Ballistocardiography and Seismocardiography: A Review of Recent Advances <s> D. Chair-Based BCG and SCG systems <s> Ballistocardiography is a non-invasive technique for the assessment of cardiac function. We built a measurement setup to measure the ballistocardiogram from a normal chair using EMFi sensors. The ballistocardiogram is recorded from a subject sitting on the chair. The measured signal is amplified by a specially-designed charge amplifier and digitized by a circulation monitor. A PC provides a user interface for the measurement devices, records the data and displays the results. Impedance cardiography and ECG serve as reference measurements for the ballistocardiography. To test the system, one healthy 24-year-old male and one healthy 22-year-old female were measured. It is concluded that the ballistocardiogram waveforms described in the literature can be recognized from the EMFi signal measured from a normal chair. <s> BIB001 </s> Ballistocardiography and Seismocardiography: A Review of Recent Advances <s> D. Chair-Based BCG and SCG systems <s> Embedded wireless sensors are important components of mobile distributed computing networks, and one of the target applications areas is health care. The preservation of mobility for senior citizens is one of the key issues in maintaining an independent lifestyle. Thus health technologies inside a car can contribute both to safety issues (supervision of driver fitness) as well as healthcare issues by monitoring vitals signs imperceptibly. In this paper, three embedded measurement techniques for non-contact monitoring of vital signals have been investigated. Specifically, capacitive electrocardiogram (cECG) monitoring, mechanical movement analysis (ballistocardiogram, BCG) using piezo-foils and inductive impedance monitoring were examined regarding their potential for integration into car seats. All three sensing techniques omit the need for electroconductive contact to the human body, but require defined mechanical boundary conditions (stable distances or, in the case of BCG, frictional connection). The physical principles of operation, the specific boundary conditions regarding automotive integration and the results during wireless operation in a running car are presented. All three sensors were equipped with local intelligence by incorporating a microcontroller. To eliminate the need for additional cabling, a wireless Bluetooth communication module was added and used to transmit data to a measurement PC. Finally, preliminary results obtained during test drives on German city roads and highways are discussed. <s> BIB002
Chair-based systems have mainly used EMFi sensors based on piezoelectric transduction. Koivistoinen et al. attached EMFi sensors to a chair to measure BCG signals from two seated subjects, and found the signal shape to be similar to other BCG measurements from the literature BIB001 . Walter et al. placed an EMFi mat in the cushion of the driver's seat in a car to measure the BCG for automatically monitoring driver fitness BIB002 . These systems provide a means for measuring BCG or SCG signals from patients who cannot stand still on their own, minimize motion artifacts, and allow the user to be comfortable during the measurement. The main disadvantages for chair-based BCG recording are the reduction of signal amplitude compared to measurements using table, bed, or weighing scale systems, and the effects of postural changes on signal quality.