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Publication: Oscillometric blood pressure measurements on smartphones using vibrometric force estimation

Authors: Colin Barry, Yinan Xuan, Ava Fascetti, Alison Moore, Edward J Wang Abstract This paper proposes a smartphone-based method for measuring Blood Pressure (BP) using the oscillometric method. For oscillometry, it is necessary to measure (1) the pressure applied to the artery and (2) the local blood volume change. This is accomplished by performing an oscillometric measurement at the finger's digital artery, whereby a user presses down on the phone's camera with steadily increasing force. The camera is used to capture the blood volume change using photoplethysmography. We devised a novel method for measuring the force applied of the finger without the use of specialized smartphone hardware with a technique called Vibrometric Force Estimation (VFE). The fundamental concept of VFE relies on a phenomenon where a vibrating object is dampened when an external force is…

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Publication: ACM 2024 Conference Proceeds – Development of a One Dollar Blood Pressure Monitor

Authors: Yinan Xuan, Ava J. Fascetti, Colin Barry, Edward J. Wang Abstract BPClip is an ultra-low-cost cuffless blood pressure monitor. As a universal smartphone attachment, BPClip leverages the computational imaging power of smartphones to perform oscillometry based blood pressure measurements. This paper examines different design considerations in BPClip's development. The cost and accuracy of blood pressure measurements are the central design goals. Both requirements are achieved with the initial prototype that achieves a 0.80 USD material cost and a mean absolute error of 8.72 and 5.49 mmHg for systolic and diastolic blood pressure, respectively. Since a main motivator to develop BPClip is making blood pressure monitoring more accessible, usability is also central to the design. User studies were conducted throughout the design process to inform the most intuitive and accessible design features. In this paper,…

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Publication: Data-driven discovery of movement-linked heterogeneity in neurodegenerative diseases. Nature Machine Intelligence

Authors: Mark Endo, Favour Nerrise, Qingyu Zhao, Edith V Sullivan, Li Fei-Fei, Victor W Henderson, Kilian M Pohl, Kathleen L Poston, Ehsan Adeli Abstract Neurodegenerative diseases manifest different motor and cognitive signs and symptoms that are highly heterogeneous. Parsing these heterogeneities may lead to an improved understanding of underlying disease mechanisms; however current methods are dependent on clinical assessments and somewhat arbitrary choice of behavioral tests. Herein, we present a data-driven subtyping approach using video-captured human motion and brain functional connectivity (FC) from resting-state (rs)-fMRI. We applied our framework to a cohort of individuals at different stages of Parkinson's disease (PD). The process mapped the data to low-dimensional measures by projecting them onto a canonical correlation space that identified three PD subtypes: Subtype I was characterized by motor difficulties and poor visuospatial abilities; Subtype II exhibited difficulties in non-motor…

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Publication: Development of a One Dollar Blood Pressure Monitor

Authors: Yinan Xuan, Ava J. Fascetti, Colin Barry, Edward J. Wang Abstract BPClip is an ultra-low-cost cuffless blood pressure monitor. As a universal smartphone attachment, BPClip leverages the computational imaging power of smartphones to perform oscillometry based blood pressure measurements. This paper examines different design considerations in BPClip's development. The cost and accuracy of blood pressure measurements are the central design goals. Both of these requirements are achieved with the initial prototype that achieves a $0.80 USD material cost and a mean absolute error of 8.72 and 5.49 mmHg for systolic and diastolic blood pressure, respectively. Since a main motivator to develop BPClip is making blood pressure monitoring more accessible, usability is also central to the design. User studies were conducted throughout the design process to inform the most intuitive and accessible design features. In…

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Publication: Capturing Measures That Matter: The Potential Value of Digital Measures of Physical Behavior for Alzheimer’s Disease Drug Development

Authors: Shelby L. Bachman, Jennifer M. Blankenship, Michael Busa, Corinna Serviente, Kate Lyden, and Ieuan Clay Abstract Alzheimer's disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia worldwide. Despite the magnitude of AD's impact on patients, caregivers, and society, nearly all AD clinical trials fail. A potential contributor to this high rate of failure is that established clinical outcome assessments fail to capture subtle clinical changes, entail high burden for patients and their caregivers, and ineffectively address the aspects of health deemed important by patients and their caregivers. AD progression is associated with widespread changes in physical behavior that have impacts on the ability to function independently, which is a meaningful aspect of health for patients with AD and important for diagnosis. However, established assessments of functional independence remain underutilized in…

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Publication: Ultra-low-cost mechanical smartphone attachment for no-calibration blood pressure measurement

Authors: Yinan Xuan, Colin Barry, Jessica De Souza, Jessica H Wen, Nick Antipa, Alison A Moore, Edward J Wang Abstract We propose an ultra-low-cost at-home blood pressure monitor that leverages a plastic clip with a spring-loaded mechanism to enable a smartphone with a flash LED and camera to measure blood pressure. Our system, called BPClip, is based on the scientific premise of measuring oscillometry at the fingertip to measure blood pressure. To enable a smartphone to measure the pressure applied to the digital artery, a moveable pinhole projection moves closer to the camera as the user presses down on the clip with increased force. As a user presses on the device with increased force, the spring-loaded mechanism compresses. The size of the pinhole thus encodes the pressure applied to the finger. In conjunction, the brightness…

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