Respiratory sensors

Figure 10.5 SmartLife has developed softsensor systems aimed for the improvement of lifestyle. The HealthVest is created with integrally knitted ECG electrodes, respiratory sensors, and conductive pathways.

Most respiratory sensors are based on the pneumography and measure the changes of chest or abdomen circumference. As the circumference increases or decreases, the electrical property of the textile sensor changes, and this change could be interpreted into inhalation and exhalation activities of the wearer. The most common methods include respiratory inductive plethysmography (RIP), piezoresistive sensors, and piezoelectric sensors (Merritt et al., 2009). 

Detection of Bromine Vapor. Bromine vapor in air can be monitored by using an oxidant monitor instmment that sounds an alarm when a certain level is reached. An oxidant monitor operates on an amperometric principle. The bromine oxidizes potassium iodide in solution, producing an electrical output by depolarizing one sensor electrode. Detector tubes, usefiil for determining the level of respiratory protection required, contain (9-toluidine that produces a yellow-orange stain when reacted with bromine. These tubes and sample pumps are available through safety supply companies (54). The usefiil concentration range is 0.2—30 ppm. 

Instrumentation is also fitted to provide a continuous display of important variables such as temperature and pH, the power used hy the electric motor, airflow, dissolved oxygen and exhaust gas analysis. Manual or computer feedback control can be based either directly on the signals provided hy the prohes and sensors or on derived data calculated from those signals, such as the respiratory coefficient or the rate of change of pH. Mass spectronomical analysis of exhaust gases can provide valuable physiological information. 

Reliable measurements of L-lactate are of great interest in clinical chemistry, the dairy and vine industry, biotechnology, or sport medicine. In particular, blood lactate levels are indicative of various pathological states, including shock, respiratory insufficiencies, and heart and liver diseases. Silica sol-gel encapsulation of the lactate dehydrogenase and its cofactor was employed as a disposable sensor for L-lactate51. The sensor utilized the changes in absorbance or fluorescence from reduced cofactor nicotinamide adenine dinucleotide (NADH) upon exposure to L-lactate. 

The bulk of the curve appears identical to the normal curve. However, during the plateau phase, a large cleft is seen as the patient makes a transient respiratory effort and draws fresh gas over the sensor. 

Usually seen when the respiratory rate is slow. The curve starts as normal but the expiratory pause is prolonged owing to the slow rate. Fresh gas within the circuit is able to pass over the sensor causing the Pco2 to fall. During this time, the mechanical pulsations induced by the heart force small quantities of alveolar gas out of the lungs and over the sensor, causing transient spikes. Inspiration in the above example does not occur until point A. 

Microbial Sensors on a Respiratory Basis for Wastewater Monitoring... 

Fig. 2. Physiological responses of a respiratory-based microbial sensor...

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