Pressure Sensor Applications
As behind each medical procedure has a real science, complex medical devices for the diagnosis and treatment of secondary diseases of the airflow, and the silicon pressure sensor also exist behind a science. The three ways to use the airflow and silicon pressure sensor for medical applications is: anesthesia machines , sleep apnea machine, and hospital diagnostic equipment.
Anesthesia machine
Pharmacy for the equipment used in the anesthesia machine brings a unique set of challenges. These chemicals are usually viscosity accumulation may be generated within the device. In the manufacture of such equipment must take into account such factors, and take appropriate restorative measures. Medical equipment for patients is very important, so you want to choose a sensor offers excellent sensitivity and accuracy in the entire service life of the equipment. Select only able to meet the performance requirements, but also long-term stable performance of the sensor, we can ensure the normal use of the sensor during the entire life of the medical equipment. If you choose the right sensor, can achieve a 10-year sensor life cycle.
Engineers should consider the patient's respiratory rate. The range of patients including adults to health from poor health, slow respiratory rate, rapid breathing rate and lung capacity larger adults. Sensing portion need to be very sensitive, in order to correctly measure the patient's inspiratory and expiratory and anesthetic gas delivered to the air stream. Therefore, it will use two (or sometimes three) airflow sensor to measure the specific pneumatic subsystem. The designer should probably all important subsystem in the device to set a specific airflow sensor.
Plus anesthesia of Pharmacy and high humidity sensors together will result in harsh environment, so that the the expiratory circuit in the differential pressure sensor is superior airflow sensor. The adaptability of the gas medium pollution caused by the differential pressure sensor for moisture, anesthetic agents and other materials to be stronger. Should be used in the case of need to be high-pressure delivery source, or sensor requires direct contact with concentrated oxygen or anesthetic pharmaceutical sensor and dielectric isolation. In this case, stainless steel pressure sensor may be selected, and the dielectric isolation is the best, because it is more durable. If you should consider the need for a portable device, the airflow and the pressure sensor to use low power consumption, which can be reduced to the required size of the power supply and help limit on the total weight of the unit. Install the sensor at the manifold to the air flow channel, can help to reduce the design size and weight.
Another consideration is the output. Digital output, such as I2C and SPI protocols, so that the resolution of the sensor and the microprocessor integrated optimization of. Still exist on the analog output of the demand, the main reason is involved in some safety circuit rectifying demand does not allow software. The user might want to use original sensor output to trigger an alarm or security situation. It is very important to the ability of these two options provide both digital and analog. Finally, the response time of the sensor for the efficient delivery of narcotic pharmaceutical to a patient is essential. Use of current technology, anesthesia machine manufacturers to achieve a response time of 1ms.
Sleep apnea machine
Sleep apnea machine when it comes to the total error band, usually greater concern is the comfort and convenience of the patient, not demanding performance requirements. Since they are usually used in conjunction with the humidifier, so they need to be operated under conditions of high humidity and to maintain a stable performance. They must be durable, because they are usually the use of all kinds of people operating in the home environment. The requirements of the user of the device is mainly focused on the accuracy, stability, portability, and unit size / weight. Requirements on the noise is also very important, because this device is used during sleep. The need to use a lower pressure drop of the airflow sensor, because if the voltage drop is too high, the motor strength greater (pressure drop is equal to the impedance of the sensor), thereby increasing the noise and to shorten the life of the motor.
Therefore, the engineer should select able to sense the differential pressure or air flow sensor at a low rate. The sensor supplier should be able to measure the peak of the patient's breathing, or the turning point between the inspiratory and expiratory. For more complex sleep apnea machine, sometimes select airflow sensors instead of pressure sensors, because the ventilator needs to be more sensitive to the level of the low airflow. Once you determine the pressure, air flow, and the media needs in relation to consider the accuracy and stability of the demand, including total error band. Home sleep apnea machine must be durable, because external factors will affect unit performance.
For price reasons, usually select the enhanced digital products. With the purchase of the sensor has been enlarged compared to later add components to adjust the signal size will be more expensive. The same time, if you do this, then, for integration time will be shorter, which allows designers to more quickly realize the sensor, and the ultimate device to market faster. The design of the device according to the different types of sleep apnea, mechanical requirements (such as size, installation and research hole) may also bring some impact, because customers want to get smaller, elegant, and portable equipment. We may also need to consider the customer calibration function, especially of CPAP (continuous positive airway pressure) applications to maximize product performance, to best match the patient's breathing pattern.
Hospital diagnostic equipment
Hospital diagnostic equipment, including mass spectrometry, chromatography (eg, for gas, liquid and high performance liquid chromatography), laboratory automation systems and analyzers, such as for the use of blood, hematology, immunoassay and clinical chemistry analysis instrument. Key factors in the hospital diagnostic equipment selection sensor, high-resolution, high-precision and high stability are to focus consideration. The device needs to be able to detect even the smallest object quality. Thus, the diagnostic device generally has the highest resolution requirements, usually 16 or higher. Sensor accuracy and stability is very important to obtain accurate data and accurate data for the laboratory test results is essential, and is directly related to the life and safety of the patient.
Determine the need to detect the full range of pressure and flow and the increment is the primary factors to be considered. Application of the sensor in the field of hospital diagnosis may also require having the compatibility of the other medium with a clean, dry air outside. In some diagnostic equipment, the gases released from the plastic or adhesive, although the quantity is minimal, will contaminate the sample and the test results generated bias. Accuracy, especially for linearity and hysteresis error is concerned, are very important. Because of the sensitivity of the system as a whole, and the sensitivity of the sensor used is concerned, so it should try to reduce the hysteresis. 0.25% accuracy error is the best (non-linearity and hysteresis error), and 0.5% is usually allowed to exist maximum.
As described above, high resolution is critical, which is why the user of the diagnosis and analysis equipment may choose without amplified sensor to obtain as much as possible to the core / the raw sensor output, and to create a compensation and amplification algorithms reasons. Some sensor manufacturers through high-resolution A / D converter with amplified products. Note that the resolution A / D converter is not the resolution of the sensor manufacturer - the need to consider the resolution of the sensor itself. If the resolution of the sensor is lower, then the the extra digit A / D will only provide extra useless data.
Stability is very important, because the drift may unexpectedly affect the sensor reading. If the sensor device, the drift (calibration equipment prior to shipment), and the results will be deviations. Sensor in the process of manufacture and installation enabled, you must consider how to guard against the influence of the thermal and mechanical stresses, because this will affect the stability of the device performance. In hospital diagnostic applications, for the error associated with the drift and instability, 0.5% or lower is the maximum acceptable. And other medical applications is different, for the diagnostic equipment, the size is not a particularly critical factor, because most of them are bulky, inconvenient moving equipment, and is fixedly placed in the laboratory. Should first consider the resolution, accuracy and stability, followed by physical factors, such as output, dimensions, installation, and research hole and electricity demand.
Anesthesia machine
Pharmacy for the equipment used in the anesthesia machine brings a unique set of challenges. These chemicals are usually viscosity accumulation may be generated within the device. In the manufacture of such equipment must take into account such factors, and take appropriate restorative measures. Medical equipment for patients is very important, so you want to choose a sensor offers excellent sensitivity and accuracy in the entire service life of the equipment. Select only able to meet the performance requirements, but also long-term stable performance of the sensor, we can ensure the normal use of the sensor during the entire life of the medical equipment. If you choose the right sensor, can achieve a 10-year sensor life cycle.
Engineers should consider the patient's respiratory rate. The range of patients including adults to health from poor health, slow respiratory rate, rapid breathing rate and lung capacity larger adults. Sensing portion need to be very sensitive, in order to correctly measure the patient's inspiratory and expiratory and anesthetic gas delivered to the air stream. Therefore, it will use two (or sometimes three) airflow sensor to measure the specific pneumatic subsystem. The designer should probably all important subsystem in the device to set a specific airflow sensor.
Plus anesthesia of Pharmacy and high humidity sensors together will result in harsh environment, so that the the expiratory circuit in the differential pressure sensor is superior airflow sensor. The adaptability of the gas medium pollution caused by the differential pressure sensor for moisture, anesthetic agents and other materials to be stronger. Should be used in the case of need to be high-pressure delivery source, or sensor requires direct contact with concentrated oxygen or anesthetic pharmaceutical sensor and dielectric isolation. In this case, stainless steel pressure sensor may be selected, and the dielectric isolation is the best, because it is more durable. If you should consider the need for a portable device, the airflow and the pressure sensor to use low power consumption, which can be reduced to the required size of the power supply and help limit on the total weight of the unit. Install the sensor at the manifold to the air flow channel, can help to reduce the design size and weight.
Another consideration is the output. Digital output, such as I2C and SPI protocols, so that the resolution of the sensor and the microprocessor integrated optimization of. Still exist on the analog output of the demand, the main reason is involved in some safety circuit rectifying demand does not allow software. The user might want to use original sensor output to trigger an alarm or security situation. It is very important to the ability of these two options provide both digital and analog. Finally, the response time of the sensor for the efficient delivery of narcotic pharmaceutical to a patient is essential. Use of current technology, anesthesia machine manufacturers to achieve a response time of 1ms.
Sleep apnea machine
Sleep apnea machine when it comes to the total error band, usually greater concern is the comfort and convenience of the patient, not demanding performance requirements. Since they are usually used in conjunction with the humidifier, so they need to be operated under conditions of high humidity and to maintain a stable performance. They must be durable, because they are usually the use of all kinds of people operating in the home environment. The requirements of the user of the device is mainly focused on the accuracy, stability, portability, and unit size / weight. Requirements on the noise is also very important, because this device is used during sleep. The need to use a lower pressure drop of the airflow sensor, because if the voltage drop is too high, the motor strength greater (pressure drop is equal to the impedance of the sensor), thereby increasing the noise and to shorten the life of the motor.
Therefore, the engineer should select able to sense the differential pressure or air flow sensor at a low rate. The sensor supplier should be able to measure the peak of the patient's breathing, or the turning point between the inspiratory and expiratory. For more complex sleep apnea machine, sometimes select airflow sensors instead of pressure sensors, because the ventilator needs to be more sensitive to the level of the low airflow. Once you determine the pressure, air flow, and the media needs in relation to consider the accuracy and stability of the demand, including total error band. Home sleep apnea machine must be durable, because external factors will affect unit performance.
For price reasons, usually select the enhanced digital products. With the purchase of the sensor has been enlarged compared to later add components to adjust the signal size will be more expensive. The same time, if you do this, then, for integration time will be shorter, which allows designers to more quickly realize the sensor, and the ultimate device to market faster. The design of the device according to the different types of sleep apnea, mechanical requirements (such as size, installation and research hole) may also bring some impact, because customers want to get smaller, elegant, and portable equipment. We may also need to consider the customer calibration function, especially of CPAP (continuous positive airway pressure) applications to maximize product performance, to best match the patient's breathing pattern.
Hospital diagnostic equipment
Hospital diagnostic equipment, including mass spectrometry, chromatography (eg, for gas, liquid and high performance liquid chromatography), laboratory automation systems and analyzers, such as for the use of blood, hematology, immunoassay and clinical chemistry analysis instrument. Key factors in the hospital diagnostic equipment selection sensor, high-resolution, high-precision and high stability are to focus consideration. The device needs to be able to detect even the smallest object quality. Thus, the diagnostic device generally has the highest resolution requirements, usually 16 or higher. Sensor accuracy and stability is very important to obtain accurate data and accurate data for the laboratory test results is essential, and is directly related to the life and safety of the patient.
Determine the need to detect the full range of pressure and flow and the increment is the primary factors to be considered. Application of the sensor in the field of hospital diagnosis may also require having the compatibility of the other medium with a clean, dry air outside. In some diagnostic equipment, the gases released from the plastic or adhesive, although the quantity is minimal, will contaminate the sample and the test results generated bias. Accuracy, especially for linearity and hysteresis error is concerned, are very important. Because of the sensitivity of the system as a whole, and the sensitivity of the sensor used is concerned, so it should try to reduce the hysteresis. 0.25% accuracy error is the best (non-linearity and hysteresis error), and 0.5% is usually allowed to exist maximum.
As described above, high resolution is critical, which is why the user of the diagnosis and analysis equipment may choose without amplified sensor to obtain as much as possible to the core / the raw sensor output, and to create a compensation and amplification algorithms reasons. Some sensor manufacturers through high-resolution A / D converter with amplified products. Note that the resolution A / D converter is not the resolution of the sensor manufacturer - the need to consider the resolution of the sensor itself. If the resolution of the sensor is lower, then the the extra digit A / D will only provide extra useless data.
Stability is very important, because the drift may unexpectedly affect the sensor reading. If the sensor device, the drift (calibration equipment prior to shipment), and the results will be deviations. Sensor in the process of manufacture and installation enabled, you must consider how to guard against the influence of the thermal and mechanical stresses, because this will affect the stability of the device performance. In hospital diagnostic applications, for the error associated with the drift and instability, 0.5% or lower is the maximum acceptable. And other medical applications is different, for the diagnostic equipment, the size is not a particularly critical factor, because most of them are bulky, inconvenient moving equipment, and is fixedly placed in the laboratory. Should first consider the resolution, accuracy and stability, followed by physical factors, such as output, dimensions, installation, and research hole and electricity demand.
