions of patients that suffer as a result of these conditions. As coronary artery disease (CAD) is the most common of these cardiovascular conditions, it is a major focus of research among the medical industry. Although lifestyle changes and drug therapies can treat early CAD, more advanced cases often require more definitive interventions. In conjunction with angioplasty, stenting of an occluded vessel has shown significant success in preventing restenosis. However, as with nearly every therapeutic process in the medical field, several complications have arisen in stented patients that pose a need for further improvement of the devices. As a result, the stent industry is constantly striving towards improving the characteristics and outcome of their product and with these efforts comes the need for extensive testing and research. Continuous improvement and innovation in the field of tissue engineering has brought about the possibility of creating laboratory grown tissue engineered vascular grafts (TEVGs) for the purpose of replacing and/or bypassing damaged or occluded regions of the vasculature. By employing the techniques used to produce TEVGs, a blood vessel mimic (BVM) bioreactor system has been developed with the intent of using the resulting construct as a model for testing the cellular response of a human blood vessel to an intravascular device such as a stent. This would allow gathering of more significant data in the early stages of device development and may reduce the overall costs and time required to refine a design. Although the BVM system has previously been used to cultivate viable constructs that were subsequently used to observe the response to a deployed stent, the flow conditions within the original design are not representative of the physiologic conditions in a native vessel. This aspect of the original system presented a need for development in order to be considered by researchers as an accurate in vitro representation of the target vessels in which the stents are used. One of the primary concerns of this environment is creating and maintaining physiologic flow conditions that will represent those present in native vessels in order to facilitate cells sodded on the construct to grow as they would under native conditions. The two key aspects of flow are pulsatility and wall shear stress. Studies in this thesis were carried out to determine the best and most feasible methods for implementing appropriate levels of pulsation and wall shear stress in the previously established BVM bioreactor system with the intention of maintaining the original system’s simplicity and high throughput potential. Pulsatile flow was created by elevating backpressure in the BVM chamber while using a different pump head and pump tubing. Wall shear stress was adjusted by altering the viscosity of the perfusate and flow rate through the system. Both pulsatile flow and shear stress were established without any major changes to the overall configuration of the system. Pulsatile pressures of ~80 mmHg and wall shear stress forces of ~6.4 dyn/cm2 were established with minimal alteration to the original system. Pulsatility was created by using a 3-roller peristaltic pump head in place of the originally specified 8-roller head to create pulses that were then regulated with backpressure created by restricting down stream flow. Increasing the viscosity and corresponding flow rate allowed for instigation and control of wall shear stress at the inner wall of the BVM graft. Although the resulting protocols presented here require refinement for ultimately successful implementation, they are important underpinnings that will facilitate the eventual development of an ideal BVM system that is highly suitable for use as a high-throughput intravascular device testing model.

California Polytechnic State University, San Luis Obispo is a university that encourages students to approach learning hands-on. As such, there is cutting-edge technology being developed by students in all departments on campus. Being that the university possesses an outstanding biomedical engineering department, there are groundbreaking medical devices that students are creating at Cal Poly SLO. These are devices that can better the lives of individuals suffering from ailments or fulfill needs in the medical industry. Subsequently, it is vital that these devices make it out of campus laboratories and into the hands of consumers. In order to move a product from ideation to the market, numerous steps must be completed and often times, especially with the challenges of commercializing medical devices, these efforts can result in failed product launches. As such, there is demand for a commercialization process to be created at Cal Poly SLO that will aid student created medical devices in reaching the market. This paper documents the progress made thus far on such a process at Cal Poly SLO.

With more young adults requiring total hip arthroplasties the need for bone saving implants becomes more important. The Zimmer Fitmore is a new bone saving implant that utilizes an implantation technique that reduces the damage to the muscle tissue allowing for patients to have a short recovery time as well as a new design that allows it to rest on the medial cortex. There has been anecdotal evidence that this device leads to early revision within six months of implantation due to failures occurring in the medial cortex. The main goal of this study was to computationally model the Zimmer Fitmore and compare it to the ML Taper to see if the failures are due to the design of the implant. The models were created using CT scans of the implants and the same implantation process was simulated for each. Two sizes for the cortical bone thickness, 4mm and 10mm, were used and contrasted with each other. The 10mm cortical thickness model showed that v the strains experienced by the Zimmer Fitmore femur were higher than that of the ML Taper. The 4mm model did not fully complete the simulation, but the results that were obtained showed an increased strain in Gruen zone 7. These results show that the design, not implantation method, could be to blame for the need for early revision when using the Zimmer Fitmore.

The following paper describes a fall detection and activity monitoring system with position detection based on Zigbee transceivers.The main objective is to reduce the time taken for emergency personnel to respond to falls among the elderly. Especially when the victim is unconscious or delirious, position tracking reduces location determination time within a busy hospital or nursing home environment and facilitates immediate treatment. Reduced response times correlate to decreased morbidity and mortality rates. Background is provided on the major wireless network advances currently deployed in a healthcare setting for asset and personnel tracking, etiology of falls, and several methods of detecting falls using sensors and image processing techniques. Data analysis proves that a precise coordinate tracking system was infeasible using the XBee RF module (based on the Zigbee protocol) due to environmental noise, a poor antenna construction and lack of precise signal strength measurements. A primitive scheme with lower resolution and higher reliability associating a single location with each Zigbee transceiver was employed. A pedometer function was added to the project to monitor the user’s daily activity and to potentially serve as a predictor of falls through the interpretation of mobility and gait patterns related to step counts.

Filtration is a technology that is used almost ubiquitously in society from uses raging from filtration of macroparticles from water to pharmaceutical grade filtration products to remove anything larger than a protein. However, with such a wide range of uses, most filtration products have the same issue; membrane clogging (fouling) that prevents continuous use and requires frequent maintenance. This thesis hypothesizes that by applying a direct current (DC) to an insulating array of posts, they will create a foul-less insulative dielectrophoretic filter (iDEP) that does not clog since particles will levitate above the insulating array. This thesis tested an inherited device (legacy device) and found that its design did not perform the desired foul-less filtration operation under the tested conditions. Therefore, using COMSOL simulations, the conditions of testing and improved deign were developed to fruition. These devices were fabricated and tested and found to successfully levitate yeast particles above the foul-less filtration array using a direct current insulative dielectrophoretic (iDEP) filter. Additionally, different post geometries were observed and how they affect the dielectric force on particles. Although a foul-less filter was not successfully developed over the course of this thesis, the groundwork for development of DC iDEP has been set.

MEASURING IMPEDANCE OF TISSUES USING A MICROFABRICATED MICROELECTRODE ARRAY By Ashwini Bhat This thesis looks at the possibility of using impedance spectroscopy for differentiating tissue, using a microelectrode array (MEA). The thesis first discusses the background and the motivation for this thesis. It covers the certain basic concepts of the human skin starting from the top epidermis layer all the way to the deep dermis layers of the skin. Then it discusses different types of skin cancer and how they occur, in humans. It also discusses various microfabrication techniques such as oxidation, wet etching, sputtering and photolithography for the creation of a MEA in order to test the tissue. The microfabricated MEA is then used to measure impedance across cooked and raw chicken at different frequencies in order to see if the two types of tissues can be differentiated using their respective impedances. The data shows that the MEA was not able to successfully differentiate the two types of the tissues. It does however list multiple improvements in the fabrication of the MEA and improvements that could be made to the testing procedures which could possible give greater difference in impedance between the two tissues

It is a known problem that a Spinal Cord Stimulator (SCS) can interact with an Implantable Cardioverter Defibrillator (ICD) when both devices are implanted in the same patient. Interactions between the SCS and ICD can cause inappropriate therapy which can be harmful to the patient. While ICD devices have a distinct narrowband sensing bandwidth, the pulse configurations that current SCS devices deliver were not designed with this frequency region in mind. In this thesis, I recommend a new pulse configuration for SCS devices that will minimize the interaction between the two devices. I produce a theoretical equation for each pulse configuration in the frequency domain using the Laplace transform and present the results in Matlab. I also design my own SCS device to deliver multiple pulse configurations and use it to gather empirical data. The theoretical and empirical results are used to show the extent of the improvement between the new pulse and existing pulse configurations. The results prove that the new pulse configuration will significantly reduce crosstalk within the desired ICD bandwidth. A reduction in crosstalk will decrease the probability that an SCS will interact with a ICD device.

3-D paper-based microfluidic devices (micoPADs) are small and portable devices made out of paper that offer a promising platform for diagnostic applications outside of a laboratory. These devices are easy to use, low cost, require no power source, and capable of detecting multiple targets simultaneously. The work in this thesis demonstrated the ability of a 3-D paper-microfluidic platform to simultaneously detect 5 targets. Rubber cord stock was used in conjunction with an acrylic housing unit to apply pressure along the edge of the channel. The indirect pressure application was successful in promoting vertical fluid flow between layers. Average channel development times were recorded between 110 seconds and 150 seconds. The implementation of the 3-D paper-microfluidic platform as a diagnostic device was validated with a colorimetric glucose assay. In a novel application, reagents were deposited onto the 3-D platform via a glucose reagent pencil created by Martinez et al. A visual signal was observed for the successful detection of glucose at a concentration of 1.2 mM. These results offer promise for future work in combing new reagent deposition techniques with a multi-layer paper-microfluidic platform. Overall, this research made advancements in the design of a paper-microfluidic platform capable of the simultaneous detection of 5 targets.

In this work, a novel microfluidic cell culture platform capable of automated electrical impedance measurements and immunofluorescence and brightfield microscopy was developed for further in-vitro cellular research intended to optimize cell culture conditions. The microfluidic system design, fabrication, automation, and design verification testing are described. Electrical and optical measurements of the 16 parallel cell culture chambers were automated via a custom LabView interface. A proposed design change will enable gas diffusion, removing the need for an environmental enclosure and allow long-term cell culture experiments. This "lab on a chip" system miniaturizes and automates experiments improving testing throughput and accuracy while creating a highly controllable microenvironment for cell culture. Such a system can be applied to drug development, bioassays, diagnostics, and animal testing alternatives. This work is part of a collaborative effort to define protocols for the electrical and optical characterization of cell culture within a novel microfluidic device with the intent of optimizing microenvironment conditions.

This thesis encompasses a feasibility study of using low-cost materials to manufacture microfluidic chips that can perform the same functions as chips manufactured using traditional methods within an acceptable range of efficiency of chips created with more exotic methods and materials. The major parts of the project are the selection and characterization of the fabrication methods for creating the channels for fluid flow, the methods for sealing the channels to create a usable chip and the electrophoretic separations of carboxylated microspheres of different potentials. In this work we seek to answer the question if laser-etched PMMA microfluidic chips are comparable in functionality to microfluidic chips created with PDMS or glass. In the process of answering this question we will touch on FEA modeling, characterization of the manufacturing process and multiple prototype designs while keeping within the low-cost theme. The purpose of capillary electrophoresis is to separate proteins based on their inherent electric charge. Capillary electrophoresis is a standard chip design used in the microfluidics world to prove a new fabrication method or chip material before branching out to other experiments because it is a fairly simple and robust design. Common problems associated with the manufacturing methods and materials were taken into account such as electroosmotic flow and chip sealing. CZE designs from literature were referenced to create a chip that would separate carboxylated microbeads with reasonable resolution. Wire electrodes were affixed to the chip to induce electric fields for the electrophoresis experiments. The goal of this thesis is to prove the manufacturing methods and attain results within 70% of literature standards.