Chest-Worn Inertial Sensors: A Survey of Applications and Methods

Abstract

Inertial Measurement Units (IMUs) are frequently implemented in wearable devices. Thanks to advances in signal processing and machine learning, applications of IMUs are not limited to those explicitly addressing body movements such as Activity Recognition (AR). On the other hand, wearing IMUs on the chest offers a few advantages over other body positions. AR and posture analysis, cardiopulmonary parameters estimation, voice and swallowing activity detection and other measurements can be approached through chest-worn inertial sensors. This survey tries to introduce the applications that come with the chest-worn IMUs and summarizes the existing methods, current challenges and future directions associated with them. In this regard, this paper references a total number of 57 relevant studies from the last 10 years and categorizes them into seven application areas. We discuss the inertial sensors used as well as their placement on the body and their associated validation methods based on the application categories. Our investigations show meaningful correlations among the studies within the same application categories. Then, we investigate the data processing architectures of the studies from the hardware point of view, indicating a lack of effort on handling the main processing through on-body units. Finally, we propose combining the discussed applications in a single platform, finding robust ways for artifact cancellation, and planning optimized sensing/processing architectures for them, to be taken more seriously in future research.

A multi-point heart rate monitoring using a soft wearable system based on fiber optic technology

“…To date, different methods have been proposed for HR monitoring from SCG signal and the accelerometers are still the most used 16 , 34 , 35 . The majority of works proposed single-sensor configuration typically placed on the torso at the level of the xyphoid process 13 .…”

“…The SCG was first observed by Bozhenko in 1961 14 , and its first application in clinical studies was in 1991, by Salerno and Zanetti 15 . Initially, this technique was abandoned by the scientific community mainly due to the accelerometers cumbersome size, but the advent of micro-electro-mechanical systems led to miniaturized inertial measurement units (IMUs), which integrate accelerometers and gyroscopes 16 . As a consequence, gyrocardiography (GCG) has also been proposed as a new non-invasive technique for assessing cardiac activity by using the angular velocities yielded by the gyroscope 17 .…”

Applications and Innovations on Sensor-Enabled Wearable Devices

“…The survey introduced in [ 7 ] deals with the applications that come with the chest-worn Inertial Measurements Units (IMUs), analyzes 57 relevant studies and summarizes the existing methods, current challenges and future directions associated with them. The authors categorizes the works into seven applications: Seismocardiography, Activity Analysis, Posture Analysis, Localization, Voice Analysis, Swallow Analysis, and Context Retrieval.…”

An Overview of Wearable Piezoresistive and Inertial Sensors for Respiration Rate Monitoring

“…The key body positions commonly monitored by the IMUs (Inertial Measurement Units) for detecting the respiration rate are the chest or abdomen since directly connected to the respiratory activity, along with other body signals like heartbeat, voice, swallowing and other movements [100,101]. Indeed, as demonstrated in [102], the best result for detecting body movements was obtained by placing IMUs on the chest and waist.…”