A contact-free respiration monitor for smart bed and ambulatory monitoring applications

Abstract

The development of a contact-free respiration monitor has a broad range of clinical applications in the home and hospital setting. Current approaches suffer from a variety of problems including unreliability, low sensitivity, and high cost. This work describes a novel approach to contact-free respiration monitoring that addresses these shortcomings by employing a highly sensitive capacitance sensor to detect variations in capacitive coupling caused by breathing. A prototype system consisting of a synthetic-metallic pad, sensor electronics, and iPhone interface was built and its performance compared experimentally to the gold standard technique (Respiratory Inductance Plethysmography) on both a healthy volunteer and SimMan robotic mannequin. The prototype sensor effectively captured respiratory movements over breathing rates of 5-55 bpm; achieving an average spectral correlation of 0.88 (CI: 0.86-0.90) and 0.95 (CI: 0.95-0.96) to the gold standard using the SimMan and healthy volunteer respectively.

BreathSens: A Continuous On-Bed Respiratory Monitoring System With Torso Localization Using an Unobtrusive Pressure Sensing Array

“…However, the shape, type, or thickness of the mattress may introduce noise to the sensed data. Another type of indirect contact sensor is capacitance sensor, which measures the changes in electrical permittivity above the sensor caused by air in the lungs [13]. Again, it required the subject to be localized directly above the sensor.…”

News from the NIH: potential contributions of the behavioral and social sciences to the precision medicine initiative

“…Smartphones, now used by over 60 % of US adults, provide not only the computing platform for a range of apps but also internal sensors that can be used to capture physical movement, location, mode of transportation, sounds, images, social interactions, and some physiological parameters [22]. Smartphones also serve as an important conduit between wearable sensors such as accelerometers and heart rate monitors, and an emerging generation of specialized physiologic monitors for parameters such as blood glucose [23] and respiration [24]. Commerc i a l w e a r a b l e h e a l t h s e n s o r s , i n c l u d i n g smartwatches, are now owned by an increasingly larger proportion of the population [25], and research grade sensors to measure behavioral and environmental exposures have developed at a rapid pace since the initial efforts of the Genes, Environment, and Health Initiative [26].…”

Robust Ambient Multisensor Signal Fusion Towards Clinical Data Analytics

“…The optimal positioning for the desired physiological signal may also influence the sensing location. For instance, sensors may be placed near the expected chest and abdominal regions of the mattress for respiration analysis, or near the heart for cardiac measurement [26,28,30,[68][69][70]. Strategic placement is especially important for single sensors or arrays that cover only a small area.…”

“…Physiological signals have been captured by sensors in the environment in a variety of ways, but most ambient sensing modalities fall broadly into five main categories: pressure systems, Doppler systems, audiovisual systems, thermal systems, and textile electrodes. Pressure systems are generally placed where an individual would exert pressure when they lie, sit, or stand, and have included many modalities of sensors including pneumatic sensors [22,23,31,32,63,67], piezoelectric polymers [24,30,33,73,78,79], load cells [38,39,41,42,72], force sensitive resistors (FSR) [16][17][18]21,68,71], hydraulic sensors [24,66,80], capacitive sensors [14,69], indentation measurement potentiometers [65], electret films and foils [27,40], optical sensors [28,81], and strain gauges [82].…”

“…Spatial, temporal, and spectral methods of selection have been used. Sensor selection also encompasses systems where the selected sensor is predetermined and inputs from other sensors are ignored for the purposes of cardiopulmonary monitoring (although they may be used for other purposes), as in [69], [66], and [80].…”