An implantable capacitive pressure sensor for biomedical applications (original) (raw)
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Designing and fabricating micro-pressure sensors for spiral cuff electrode
Ab~fluct-Cuff electrode an important component of neural prostheseq has been developed and improved in many research groups It is well known that cuff electrode has the potential hazard of causing nerve in& by compression. The goal of this study is to design a spiral cuff electrode witkmbedded micr &pressure sensor by using g i c r 0-glectr @mechanical system (MEMS) technologies. The pressure sensor4 serving as an on-line well-being monitor,can prevent Lcbemic necrosis of a nerve from excessive pressure We adopted capacitive mechanism as the basic configuration, because of its high sensitivity and good noise resistance. Tbesensor was designed and simulated witlfkite element analyses.
Design, Manufacture and Testing of Capacitive Pressure Sensors for Low-Pressure Measurement Ranges
Micromachines
This article presents the design, manufacture and testing of a capacitive pressure sensor with a high, tunable performance to low compressive loads (<10 kPa) and a resolution of less than 0.5 kPa. Such a performance is required for the monitoring of treatment efficacy delivered by compression garments to treat or prevent medical conditions such as deep vein thrombosis, leg ulcers, varicose veins or hypertrophic scars. Current commercial sensors used in such medical applications have been found to be either impractical, costly or of insufficient resolution. A microstructured elastomer film of a polydimethylsiloxane (PDMS) blend with a tunable Young's modulus was used as the force-sensing dielectric medium. The resulting 18 mm × 18 mm parallel-plate capacitive pressure sensor was characterised in the range of 0.8 to 6.5 kPa. The microstructuring of the surface morphology of the elastomer film combined with the tuning of the Young's modulus of the PDMS blend is demonstrated to enhance the sensor performance achieving a 0.25 kPa pressure resolution and a 10 pF capacitive change under 6.5 kPa compressive load. The resulting sensor holds good potential for the targeted medical application.
An Interdigital Capacitive Electrode Modified as a Pressure Sensor
Inter-digital capacitive electrodes working as electric field sensors have been developed for touch panel applications. Evaluation circuits to convert variations in electric fields in such sensors into computer compatible data are commercially available. We report development of an Interdigital capacitive electrode working as a sensitive pressure sensor in the range 0-120 kPa. Essentially it is a touch/proximity sensor converted into a pressure sensor with a suitable elastomer buffer medium acting as the pressure transmitter. The performance of the sensor has been evaluated and reported. Such sensors can be made very economical in comparison to existing pressure sensors. Moreover, they are very convenient to be fabricated into sensor arrays involving a number of sensors for distributed pressure sensing applications such as in biomedical systems. Copyright © 2008 IFSA.
Optimization of Nano Capacitive Pressure Sensor for Medical Applications
IOP Conference Series: Materials Science and Engineering, 2021
Nano/NEMS sensors have emerged from MEMS technology. Nano sensors have got lot of applications in medical and health care applications. Nano sensors have lot of attributes which make them very unique and special, such as: small size, low mass, high sensitivity and low cost of production. In this paper we present optimization of nano capacitive pressure sensor dimensions for medical applications. Capacitive pressure sensors are well suited for low pressure sensing applications. Typically, in medical field involve low pressure levels ranging from few Pascals to kilo Pascals. DoE is used for the optimization of sensor dimensions. The sensor is optimized to operate over the pressure range up to 100 kPa. Over this pressure range the sensor dimensions are optimized to get better response in terms of capacitance. The proposed optimization illustrates the dimensions best suited for the design of nano capacitive pressure sensor for operational range up to 100 kPa.
Development of Biocompatible MEMS Wireless Capacitive Pressure Sensor
Journal of Microelectronics and Electronic Packaging, 2005
The objective of this research was to develop a wireless pressure sensor useful for monitoring bladder pressure. The wireless sensor consists of an active capacitive element and an inductor coil. The changes in pressure are related to the changes in the resonant frequency of the internal sensor. The existing pressure sensors have inductors formed on both sides of the substrate. The changes in internal capacitance of these sensors are related to the changes in pressure by impedance matching of the internal LC circuit. The deviation in bladder pressure is an important variable in evaluating the diseased state of the bladder. The inductor designed for this application is a spirally wound inductor fabricated adjacent to the capacitor. The external sensing uses equivalent changes in internal LC. The resonant frequency of the internal sensor is defined by the deformation of the plate, causing the plate to touch the dielectric on the fixed capacitive plate, which is reflected as changes in...
Development of a micromachined pressure transducer for biomedical device/tissue interfaces
In many medical situations, the need for measuring the pressure applied to a tissue quickly and accurately is crucial. Most conventional devices do not measure the actual pressure applied to the tissue because they do not compensate for the tissue or device compliance characteristics and need to be calibrated for each measurement environment. Neuromuscular damage may occur if too much pressure is applied to a tissue for an extended period of time in applications such as tourniquet systems. Incorrect diagnosis may occur if too little pressure is applied in applications such as mammography units. A compliance-independent pressure transducer has other biomedical applications in surgical retraction devices and prosthetic sockets. To eliminate the compliance problem, a pressure transducer was developed using bulk micromachining technology
A micro-capacitive pressure sensor design and modelling
Journal of Sensors and Sensor Systems, 2016
Measuring air pressure using a capacitive pressure sensor is a robust and precise technique. In addition, a system that employs such transducers lies within the low power consumption applications such as wireless sensor nodes. In this article a high sensitivity with an elliptical diaphragm capacitive pressure sensor is proposed. This design was compared with a circular diaphragm in terms of thermal stresses and pressure and temperature sensitivity. The proposed sensor is targeted for tyre pressure monitoring system application. Altering the overlapping area between the capacitor plates by decreasing the effective capacitance area to improve the overall sensitivity of the sensor (C/C), temperature sensitivity, and built-up stresses is also examined in this article. Theoretical analysis and finite element analysis (FEA) were employed to study pressure and temperature effects on the behaviour of the proposed capacitive pressure sensor. A MEMS (micro electro-mechanical systems) manufacturing processing plan for the proposed capacitive sensor is presented. An extra-low power short-range wireless read-out circuit suited for energy harvesting purposes is presented in this article. The developed read-out circuitry was tested in terms of sensitivity and transmission range.
Micromachined capacitive pressure sensor with signal conditioning electronics
2010
Micromachined capacitive pressure sensors for harsh environment together with interfacing electronic circuits have been studied in this project. Micro-electromechanical systems (MEMS) have been proposed as substitutes for macro scale sensor’s systems in many different fields and are the only possible solution in many cases where, for example, the dimensions of the sensing element is the limiting factor. Furthermore, MEMS can significantly reduce costs and power consumption being the best candidate for consumer electronics such as mobile phones and cameras, or for the automotive industry where a great deal of sensors are used. Pressure sensors are among the most successful MEMS and are used in a huge variety of applications. In this project an absolute capacitive pressure sensor has been developed with the aim to integrate it in pump control systems to improve the efficiency of the pump. The developed MEMS consist of hermetically sealed vacuum cavities surrounded by two heavily doped...
Measurement of external pressures generated by nerve cuff electrodes
IEEE Transactions on Rehabilitation Engineering, 2000
When external pressures are applied to a peripheral nerve, tissue damage can occur via compression and blood flow occlusion, resulting in degeneration and demyelination of axons. Although many types of nerve electrodes have been designed to avoid or minimize this pressure during stimulation of the nerve or recording of its activity, the measurement of the pressure exerted by these cuffs has not been reported. Currently, only theoretical models are used to predict nerve cuff electrode pressures. We have developed a nerve cuff electrode pressure sensor to measure external pressures exerted by peripheral nerve cuff electrodes. The sensor has a high sensitivity, linear response with little hysteresis and reproducible output. Pressure measurements have been obtained for split-ring and spiral cuff electrodes. The measurements obtained are in agreement with theoretical predictions. Moreover, they indicate that the pressures exerted by cuffs currently used for stimulation generate only a small amount of pressure, which is below the pressure required to occlude blood flow in nerves. The results also suggest that this new sensor can provide reliable measurement of external pressures exerted by nerve electrodes and would be an important tool for comparing various nerve cuff electrode designs.
Molecules
Sensitive and flexible pressure sensors have invoked considerable interest for a broad range of applications in tactile sensing, physiological sensing, and flexible electronics. The barrier between high sensitivity and low fabrication cost needs to be addressed to commercialize such flexible pressure sensors. A low-cost sacrificial template-assisted method for the capacitive sensor has been reported herein, utilizing a porous Polydimethylsiloxane (PDMS) polymer and a multiwalled carbon nanotube (MWCNT) composite-based dielectric layer. The sensor shows high sensitivity of 2.42 kPa−1 along with a low limit of detection of 1.46 Pa. The high sensitivity originates from adding MWCNT to PDMS, increasing the composite polymer’s dielectric constant. Besides this, the pressure sensor shows excellent stability at a cyclic loading of 9000 cycles, proving its reliability for long-lasting application in tactile and physiological sensing. The high sensitivity of the sensor is suitable for the de...