Polymeric Valve Research Articles

EXPERIMENTAL INVESTIGATION INTO MAGNETORHEOLOGICAL FINISHING OF POLYMER VALVE SEAT SURFACE FOR BALL VALVE PERFORMANCE

A polymer valve seat is an essential component of ball valves. However, a gas pipeline valve leakage during the gas or oil transportation process causes major issues. Therefore, the fine finishing of the polymer valve seat is important. This work describes the effect of the magnetorheological finishing (MRF) process on the surface characteristics of the polymer valve seat. To achieve a finely finished polymer valve seat surface, the best process parametric combination of current, workpiece rotational, and tool rotational speed are obtained using the response surface methodology. The optimum process parameters are further used to enhance surface characteristics (including surface roughness, microhardness, and surface morphology) through fine finishing. Using the optimum process conditions, the surface roughness was reduced to 110[Formula: see text]nm from 570[Formula: see text]nm in 140[Formula: see text]min of finishing on a 4878[Formula: see text]mm2 surface area of the polymer valve seat. The circularity of the valve seat surface’s dimensional correctness is investigated further. The current MRF process can fine-finish the polymer valve seat surface consistently, resulting in improved surface characteristics and functional performance.

Low protein adsorption and high cellular activity of PEG-based silicone polyurethane for artificial heart valves

Polyurethane have the advantages of convenient structural design, low production cost, and excellent mechanical compatibility, and is expected to be used as a polymer heart valve material. However, its development in biomaterials is limited because it is prone to hydrolysis and coagulation after long-term implantation in organisms. In this study, "PEG-MDI-PEG" macromolecular diol was prepared by structural design of the soft segment of polyurethane. Copolymerization with telechelic α,ω-bis(6-hydroxyethoxypropyl)-PDMS as mixed soft segment, prepolymer solution was prepared by solution polymerization, and the biocompatibility of silicone-based polyurethane obtained by casting was characterized. By adjusting the feed ratio to control the silicon content in the copolymer, when the silicon content was 60 %, the protein adsorption capacity was 75 % lower than that of unmodified polyurethane, and the cell activity was more than 80 %, which was a useful characteristic for silicon-based polyurethane as a potential polymer valve material.

Cardiac valve scaffold design: Implications of material properties and geometric configuration on performance and mechanics

Development of tissue engineered scaffolds for cardiac valve replacement is nearing clinical translation. While much work has been done to characterize mechanical behavior of native and bioprosthetic valves, and incorporate those data into models improving valve design, similar work for degradable valve scaffolds is lacking. This is particularly important given the implications mechanics have on short-term survival and long-term remodeling. As such, this study aimed to characterize spatially-resolved strain profiles on the leaflets of degradable polymeric valve scaffolds, manipulating common design features such as material stiffness by blending poly(carbonate urethane)urea with stiffer polymers, and geometric configuration, modeled after either a clinically-used valve design (Mk1 design) or an anatomically “optimized” design (Mk2 design). It was shown that material stiffness plays a significant role in overall valve performance, with the stiffest valve groups showing asymmetric and incomplete opening during systole. However, the geometric configuration had a significantly greater effect on valve performance as well as strain magnitude and distribution. Major findings in the strain maps included systolic strains having overall higher strain magnitudes than diastole, and peak radial-direction strain concentrations in the base region of Mk1 valves during systole, with a significant mitigation of radial strain in Mk2 valves. The high tunability of tissue engineered scaffolds is a great advantage for valve design, and the results reported here indicate that design parameters have significant and unequal impact on valve performance and mechanics.

Prosthetic heart valves for transcatheter aortic valve replacement

AbstractTranscatheter aortic valve replacement (TAVR) has the advantages of less trauma and faster postoperative recovery, which has brought the possibility to the elderly patient with valvular heart disease and is gradually replacing surgical aortic valve replacement (SAVR). The interventional valve used in TAVR needs to be compressed and transported through the catheter to the lesion site, and can still recover its original shape, structure and performance. This process requires that the material should be flexible, and the rigid mechanical valves in SAVR are not suitable. Recently, decellularized biological valves have been widely used in clinical practice, but their poor durability causes a limitation for long‐term implantation. Therefore, the anti‐calcification modification of biological valves and the design of new polymeric valves with good biostability have gained considerable attention. This review summarizes the calcification mechanism of biological valves and the research progress in anti‐calcification modification strategies. Besides, the development of new polymeric valves is included, with special attention to representative cases, such as polysiloxane, polytetrafluorethylene, poly(styrene‐block‐isobutylene‐block‐styrene), and polyurethane‐based materials. Finally, the challenges and future perspectives of artificial heart valve materials are discussed.

Design consideration of a novel polymeric transcatheter heart valve through computational modeling

Transcatheter heart valve replacement is becoming a more routine procedure, and this is further supported by positive outcomes from studies involving low-risk patients. Nevertheless, the lack of long-term transcatheter heart valve (TAV) durability is still one of the primary concerns. As a result, more research has been focused on improving durability through various methods such as valve design, computational modeling, and material selection. Recent advancements in polymeric valve fabrication showed that linear low-density polyethylene (LLDPE) could be used as leaflet material for transcatheter heart valves. In this paper, a parametric study of computational simulations showed stress distribution on the leaflets of LLDPE-TAV under diastolic load, and the results were used to improve the stent design. The in silico experiment also tested the effect of shock absorbers in terms of valve durability. The results demonstrated that altering specific stent angles can significantly lower peak stress on the leaflets (13.8 vs. 6.07 MPa). Implementing two layers of shock absorbers further reduces the stress value to 4.28 MPa. The pinwheeling index was assessed, which seems to correlate with peak stress. Overall, the parametric study and the computational method can be used to analyze and improve valve durability.

Polymer Components for Paper‐Based Analytical Devices

AbstractIn recent years, paper has become an essential substrate material for developing different types of sensors, from wearable devices to single‐use test strips and biosensors. In parallel, a polymer‐based toolbox has emerged in order to add additional functions to these paper‐based analytical devices. In this article, examples are compiled from the recent literature showing microfluidic systems based on printing impermeable polymer barriers with different methods as well as the implementation of electrochemical, fluorescent, and colorimetric polymer‐based transducers in paper‐based analytical platforms. Externally actuated or dissolvable polymer valves and reservoirs, analyte concentrators, and separation devices, as well as polymer‐based recognition elements (molecularly imprinted polymers) printed on paper substrates are also reviewed. The search has revealed a plethora of possibilities for developing complex lab‐on‐chip devices implementing different polymer‐based components in them. The ability of patterning these polymers with common printing methods that do not require specialized facilities paves the way for mass producing this kind of advanced paper‐based analytical device.

Visions of TAVR Future: Development and Optimization of a Second Generation Novel Polymeric TAVR.

Tissue-based transcatheter aortic valve (AV) replacement (TAVR) devices have been a breakthrough approach for treating aortic valve stenosis. However, with the expansion of TAVR to younger and lower risk patients, issues of long-term durability and thrombosis persist. Recent advances in polymeric valve technology facilitate designing more durable valves with minimal in vivo adverse reactions. We introduce our second-generation polymeric transcatheter aortic valve (TAV) device, designed and optimized to address these issues. We present the optimization process of the device, wherein each aspect of device deployment and functionality was optimized for performance, including unique considerations of polymeric technologies for reducing the volume of the polymer material for lower crimped delivery profiles. The stent frame was optimized to generate larger radial forces with lower material volumes, securing robust deployment and anchoring. The leaflet shape, combined with varying leaflets thickness, was optimized for reducing the flexural cyclic stresses and the valve's hydrodynamics. Our first-generation polymeric device already demonstrated that its hydrodynamic performance meets and exceeds tissue devices for both ISO standard and patient-specific in vitro scenarios. The valve already reached 900 × 106 cycles of accelerated durability testing, equivalent to over 20 years in a patient. The optimization framework and technology led to the second generation of polymeric TAV design- currently undergoing in vitro hydrodynamic testing and following in vivo animal trials. As TAVR use is rapidly expanding, our rigorous bio-engineering optimization methodology and advanced polymer technology serve to establish polymeric TAV technology as a viable alternative to the challenges facing existing tissue-based TAV technology.

Design of an aortic polymeric valve with asymmetric leaflets and evaluation of its performance by finite element method

BackgroundThe geometry of leaflets plays a significant role in prosthetic valves’ (PVs) performance. Typically, natural aortic valves have three unequal leaflets, which differ in size. The present study aims to design an asymmetric tri-leaflet polymeric valve with one large and two small leaflets based on commissure lengths and leaflet eccentricities. MethodsEccentricity was related to commissure lengths based on the deformation of the free margins for the fully-opened state of leaflets. The polystyrene-block-polyethylene-polypropylene-block-polystyrene polymer characterized the material properties of the leaflets. The Finite Element Method (FEM) was used to evaluate performance parameters, including maximum geometric orifice area (GOA), average GOA, maximum von Mises stress, and leaflet's coaptation surface area (CSA). ResultsAsymmetric valves with no eccentricity provided a low level of GOA because the asymmetric form of small leaflets caused them to close faster than the large leaflet, leading to a sudden drop in the GOA during systole. As the radial curve tends towards a straight line, an undesirable coaptation occurs, and peak stress increases despite higher GOAs. A new radial curve consisting of two straight lines connected by an arc that provided 25.64 mm2 coaptation surface area (CAS) and 117.54 mm2 average GOA, was proposed to improve coaptation and GOA. ConclusionThe radial curve of leaflets affects the valve's performance more than other geometric parameters. The combination of straight lines and arcs for radial curves was selected as the reference model for asymmetric valves with one large and two small leaflets.

Dissolvable Polymer Valves for Sweat Chrono-Sampling in Wearable Paper-Based Analytical Devices.

Paper sensors with colorimetric signal transduction mechanisms are promising for developing single-use wearable patches that only require a smartphone to quantify signals. However, measuring biomarker fluctuations with colorimetric wearable sensors requires implementing a chrono-sampling method for performing sequential measurements. In this article, we report on a chrono-sampling method that enables the fabrication of wearable devices made entirely of filter paper. It consists of using dried polymers as closed valves that deflect the flow of liquids to different transducers of a multisensor. As time passes by, the polymer dissolves and the valve opens. The sequential opening of the valves results in a succession of measurements that reveals fluctuations in the concentration of the target analyte. This concept was demonstrated with a paper multisensor capable of performing nine consecutive pH measurements. The device was also adapted for developing a urea biosensor that detects pH measurements generated by the hydrolysis of the analyte catalyzed by urease. The proposed analytical platform could monitor the pH of sweat with an accuracy and precision comparable to a laboratory-based method when worn during an exercise routine. The results shown here pave the way for developing colorimetric wearable biosensors that measure variations in the concentration of biomarkers such as glucose, lactate, creatinine, or uric acid over time.

Investigation the effect of geometry and position of polymeric heart valves on hemodynamic with fluid-structure interaction numerical method

Computational modeling and numerical simulation of heart valve dynamics incorporating both fluid dynamics and valve structural replications has been challenging. In this study, we developed a double-coupled fluid-structure interaction (FSI) model using arbitrary lagrangian eulerian(ALE) and steered adaptive mesh(SAM). So we were looking to simulate transcatheter aortic valve (TAV) hemodynamic performance throughout entire cardiac cycles [1]. To reach this object, semi-real geometry of aorta and aortic polymeric valves has been created. At model inlet, left ventricular pressure and at the model outlet the elastic porous tube have been considered. Nonlinear finite element way and Sparse solver was utilized to couple fluid and solid equation. Consequently, extensive and comparative simulation were performed to investigate the impact of valve elasticity and valve positions on hemodynamics and solid parameters. Effective Orifice Area(EOA) also has been calculated [1]. The simulation results indicated that the lower of the elastic modulus cause to increase the EOA. Furthermore, the result of valve position showed, whenever the valve is closer to sinuses, a greater EOA and lower stresses impose on the leaflet are achievable.

Polymeric valves appearing on the transcatheter horizon

Polymeric valves appearing on the transcatheter horizon

Performance of Novel Polymer Heart Valve in Ovine Mitral Model

Objective: Evaluate the performance, hemocompatibility and histopathological consequences of a novel polymer mitral valve implant compared to Carpentier-Edwards bovine pericardial valve in an ovine model. This polymer valve (silicone polyurethan urea) was previously compared to bovine pericardial valve in the aortic position and found to be equivalent. Methods: Four sheep underwent thoracotomy open heart surgery on cardiopulmonary bypass in which both anterior and posterior mitral leaflets were excised and a patented polymer heart valve was implanted. The control group had implant of a bovine pericardial valve. Post-operative transthoracic echocardiograms were performed to evaluate valve function on post-op days 7-14, 30, 60 and pre-termination at 90 days. Blood samples for hematologic and chemistry measurements were obtained on the same schedule. Gross and histological examination of the valves was done after excision on POD 90. Histological exam of the heart, brain, kidneys and liver were done to identify potential embolic injury. Enoxaparin was given from POD 4 to POD 42. Results: Serial echocardiographic measurements showed comparable values between pre-operative and post-operative studies. There were no significant changes in blood test results in either group. The polymer valve leaflets were free of pannus, calcium-mineralization, shrinkage, endothelium or reduction in pliability. There was appropriate endothelialization and fibrosis at each tissue/frame interface. The bovine pericardial valve results were similar with the exception of fibrous pannus extending onto leaflet surface. Conclusions: The novel polymer mitral valve has a functional and safety profile that is similar to a bovine pericardial valve. However, the polymer valve has no cellular or thrombotic debris on its leaflets. It appears to be safe for human implants.

Fabrication and in-vitro characterization of a polymeric aortic valve for minimally invasive valve replacement

The valve replacement therapy is the standard treatment for severe heart valve diseases. Nowadays, two types of commercial prosthesis are available: mechanical and biological, but both of them have severe limitations. Moreover, alternative therapeutic approach for valve replacement, based on minimally invasive techniques (MIAVR), motivates the search for new valve materials. In this study a polyurethane-based self-expandable tri-leaflets heart valve compatible with MIAVR procedure is proposed. The device is based on the development, fabrication and characterization of three different elements: the leaflets, the polymeric stent for supporting the leaflets, and the external metallic stent for anchoring the valve to the native aortic root. The polymeric stent and the valve leaflets were fabricated using a thermoplastic silicone-polycarbonate-urethane using 3D printing and spray technology while the external metallic stent was made in nickel titanium (Nitinol) to obtain a self-expandable valve after the crimping process. The three elements were assembled in the completed device and tested by crimping, fatigue and fluid-dynamic test. The novel polymeric valve proposed showed promising results about valve crimping capabilities, durability and fluid dynamic performances. This approach could offer advantages such as low cost and to produce a tailor-made device basing on patient's imaging data. Moreover, the selected biomaterial offers the potential to have a device that could need of permanent anticoagulation and lack of calcification.

Abstract 14086: Early Results of a Novel EPTFE-based Pulmonary Valved Conduit in a Pediatric Patient Population

Introduction: This prospective, multicenter, single-arm, early feasibility study evaluates the safety and performance of an investigational ePTFE-based valve for replacement of the pulmonary valve and reconstruction of the Right Ventricular Outflow Tract. A novel polymeric pulmonary valved conduit, resistant to calcification and structural valve deterioration, may provide a more durable therapy option for the pediatric population by preventing loss of right ventricular function and increased freedom from valve-related reintervention and mortality. Methods: The primary endpoints at 6 months adjudicated by an independent Clinical Events Committee are valve-related mortality and device-related reintervention. The investigational device is a valved conduit comprised of ePTFE with stretch technology and a flexible tri-leaflet polymeric valve made of an advanced proprietary composite material, which can be tailored to length requirements of the anatomy. All enrolled patients met study inclusion/exclusion criteria and had a signed informed consent form. All patients had pre- and postoperative evaluation via transthoracic echocardiography (TTE). Aspirin was administered for a minimum of three months post procedure and, per institutional protocols, four patients were on temporary Coumadin. Results: Of the 17 patients enrolled from three sites, 52.9% were male. Ages ranged from 6 to 17 years (mean 11.5 ± 3.7). BSA ranged from 0.82 to 1.57 m 2 . At six months follow up, 100% of subjects successfully met the primary endpoint of freedom from valve-related mortality and device-related reintervention. No patient exhibited an RVOT gradient > 20 mmHg. No patients had pulmonary regurgitation above baseline (≤ mild) observed through six months. Throughout postoperative serial TTE evaluation at discharge, 1, 3, and 6 months, no evidence of worsening valvular insufficiency was observed. No patient developed endocarditis and TTE detected no clinically significant thrombus formation. Conclusions: These preliminary data of a novel Pulmonary Valve Conduit suggest improved pulmonic and right ventricular function based on TTE measurements, no unexpected findings, no valve-related adverse events and encouraging hemodynamic performance through 6 months.

In Vitro Durability and Stability Testing of a Novel Polymeric Transcatheter Aortic Valve.

Transcatheter aortic valve replacement (TAVR) has emerged as an effective therapy for the unmet clinical need of inoperable patients with severe aortic stenosis (AS). Current clinically used tissue TAVR valves suffer from limited durability that hampers TAVR's rapid expansion to younger, lower risk patients. Polymeric TAVR valves optimized for hemodynamic performance, hemocompatibility, extended durability, and resistance to calcific degeneration offer a viable solution to this challenge. We present extensive in vitro durability and stability testing of a novel polymeric TAVR valve (PolyNova valve) using 1) accelerated wear testing (AWT, ISO 5840); 2) calcification susceptibility (in the AWT)-compared with clinically used tissue valves; and 3) extended crimping stability (valves crimped to 16 Fr for 8 days). Hydrodynamic testing was performed every 50M cycles. The valves were also evaluated visually for structural integrity and by scanning electron microscopy for evaluation of surface damage in the micro-scale. Calcium and phosphorus deposition was evaluated using micro-computed tomography (μCT) and inductive coupled plasma spectroscopy. The valves passed 400M cycles in the AWT without failure. The effective orifice area kept stable at 1.8 cm with a desired gradual decrease in transvalvular pressure gradient and regurgitation (10.4 mm Hg and 6.9%, respectively). Calcium and phosphorus deposition was significantly lower in the polymeric valve: down by a factor of 85 and 16, respectively-as compared to a tissue valve. Following the extended crimping testing, no tears nor surface damage were evident. The results of this study demonstrate the potential of a polymeric TAVR valve to be a viable alternative to tissue-based TAVR valves.

Characterization of a reversible thermally-actuated polymer-valve: A potential dynamic treatment for congenital diaphragmatic hernia.

BackgroundCongenital diaphragmatic hernia (CDH) is a fetal defect comprising an incomplete diaphragm and the herniation of abdominal organs into the chest cavity that interfere with fetal pulmonary development. Though the most promising treatment for CDH is via interventional fetoscopic tracheal occlusion (TO) surgery in-utero, it has produced mixed results due to the static nature of the inserted occlusion. We hypothesize that a suitable noninvasively-actuatable, cyclic-release tracheal occlusion device can be developed to enable dynamic tracheal occlusion (dTO) implementation.ObjectiveTo conduct an in-vitro proof-of-concept investigation of the construction of thermo-responsive polymer valves designed for targeted activation within a physiologically realizable temperature range as a first step towards potential development of a noninvasively-actuatable implantable device to facilitate dynamic tracheal occlusion (dTO) therapy.MethodsSix thermo-responsive polymer valves, with a critical solution temperature slightly higher than normal physiological body temperature of 37°C, were fabricated using a copolymer of n-isopropylacrylamide (NIPAM) and dimethylacrylamide (DMAA). Three of the valves underwent ethylene oxide (EtO) sterilization while the other three served as controls for EtO-processing compatibility testing. Thermal response actuation of the valves and their steady-state flow performances were evaluated using water and caprine amniotic fluid.ResultsAll six valves consisting of 0.3-mole fraction of DMAA were tested for thermal actuation of caprine amniotic fluid flow at temperatures ranging from 30–44°C. They all exhibited initiation of valve actuation opening at ~40°C with full completion at ~44°C. The overall average coefficient of variation (CV) for the day-to-day flow performance of the valves tested was less than 12%. Based on a Student t-test, there was no significant difference in the operational characteristics for the EtO processed versus the non-EtO processed valves tested.ConclusionsWe successfully fabricated and demonstrated physiological realizable temperature range operation of thermo-responsive polymer valves in-vitro and their suitability for standard EtO sterilization processing, a prerequisite for future in-vivo surgical implantation testing.

Comparative Fluid-Structure Interaction Analysis of Polymeric Transcatheter and Surgical Aortic Valves' Hemodynamics and Structural Mechanics.

Transcatheter aortic valve replacement (TAVR) has emerged as an effective alternative to conventional surgical aortic valve replacement (SAVR) in high-risk elderly patients with calcified aortic valve disease. All currently FDA-approved TAVR devices use tissue valves that were adapted to but not specifically designed for TAVR use. Emerging clinical evidence indicates that these valves may get damaged during crimping and deployment- leading to valvular calcification, thrombotic complications, and limited durability. This impedes the expected expansion of TAVR to lower-risk and younger patients. Viable polymeric valves have the potential to overcome such limitations. We have developed a polymeric SAVR valve, which was optimized to reduce leaflet stresses and offer a thromboresistance profile similar to that of a tissue valve. This study compares the polymeric SAVR valve's hemodynamic performance and mechanical stresses to a new version of the valve- specifically designed for TAVR. Fluid-structure interaction (FSI) models were utilized and the valves' hemodynamics, flexural stresses, strains, orifice area, and wall shear stresses were compared. The TAVR valve had 42% larger opening area and 27% higher flow rate versus the SAVR valve, while wall shear stress distribution and mechanical stress magnitudes were of the same order, demonstrating the enhanced performance of the TAVR valve prototype. The TAVR valve FSI simulation and Vivitro pulse duplicator experiments were compared in terms of the leaflets' kinematics and the effective orifice area. The numerical methodology presented can be further used as a predictive tool for valve design optimization for enhanced hemodynamics and durability.

Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study.

Transcatheter aortic valve replacement (TAVR) is a minimally-invasive approach for treating severe aortic stenosis. All clinically-used TAVR valves to date utilize chemically-fixed xenograft as the leaflet material. Inherent limitation of the tissue (e.g., calcific degeneration) motivates the search for alternative leaflet material. Here we introduce a novel polymeric TAVR valve that was designed to address the limitations of tissue-valves. In this study, we experimentally evaluated the hemodynamic performance of the valve and compared its performance to clinically-used valves: a gold standard surgical tissue valve, and a TAVR valve. Our comparative testing protocols included: (i) baseline hydrodynamics (ISO:5840-3), (ii) complementary patient-specific hydrodynamics in a dedicated system, and (iii) thrombogenicity. The patient-specific testing system facilitated comparing TAVR valves performance under more realistic conditions. Baseline hydrodynamics results at CO 4-7L/min showed superior effective orifice area (EOA) for the polymer valve, most-notably as compared to the reference TAVR valve. Regurgitation fraction was higher in the polymeric valve, but within the ISO minimum requirements. Thrombogenicity trends followed the EOA results with the polymeric valve being the least thrombogenic, and clinical TAVR being the most. Hemodynamic-wise, the results strongly indicate that our polymeric TAVR valve can outperform tissue valves.

(Keynote) New Microfluidic Platforms for Medical Screening and Diagnostics

I. Introduction The field of microfluidics continues to show promise for applications in medical screening and diagnostics, and the study of human health and disease. Microfluidics has the potential to miniaturize instrumentation usually limited to the laboratory table top, offering the possibility of highly portable or wearable instruments for medical screening and diagnostics including the monitoring of biomarkers in real time. Microfluidics also offers unique devices and methods that enable scientists to study health and disease in new ways, from studying individual and monolayers of biological cells to mimicking organs on a chip. In order to fully develop these applications, new microfluidic platforms are required that incorporate the results of ongoing research in fields such as materials, biology, microfabrication, electronics, and computer engineering. This presentation discusses several platforms for the development of microfluidic systems for applications in biomedicine and biology. These platforms employ multiple recent advances in nanocomposite polymers, polymer microfabrication, printed circuit board technology, reconfigurable systems, and flexible electronics. These platforms are employed toward the development of new microfluidic instruments, including a reconfigurable microfluidic diagnostic unit, inexpensive and flexible biomedical screening devices, and biological cell research platforms. II. Example Platforms A. Reconfigurable Microfluidic Platform There is a growing need for instruments that perform fast, accurate, and inexpensive biological sample manipulation and processing with high-throughput. Microfluidics offers great possibilities for small, portable systems to perform fast manipulation and sorting of large numbers of samples, as well as multiplexed analysis of a single sample. Successful microfluidic-based devices exist, but their portability and throughput has been limited as they either require separate microfluidic channels for each test, which translates to a large array of permanently configured channels with a large footprint; require large off-chip support devices; or are based on other technologies that have relatively strict requirements for fluid sample manipulation and sample transfer between devices. We present on-going work to develop an instrument to address these problems of simultaneous high-throughput and portability. This instrument, a collaboration between microfluidics and computer engineering labs at Simon Fraser University, offers a new approach that is accomplished through the merging of electronically controlled functional magnetic materials for microfluidics with state-of-the-art field programmable technology. The instrument employs a compact, reconfigurable, microfluidics platform that is a combination of an array of small, individually-programmable, magnetic polymer valves [1] to address microfluidic channels that connect chambers containing sensors [2], heaters [3], mixers [4], etc., and a field programmable technology control that allows the highly portable instrument to configure itself “on-the-fly” for analysis of multiple samples using multiple tests. We present the reconfigurable microfluidics unit paradigm, and discuss technologies and techniques taken from the fields of composite materials and polymer microfabrication to develop the hardware for the reconfigurable microfluidic platform. B. Cost-Effective PCB-Based Platforms Printed Circuit Board (PCB) technology is a well understood and well utilized platform for electronics. We present a new PCB-based platform for microfluidic biomedical and biological testing. The standardized platform features integrated functional units, three-dimensional (3D) configurations, convenient device-instrumentation interconnections, and industry-compatible precision manufacturing using a custom three-metal fabrication process. PCB technology is demonstrated to not only form an integrated platform but is also utilized in the fabrication of functional elements for biosensing and bioprocessing devices and systems, such as reconfigurable microfluidic systems for biosample analysis. Example elements include a chemistry-based enzyme assay [2], and a molecule-based quantitative polymerase chain reaction (qPCR) screening device [3]. C. Flexible Microfluidic Platforms We present our most recent work in the development of microfluidic instruments of flexible substrates. We have previously presented work on flexible microfluidic platforms containing multiple layers of interconnected microfluidic channels on flexible substrates [5, 6], as well as conductive and magnetic functional polymers for flexible sensor [7] and actuator devices [1, 2, 8]. We present now the concept of integrating these technologies towards development of flexible microfluidic instrumentation for biological cell research [9] and wearable biomedical monitors. References M. Rahbar, et. al., J Micromech Microeng 26(5), 055012 (2016).H.-Y. Tseng, et. al., Measurement 73:158-161 (2015).H.-Y. Tseng, et. al. Sensors Actuators B, 204:459-466 (2014).M. Rahbar, et. al., J Micromech Microeng, 24(2):025003 (2014).D. Chung & B.L. Gray, J Micromech Microeng, 27(11), (2017).6. Patel, et. al., J Micromech Microeng 23(6):065029 (2013).D. Chung, et. al., J Electrochemical Society 161(2):B3071-76 (2014).M. Rahbar & B.L. Gray, IEEE 17th International Conference on Nanotechnology (IEEE-NANO), Pittsburgh, (July 2017).B.L. Gray, et. al., IEEE 14th International Conference on Nanotechnology (IEEE-NANO), Toronto (August 2014), 986-990.

Super-Absorbent Polymer Valves and Colorimetric Chemistries for Time-Sequenced Discrete Sampling and Chloride Analysis of Sweat via Skin-Mounted Soft Microfluidics.

This paper introduces super absorbent polymer valves and colorimetric sensing reagents as enabling components of soft, skin-mounted microfluidic devices designed to capture, store, and chemically analyze sweat released from eccrine glands. The valving technology enables robust means for guiding the flow of sweat from an inlet location into a collection of isolated reservoirs, in a well-defined sequence. Analysis in these reservoirs involves a color responsive indicator of chloride concentration with a formulation tailored to offer stable operation with sensitivity optimized for the relevant physiological range. Evaluations on human subjects with comparisons against ex situ analysis illustrate the practical utility of these advances.