RESUMO
Flow-induced vibrations (FIV) were considered as unwanted vibrations analogous to noise. However, in a recent trend, the energy of these vibrations can be harvested and converted to electrical power. In this study, the potential of FIV as a source of renewable energy is highlighted through experimental and numerical analyses. The experimental study was conducted on an elastically mounted circular cylinder using helical and leaf springs in the wind tunnel. The Reynolds number (Re) varied between 2300-16000. The motion of the cylinder was restricted in all directions except the transverse direction. The micro-electromechanical system (MEMS) was mounted on the leaf spring to harvest the mechanical energy. Numerical simulations were also performed with SST k-ω turbulence model to supplement the experiments and were found to be in good agreement with the experimental results. The flow separation and vortex shedding induce aerodynamic forces in the cylinder causing it to vibrate. 2S vortex shedding pattern was observed in all of the cases in this study. The maximum dimensionless amplitude of vibration (A/D) obtained was 0.084 and 0.068 experimentally and numerically, respectively. The results showed that the region of interest is the lock-in region where maximum amplitude of vibration is observed and, therefore, the maximum power output. The piezoelectric voltage and power output were recorded for different reduced velocities (Ur = 1-10) at different resistance values in the circuit. It was observed that as the amplitude of oscillation of the cylinder increases, the voltage and power output of the MEMS increases due to high strain in piezoelectric transducer. The maximum output voltage of 0.6V was observed at Ur = 4.95 for an open circuit, i.e., for a circuit with the resistance value of infinity. As the resistance value reduced, a drop in voltage output was observed. Maximum power of 10.5µW was recorded at Ur = 4.95 for a circuit resistance of 100Ω.
Assuntos
Transdutores , Vibração , Modelos Teóricos , Energia Renovável , Sistemas Microeletromecânicos/instrumentação , Simulação por ComputadorRESUMO
Nanoelectromechanical systems (NEMS)-based mass spectrometry (MS) is an emerging technique that enables determination of the mass of individual adsorbed particles by driving nanomechanical devices at resonance and monitoring the real-time changes in their resonance frequencies induced by each single molecule adsorption event. We incorporate NEMS into an Orbitrap mass spectrometer and report our progress towards leveraging the single-molecule capabilities of the NEMS to enhance the dynamic range of conventional MS instrumentation and to offer new capabilities for performing deep proteomic analysis of clinically relevant samples. We use the hybrid instrument to deliver E.â coli GroEL molecules (801â kDa) to the NEMS devices in their native, intact state. Custom ion optics are used to focus the beam down to 40â µm diameter with a maximum flux of 25â molecules/second. The mass spectrum obtained with NEMS-MS shows good agreement with the known mass of GroEL.
Assuntos
Chaperonina 60 , Escherichia coli , Nanotecnologia , Chaperonina 60/química , Espectrometria de Massas , Sistemas Microeletromecânicos/instrumentação , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/análiseRESUMO
Thin-film piezoelectric micromachined ultrasound transducers (PMUTs) are an increasingly relevant and well-researched field, and their biomedical importance has been growing as the technology continues to mature. This review article briefly discusses their history in biomedical use, provides a simple explanation of their principles for newer readers, and sheds light on the materials selection for these devices. Primarily, it discusses the significant applications of PMUTs in the biomedical industry and showcases recent progress that has been made in each application. The biomedical applications covered include common historical uses of ultrasound such as ultrasound imaging, ultrasound therapy, and fluid sensing, but additionally new and upcoming applications such as drug delivery, photoacoustic imaging, thermoacoustic imaging, biometrics, and intrabody communication. By including a device comparison chart for different applications, this review aims to assist microelectromechanical systems (MEMS) designers that work with PMUTs by providing a benchmark for recent research works. Furthermore, it puts forth a discussion on the current challenges being faced by PMUTs in the biomedical field, current and likely future research trends, and opportunities for PMUT development areas, as well as sharing the opinions and predictions of the authors on the state of this technology as a whole. The review aims to be a comprehensive introduction to these topics without diving excessively deep into existing literature.
Assuntos
Desenho de Equipamento , Transdutores , Ultrassonografia , Ultrassonografia/instrumentação , Ultrassonografia/métodos , Humanos , Sistemas Microeletromecânicos/instrumentação , Microtecnologia/instrumentaçãoRESUMO
The rational integration of many microfluidic chips and micropumps remains challenging. Due to the integration of the control system and sensors in active micropumps, they have unique advantages over passive micropumps when integrated into microfluidic chips. An active phase-change micropump based on complementary metal-oxide-semiconductor-microelectromechanical system (CMOS-MEMS) technology was fabricated and studied theoretically and experimentally. The micropump structure is simple and consists of a microchannel, a series of heater elements along the microchannel, an on-chip control system, and sensors. A simplified model was established to analyze the pumping effect of the traveling phase transition in the microchannel. The relationship between pumping conditions and flow rate was examined. Based on the experimental results, the maximum flow rate of the active phase-change micropump at room temperature is 22 µL/min, and long-term stable operation can be achieved by optimizing heating conditions.
Assuntos
Sistemas Microeletromecânicos , Técnicas Analíticas Microfluídicas , Sistemas Microeletromecânicos/instrumentação , Sistemas Microeletromecânicos/métodos , Microfluídica/instrumentação , Microfluídica/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Óxidos/química , SemicondutoresRESUMO
Myosin Light Chain (MLC) regulates platelet contraction through its phosphorylation by Myosin Light Chain Kinase (MLCK) or dephosphorylation by Myosin Light Chain Phosphatase (MLCP). The correlation between platelet contraction force and levels of MLC phosphorylation is unknown. We investigate the relationship between platelet contraction force and MLC phosphorylation using a novel microelectromechanical (MEMS) based clot contraction sensor (CCS). The MLCK and MLCP pair were interrogated by inhibitors and activators of platelet function. The CCS was fabricated from silicon using photolithography techniques and force was validated over a range of deflection for different chip spring constants. The force of platelet contraction measured by the clot contraction sensor (CCS) was compared to the degree of MLC phosphorylation by Western Blotting (WB) and ELISA. Stimulators of MLC phosphorylation produced higher contraction force, higher phosphorylated MLC signal in ELISA and higher intensity bands in WB. Inhibitors of MLC phosphorylation produced the opposite. Contraction force is linearly related to levels of phosphorylated MLC. Direct measurements of clot contractile force are possible using a MEMS sensor platform and correlate linearly with the degree of MLC phosphorylation during coagulation. Measured force represents the mechanical output of the actin/myosin motor in platelets regulated by myosin light chain phosphorylation.
Assuntos
Plaquetas/fisiologia , Sistemas Microeletromecânicos/métodos , Testes de Função Plaquetária/métodos , Algoritmos , Técnicas Biossensoriais , Plaquetas/ultraestrutura , Ensaio de Imunoadsorção Enzimática , Sistemas Microeletromecânicos/instrumentação , Modelos Teóricos , Cadeias Leves de Miosina/metabolismo , Fosforilação , Testes de Função Plaquetária/instrumentaçãoRESUMO
Human motions, such as joint/spinal bending or stretching, often contain information that is useful for orthopedic/neural disease diagnosis, rehabilitation, and prevention. Here, we show a badge-reel-like stretch sensing device with a grating-structured triboelectric nanogenerator exhibiting a stretching sensitivity of 8 V mm-1, a minimum resolution of 0.6 mm, a low hysteresis, and a high durability (over 120 thousand cycles). Experimental and theoretical investigations are performed to define the key features of the device. Studies from human natural daily activities and exercise demonstrate the functionality of the sensor for real-time recording of knee/arm bending, neck/waist twisting, and so on. We also used the device in a spinal laboratory, monitoring human subjects' spine motions, and validated the measurements using the commercial inclinometer and hunchback instrument. We anticipate that the lightweight, precise and durable stretch sensor applied to spinal monitoring could help mitigate the risk of long-term abnormal postural habits induced diseases.
Assuntos
Articulações/fisiologia , Amplitude de Movimento Articular/fisiologia , Coluna Vertebral/fisiologia , Dispositivos Eletrônicos Vestíveis , Sistemas Computacionais , Desenho de Equipamento , Humanos , Cifose/diagnóstico , Cifose/fisiopatologia , Sistemas Microeletromecânicos/instrumentação , Monitorização Fisiológica/instrumentação , Movimento/fisiologia , Postura/fisiologiaRESUMO
Energy autonomy and conformability are essential elements in the next generation of wearable and flexible electronics for healthcare, robotics and cyber-physical systems. This study presents ferroelectric polymer transducers and organic diodes for imperceptible sensing and energy harvesting systems, which are integrated on ultrathin (1-µm) substrates, thus imparting them with excellent flexibility. Simulations show that the sensitivity of ultraflexible ferroelectric polymer transducers is strongly enhanced by using an ultrathin substrate, which allows the mounting on 3D-shaped objects and the stacking in multiple layers. Indeed, ultraflexible ferroelectric polymer transducers have improved sensitivity to strain and pressure, fast response and excellent mechanical stability, thus forming imperceptible wireless e-health patches for precise pulse and blood pressure monitoring. For harvesting biomechanical energy, the transducers are combined with rectifiers based on ultraflexible organic diodes thus comprising an imperceptible, 2.5-µm thin, energy harvesting device with an excellent peak power density of 3 mW·cm-3.
Assuntos
Fontes de Energia Bioelétrica , Técnicas Biossensoriais/instrumentação , Eletrônica Médica/instrumentação , Transdutores , Dispositivos Eletrônicos Vestíveis , Técnicas Biossensoriais/métodos , Eletrônica Médica/métodos , Humanos , Sistemas Microeletromecânicos/instrumentação , Sistemas Microeletromecânicos/métodos , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Reprodutibilidade dos Testes , Robótica/instrumentação , Robótica/métodosRESUMO
Investigation of neural circuit dynamics is crucial for deciphering the functional connections among regions of the brain and understanding the mechanism of brain dysfunction. Despite the advancements of neural circuit models in vitro, technologies for both precisely monitoring and modulating neural activities within three-dimensional (3D) neural circuit models have yet to be developed. Specifically, no existing 3D microelectrode arrays (MEAs) have integrated capabilities to stimulate surrounding neurons and to monitor the temporal evolution of the formation of a neural network in real time. Herein, we present a 3D high-density multifunctional MEA with optical stimulation and drug delivery for investigating neural circuit dynamics within engineered 3D neural tissues. We demonstrate precise measurements of synaptic latencies in 3D neural networks. We expect our 3D multifunctional MEA to open up opportunities for studies of neural circuits through precise, in vitro investigations of neural circuit dynamics with 3D brain models.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Sistemas Microeletromecânicos/métodos , Rede Nervosa/fisiologia , Neurônios/fisiologia , Transmissão Sináptica/fisiologia , Animais , Encéfalo/citologia , Encéfalo/fisiologia , Células Cultivadas , Feminino , Humanos , Sistemas Microeletromecânicos/instrumentação , Microeletrodos , Modelos Neurológicos , Rede Nervosa/citologia , Neurônios/citologia , Estimulação Luminosa/métodos , Ratos Sprague-DawleyRESUMO
Although microfluidic micro-electromechanical systems (MEMS) are well suited to investigate the effects of mechanical force on large populations of cells, their high-throughput capabilities cannot be fully leveraged without optimizing the experimental conditions of the fluid and particles flowing through them. Parameters such as flow velocity and particle size are known to affect the trajectories of particles in microfluidic systems and have been studied extensively, but the effects of temperature and buffer viscosity are not as well understood. In this paper, we explored the effects of these parameters on the timing of our own cell-impact device, the µHammer, by first tracking the velocity of polystyrene beads through the device and then visualizing the impact of these beads. Through these assays, we find that the timing of our device is sensitive to changes in the ratio of inertial forces to viscous forces that particles experience while traveling through the device. This sensitivity provides a set of parameters that can serve as a robust framework for optimizing device performance under various experimental conditions, without requiring extensive geometric redesigns. Using these tools, we were able to achieve an effective throughput over 360 beads/s with our device, demonstrating the potential of this framework to improve the consistency of microfluidic systems that rely on precise particle trajectories and timing.
Assuntos
Dispositivos Lab-On-A-Chip , Sistemas Microeletromecânicos/instrumentação , Soluções Tampão , Desenho de Equipamento , Microesferas , Tamanho da Partícula , Poliestirenos/química , Temperatura , ViscosidadeRESUMO
In this study, the authors demonstrate the fabrication, calibration, and testing of a piezoresistive microcantilever-based sensor for biomedical microelectromechanical system (BioMEMS) application. To use any sensor in BioMEMS application requires surface modification to capture the targeted biomolecules. The surface alteration comprises self-assembled monolayer (SAM) formation on gold (Au)/chromium (Cr) thin films. So, the Au/Cr coating is essential for most of the BioMEMS applications. The fabricated sensor uses the piezoresistive technique to capture the targeted biomolecules with the SAM/Au/Cr layer on top of the silicon dioxide layer. The stiffness (k) of the cantilever-based biosensor is a crucial design parameter for the low-pressure range and also influence the sensitivity of the microelectromechanical system-based sensor. Based on the calibration data, the average stiffness of the fabricated microcantilever with and without Au/Cr thin film is 141.39 and 70.53 mN/m, respectively, which is well below the maximum preferred range of stiffness for BioMEMS applications. The fabricated sensor is ultra-sensitive and selective towards Hg2+ ions in the presence of other heavy metal ions (HMIs) and good enough to achieve a lower limit of detection 0.75â ng/ml (3.73 pM/ml).
Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Sistemas Microeletromecânicos/instrumentação , Calibragem , Desenho de Equipamento , Ouro/química , Limite de Detecção , Mercúrio/análise , Mercúrio/química , Dióxido de Silício/química , Propriedades de Superfície , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/químicaRESUMO
INTRODUCTION: Heart failure (HF) leads to significant morbidity and mortality and imposes a large economic burden. Although there have been several advances in HF monitoring and management, HF-rehospitalization remains a significant problem. Remote monitoring of HF to detect early signs of decompensation has emerged in past years as an option to prevent or reduce the incidence of HF rehospitalization. The CardioMEMSTM HF system is a wireless pulmonary artery (PA) pressure monitoring system that detects changes in PA pressure and transmits data to the healthcare provider. Since changes in PA pressure happen early in the course of HF decompensation, the CardioMEMSTM system allows the provider to institute timely intensification of HF therapies to alter the course. In trial and registry data, the use of the CardioMEMSTM HF system has been associated with reduction in HF hospitalization, improvement in quality of life, symptoms, and physical activity. AREAS COVERED: This review will focus on the available data supporting its utilization in patients with HF. EXPERT OPINION: CardioMEMSTM is relatively safe and cost-effective, reduces heart failure hospitalization rates, and fits into intermediate to high-value medical care.
Assuntos
Monitorização Ambulatorial da Pressão Arterial/efeitos adversos , Insuficiência Cardíaca/terapia , Sistemas Microeletromecânicos/instrumentação , Monitorização Ambulatorial da Pressão Arterial/economia , Análise Custo-Benefício , Insuficiência Cardíaca/economia , Implante de Prótese de Valva Cardíaca/economia , Humanos , Artéria Pulmonar/cirurgiaRESUMO
Single-element transducer based ultrasound (US) imaging offers a compact and affordable solution for high-frequency preclinical and clinical imaging because of its low cost, low complexity, and high spatial resolution compared to array-based US imaging. To achieve B-mode imaging, conventional approaches adapt mechanical linear or sector scanning methods. However, due to its low scanning speed, mechanical linear scanning cannot achieve acceptable temporal resolution for real-time imaging, and the sector scanning method requires specialized low-load transducers that are small and lightweight. Here, we present a novel single-element US imaging system based on an acoustic mirror scanning method. Instead of physically moving the US transducer, the acoustic path is quickly steered by a water-proofed microelectromechanical (MEMS) scanner, achieving real-time imaging. Taking advantage of the low-cost and compact MEMS scanner, we implemented both a tabletop system for in vivo small animal imaging and a handheld system for in vivo human imaging. Notably, in combination with mechanical raster scanning, we could acquire the volumetric US images in live animals. This versatile US imaging system can be potentially used for various preclinical and clinical applications, including echocardiography, ophthalmic imaging, and ultrasound-guided catheterization.
Assuntos
Imageamento Tridimensional , Sistemas Microeletromecânicos/instrumentação , Ultrassonografia , Água , Animais , Feminino , Humanos , Camundongos Endogâmicos BALB C , Imagens de Fantasmas , Folhas de Planta/anatomia & histologiaRESUMO
Laser scanning based on Micro-Electro-Mechanical Systems (MEMS) scanners has become very attractive for biomedical endoscopic imaging, such as confocal microscopy or Optical Coherence Tomography (OCT). These scanners are required to be fast to achieve real-time image reconstruction while working at low actuation voltage to comply with medical standards. In this context, we report a 2-axis Micro-Electro-Mechanical Systems (MEMS) electrothermal micro-scannercapable of imaging large fields of view at high frame rates, e.g. from 10 to 80 frames per second. For this purpose, Lissajous scan parameters are chosen to provide the optimal image quality within the scanner capabilities and the sampling rate limit, resulting from the limited A-scan rate of typical swept-sources used for OCT. Images of 233 px × 203 px and 53 px × 53 px at 10 fps and 61 fps, respectively, are experimentally obtained and demonstrate the potential of this micro-scannerfor high definition and high frame rate endoscopic Lissajous imaging.
Assuntos
Sistemas Microeletromecânicos/métodos , Imagem Óptica/métodos , Sistemas Computacionais , Endoscópios , Endoscopia/métodos , Desenho de Equipamento , Humanos , Processamento de Imagem Assistida por Computador , Sistemas Microeletromecânicos/instrumentação , Sistemas Microeletromecânicos/estatística & dados numéricos , Microscopia Confocal/instrumentação , Microscopia Confocal/métodos , Microscopia Confocal/estatística & dados numéricos , Dispositivos Ópticos , Imagem Óptica/instrumentação , Imagem Óptica/estatística & dados numéricos , Fenômenos Ópticos , Tomografia de Coerência Óptica/instrumentação , Tomografia de Coerência Óptica/métodos , Tomografia de Coerência Óptica/estatística & dados numéricosRESUMO
Due to the large application of tapered beams in smart devices, such as scanning tunneling microscopes (STM), nano/micro electromechanical systems (NEMS/MEMS), atomic force microscopes (AFM), as well as in military aircraft applications, this study deals with the vibration behavior of laminated composite non-uniform nanobeams subjected to different boundary conditions. The micro-structural size-dependent free vibration response of composite laminated Euler-Bernoulli beams is here analyzed based on a modified couple stress elasticity, which accounts for the presence of a length scale parameter. The governing equations and boundary conditions of the problem are developed using the Hamilton's principle, and solved by means of the Rayleigh-Ritz method. The accuracy and stability of the proposed formulation is checked through a convergence and comparative study with respect to the available literature. A large parametric study is conducted to investigate the effect of the length-scale parameter, non-uniformity parameter, size dimension and boundary conditions on the natural frequencies of laminated composite tapered beams, as useful for design and optimization purposes of small-scale devices, due to their structural tailoring capabilities, damage tolerance, and their potential for creating reduction in weight.
Assuntos
Sistemas Microeletromecânicos/instrumentação , Elasticidade , Desenho de Equipamento , Modelos Teóricos , Tamanho da Partícula , Fenômenos Físicos , VibraçãoRESUMO
As pedestrian dead-reckoning (PDR), based on foot-mounted inertial sensors, suffers from accumulated error in velocity and heading, an improved heuristic drift elimination (iHDE) with a zero-velocity update (ZUPT) algorithm was proposed for simultaneously reducing the error in heading and velocity in complex paths, i.e., with pathways oriented at 45°, curved corridors, and wide areas. However, the iHDE algorithm does not consider the changes in pedestrian movement modes, and it can deteriorate when a pedestrian walks along a straight path without a pre-defined dominant direction. To solve these two problems, we propose enhanced heuristic drift elimination (eHDE) with an adaptive zero-velocity update (AZUPT) algorithm and novel heading correction algorithm. The relationships between the magnitude peaks of the y-axis angular rate and the detection thresholds were established only using the readings of the three-axis accelerometer and the three-axis gyroscopic, and a mechanism for constructing temporary dominant directions in real time was introduced. Real experiments were performed and the results showed that the proposed algorithm can improve the still-phase detection accuracy of a pedestrian at different movement motions and outperforms the iHDE algorithm in complex paths with many straight features.
Assuntos
Algoritmos , Navegação Espacial/fisiologia , Aceleração , Pé , Heurística , Humanos , Sistemas Microeletromecânicos/instrumentação , Sistemas Microeletromecânicos/métodos , Pedestres , Corrida , Caminhada , Dispositivos Eletrônicos VestíveisRESUMO
Micro-electro-mechanical system (MEMS) accelerometer-based inclinometers are widelyused to measure deformations of civil structures. To further improve the measurement accuracy, anew calibration technique was proposed in this paper. First, a single-parameter calibration modelwas constructed to obtain accurate angles. Then, an image-processing-based method was designedto obtain the key parameter for the calibration model. An ADXL355 accelerometer-basedinclinometer was calibrated to evaluate the feasibility of the technique. In this validationexperiment, the technique was proven to be reliable and robust. Finally, to evaluate theperformance of the technique, the calibrated MEMS inclinometer was used to measure thedeflections of a scale beam model. The experimental results demonstrate that the proposedtechnique can yield accurate deformation measurements for MEMS inclinometers. .
Assuntos
Acelerometria/instrumentação , Sistemas Microeletromecânicos/instrumentação , Automação , Calibragem , Processamento de Imagem Assistida por Computador , Reprodutibilidade dos Testes , IncertezaRESUMO
A linear piezoelectric micromachined ultrasound transducer (PMUT) array was fabricated and integrated into a device for photoacoustic imaging (PAI) of tissue phantoms. The PMUT contained 65 array elements, with each element having 60 diaphragms of [Formula: see text] diameter and [Formula: see text] pitch. A lead zirconate titanate (PZT) thin film was used as the piezoelectric layer. The in-air vibration response of the PMUT array elements showed a first mode resonance between 6 and 8 MHz. Hydrophone measurements showed 16.2 kPa average peak ultrasound pressure output at 7.5 mm from one element excited with 5 Vpp input. A receive sensitivity of ~0.48 mV/kPa was observed for a PMUT array element with 0 dB gain. The PMUT array was bonded to a custom-printed circuit board to enable compact integration with an optical fiber bundle for PAI. A broad photoacoustic bandwidth of ~89% was observed for the photoacoustic response captured from absorbing pencil lead targets. Linear scanning of a single element of a PMUT array was performed on different tissue phantoms embedded with light-absorbing targets to successfully demonstrate B-mode PAI using PMUTs.
Assuntos
Microtecnologia/instrumentação , Técnicas Fotoacústicas/instrumentação , Ultrassonografia/instrumentação , Desenho de Equipamento , Sistemas Microeletromecânicos/instrumentação , Imagens de Fantasmas , TransdutoresRESUMO
Piezoelectric materials, a type of "smart" material that generates electricity while deforming and vice versa, have been used extensively for many important implantable medical devices such as sensors, transducers, and actuators. However, commonly utilized piezoelectric materials are either toxic or nondegradable. Thus, implanted devices employing these materials raise a significant concern in terms of safety issues and often require an invasive removal surgery, which can damage directly interfaced tissues/organs. Here, we present a strategy for materials processing, device assembly, and electronic integration to 1) create biodegradable and biocompatible piezoelectric PLLA [poly(l-lactic acid)] nanofibers with a highly controllable, efficient, and stable piezoelectric performance, and 2) demonstrate device applications of this nanomaterial, including a highly sensitive biodegradable pressure sensor for monitoring vital physiological pressures and a biodegradable ultrasonic transducer for blood-brain barrier opening that can be used to facilitate the delivery of drugs into the brain. These significant applications, which have not been achieved so far by conventional piezoelectric materials and bulk piezoelectric PLLA, demonstrate the PLLA nanofibers as a powerful material platform that offers a profound impact on various medical fields including drug delivery, tissue engineering, and implanted medical devices.
Assuntos
Implantes Absorvíveis , Sistemas Microeletromecânicos/instrumentação , Nanofibras/química , Transdutores , Sistemas de Liberação de Medicamentos , Eletricidade , Eletrônica , Desenho de Equipamento , Monitorização Fisiológica/instrumentação , Pressão , Próteses e Implantes , Engenharia Tecidual , UltrassomRESUMO
In this paper, we introduce a novel type of transdermal drug delivery device (TD3) with a micro-electro-mechanical system (MEMS) design using computer-aided design (CAD) techniques as well as computational fluid dynamics (CFD) simulations regarding the fluid interaction inside the device during the actuation process. For the actuation principles of the chamber and microvalve, both thermopneumatic and piezoelectric principles are employed respectively, originating that the design perfectly integrates those principles through two different components, such as a micropump with integrated microvalves and a microneedle array. The TD3 has shown to be capable of delivering a volumetric flow of 2.92 × 10-5 cm3/s with a 6.6 Hz membrane stroke frequency. The device only needs 116 Pa to complete the suction process and 2560 Pa to complete the discharge process. A 38-microneedle array with 450 µm in length fulfills the function of permeating skin, allowing that the fluid reaches the desired destination and avoiding any possible pain during the insertion.
Assuntos
Sistemas de Liberação de Medicamentos/instrumentação , Desenho de Equipamento/instrumentação , Sistemas Microeletromecânicos/instrumentação , Administração Cutânea , Desenho Assistido por Computador/instrumentação , Humanos , Microinjeções/instrumentação , Agulhas , Preparações Farmacêuticas/administração & dosagem , Pele/efeitos dos fármacosRESUMO
The continuous measurements of vital signs (body temperature, blood pressure, pulse wave, and respiration rate) are important in many applications across various fields, including healthcare and sports. To realize such measurements, wearable devices that cause minimal discomfort to the wearers are highly desired. Accordingly, a device that can measure multiple vital signs simultaneously using a single sensing element is important in order to reduce the number of devices attached to the wearer's body, thereby reducing user discomfort. Thus, in this study, we propose a device with a microelectromechanical systems (MEMS)-based pressure sensor that can simultaneously measure the blood pulse wave and respiration rate using only one sensing element. In particular, in the proposed device, a thin silicone tube, whose inner pressure can be measured via a piezoresistive cantilever, is attached to the nose pad of a pair of eyeglasses. On wearing the eyeglasses, the tube of sensor device is in contact with the area above the angular artery and nasal cavity of the subject, and thus, both pulse wave and breath of the subject cause the tube's inner pressure to change. We experimentally show that it is possible to extract information related to pulse wave and respiration as the low-frequency and high-frequency components of the sensor signal, respectively.