Design and Modeling of a Plethysmographic Wearable Sensor for Heart Failure Non-Invasive Edema Monitoring

Heart Failure (HF) is a multifaceted syndrome characterized by the heart's inability to effectively pump oxygen- and nutrient-rich blood to meet the body's demands, making it a leading cause of hospitalization among individuals aged 65 and older. With a concerning mortality rate of 50% within the initial 5 years post-diagnosis, there is currently no universally accepted set of diagnostic criteria for HF. Recently, bioimpedance (BI) analysis has emerged as a promising technique for identifying a pivotal symptom: changes in body volume attributable to edema. This study proposes the development of a portable plethysmographic device to conduct real-time tests of leg volume changes in a cost-effective and non-invasive manner. The device looks to enhance at-home patient monitoring, for prompt diagnosis, and it is characterized by its compactness, wearability, wireless functionality, lightweight nature, and energy efficiency. It employs four electrodes for BI test, and data are transmitted via Bluetooth to an Android device for further analysis and monitoring.¹,

I. Introduction

Heart Failure (HF) poses a significant challenge impacting millions of individuals globally [1]–[4]. In terms of prevalence, one common manifestation in heart failure patients is edema, marked by swelling due to fluid accumulation in regions like the legs or feet [5], [6]. Existing methods for measuring such edemas often involve costly equipment [7], [8], cause discomfort for the patient, and are impractical for portable use. Consequently, there is a pressing need for the development of affordable and user-friendly sensors [8]. One potential resolution to this challenge could be the implementation of a plethysmographic sensor designed to monitor real-time changes in leg volume, as proposed in this context [8]–[10], [16]. Specifically, the aim is to introduce a personalized monitoring solution that seamlessly integrates advanced technology with precision medical care for edema assessment [9]–[12]. Employing the plethysmographic sensor for biomechanical data collection and a mobile app for analysis and tracking, this work prioritizes customization and adaptability [12]–[18].