You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Ballistocardiography and Seismocardiography: A Review of Recent Advances 
Chapter Title:  D. Chair-Based BCG and SCG systems 
1. Abstract of Cited Paper (BIB001):  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.

Literature Review:
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.