Circuitry Assessment

The sensor can either be mounted in a DIE28 package (dual-inline package with 28 pins) for testing and calibration purposes or in a TO-package (Fig. 6.15), which is 

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The following chapter includes the description of different types of microhotplates that feature resistor and transistor heating elements. Three of them were specifically designed to be monolithically integrated with circuitry, and one was a testing device that was used for the assessment of temperature distributions on the microhotplates. 

For thermal characterization and temperature sensor calibration a microhotplate was fabricated, which is identical to that on the monoHthic sensor chips, but does not include any electronics. The functional elements of this microhotplate are connected to bonding pads and not wired up to any circuitry, so that the direct access to the hotplate components without electronics interference is ensured. The assessment of characteristic microhotplate properties, such as the thermal resistance of the microhotplate and its thermal time constant, were carried out with these discrete microhotplates. 

The limit for the operating temperature of CMOS-microhotplates can be extended by using the microhotplate that was presented in Sect. 4.3. We now detail high-temperature microhotplates with Pt-resistors that have been realized as a single-chip device with integrated circuitry. While the aluminum-based devices presented in Sect. 4.1 were limited to 350 °C, these improved microhotplates can be heated to temperatures up to 500 °C. As the typical resistance value of the Pt-resistor is between 50 and 100 Q, a chip architecture adapted to the low temperature sensor resistance was developed. The system performance was assessed, and chemical measurements have been performed that demonstrate the full functionality of the chip. 

In the passive patient, intrinsic PEEP can be assessed in two ways. First, when an inadequate expiratory time is producing intrinsic PEEP, analysis of the flow graphic will show that expiratory flow has not returned to zero before the next breath is given. Second, intrinsic PEEP in alveolar units that have patent airways can be quantified during a prolonged expiratory hold maneuver that permits equilibration of the intrinsic PEEP throughout the ventilator circuitry (10). 

Peak pressure is the highest pressure level reached by the sound wave, and assessments of this will be needed where there is exposure to impact or explosive noise. A meter capable of carrying out the measurement must be specially selected, because of the damping event of needle-based measuring which will consistently produce under-reading. A similar effect can be found in standard electronic circuitry. 

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