Instrumentation & Measurement Magazine 24-2 - 57

the carotid artery [12]. PWV is inversely proportional to the
pulse arrival time which represents the time delay between
ECG R-peak and the foot of the distal arterial waveform obtained from the ultrasound sensor.
There has also been a surge of wearable devices with novel
tonometric sensors for measurement and recording of the arterial pressure waveform in recent years. A multi-array seven
channel 17 mm x 17 mm pressure sensor was developed to be
placed over the radial artery [13]. Capacitive and piezoresistive MEMS pressure sensors have been developed by major
manufacturers including Analog Device, STMicroelectronics,
Murata, and others. A MEMS pressure sensor element with
three sensors for the radial artery was also recently developed
[14]. Both technologies described in [13] and [14] captured a
high-quality arterial pulse wave.
Recently, there have been significant improvements in PPG
sensor technology. Large numbers of integrated single-chip solutions for photoplethysmography, pulse oximetry, and ECG
are available from major manufacturers including Texas Instruments, Maxim Integrated, AMS, Osram Opto Semiconductors,
and others. Some of these solutions only require light emitting
diodes (LEDs) and ECG electrodes to be added externally. New
research on PPG sensors includes ultrathin, soft, skin-like electronic patch devices [15] as well as devices with a large number of
LEDs and photodiodes (up to 16) placed in different orientations.

Modeling, Simulation, and Databases
Computational (in silico) modeling is the direct use of computer simulation and modeling in biomedical research with
the goal of simulating biological processes. Computational
modeling of arteries and application of the models to estimating arterial stiffness is becoming increasingly popular.
Computational modeling is important as it allows for:
◗◗ evaluating the influence of individual cardiovascular
properties and their variations over time on the arterial
pulse wave and consequently on the arterial stiffness,
◗◗ evaluating the arterial pulse wave at different points of
interest,
◗◗ analyzing the effect of aging and different cardiovascular
diseases on the arterial pulse and arterial stiffness,
◗◗ providing exact measurement references which might be
difficult to obtain from in vivo studies,
◗◗ developing methods for estimating uncertainty of
measurements,
◗◗ generating arterial pulses of virtual patients, and
◗◗ patient-specific modeling and potentially developing a
digital twin.
Major disadvantages of this approach include reliance on
modeling hypothesis and setting different parameters in the
models where some parameters might be unknown or based
on previous studies that might not be completely relevant.
Nevertheless, computational modeling can provide additional
understanding of the physiological processes of the arterial
system.
Three types of computational models are commonly applied as low‑dimensional physics‑based models of systemic
April 2021	

arteries: Windkessel model, one-dimensional (1-D) models,
and tube-load models [16]. Windkessel models present the
pulse as a function of time only and is a function of equivalent
inductance, compliance and resistance. On the other hand, 1-D
models and tube-load models can also represent distributed
properties of the arterial system. The 1-D model is based on
the Navier-Stokes equation, and it is used to simulate pressure
and flow at any position in the entire arterial tree. Tube-load
models are transmission line models, which are made up of
multiple parallel tubes with loads representing arteries, and as
such they can represent wave propagation and reflection with
only a few parameters [16]. Multiple models connected commonly in series can represent multiple arteries.
Modeling and simulation of arterial blood pressure, blood
flow velocity, volume flow rate, and PPG pulse wave at a common measurement site was described recently in [17]. The
research resulted in a database of pulses of more than 4,000
virtual patients. MATLAB (The MathWorks Inc., Natick, MA)
code is provided, and it allows for generating new virtual
patients with varying parameters. Arterial stiffness was estimated based on PPG-derived indices, and correlation between
the indices and PWV is reported.
A database of simulated arterial waves of 3,325 virtual
subjects, each with distinctive arterial pulse waveforms is described in [18]. The following parameters are varied between
subjects: arterial PWV, diameter of arteries, heart rate, stroke
volume and peripheral vascular resistance. It is applied for
foot-to-foot PWV simulation and estimating arterial stiffness.
A 1-D model of the arterial hemodynamics is used in both [17]
and [18], but the model presented in [17] is based on a larger
number of parameters.
Besides datasets of virtual patients, there exist several patient databases. A large dataset of police officers was collected
in Great Britain from 4,378 subjects and contains, among many
other parameters, finger PPG pulse waveforms alongside brachial-femoral pulse wave velocities (bfPWV) and therefore can
be used for research related to arterial stiffness [19]. Although
this database is not available online, data can be acquired after obtaining the approval from the data access committee and
the Ethics committee.
Another large dataset on atherosclerosis, which is an important sub-type of arterial hardening and narrowing caused
by plaque build-up, is available to researchers through the
Multi-Ethnic Study of Atherosclerosis (MESA) [20]. This dataset includes several biological, behavioral, and environmental
markers obtained from over 6800 men and women living in
different communities in the U.S.
Smaller public datasets also exist such as " Smart Health for
Assessing the Risk of Events via ECG " which is available online through the Physionet website. This dataset includes 89
subjects suffering from carotid artery disease and 37 healthy
subjects.

Physical and Machine Learning Models
In this section, we describe approaches that are based on a
single point measurement (such as PPG measurement) or

IEEE Instrumentation & Measurement Magazine	57



Instrumentation & Measurement Magazine 24-2

Table of Contents for the Digital Edition of Instrumentation & Measurement Magazine 24-2

No label
Instrumentation & Measurement Magazine 24-2 - No label
Instrumentation & Measurement Magazine 24-2 - Cover2
Instrumentation & Measurement Magazine 24-2 - 1
Instrumentation & Measurement Magazine 24-2 - 2
Instrumentation & Measurement Magazine 24-2 - 3
Instrumentation & Measurement Magazine 24-2 - 4
Instrumentation & Measurement Magazine 24-2 - 5
Instrumentation & Measurement Magazine 24-2 - 6
Instrumentation & Measurement Magazine 24-2 - 7
Instrumentation & Measurement Magazine 24-2 - 8
Instrumentation & Measurement Magazine 24-2 - 9
Instrumentation & Measurement Magazine 24-2 - 10
Instrumentation & Measurement Magazine 24-2 - 11
Instrumentation & Measurement Magazine 24-2 - 12
Instrumentation & Measurement Magazine 24-2 - 13
Instrumentation & Measurement Magazine 24-2 - 14
Instrumentation & Measurement Magazine 24-2 - 15
Instrumentation & Measurement Magazine 24-2 - 16
Instrumentation & Measurement Magazine 24-2 - 17
Instrumentation & Measurement Magazine 24-2 - 18
Instrumentation & Measurement Magazine 24-2 - 19
Instrumentation & Measurement Magazine 24-2 - 20
Instrumentation & Measurement Magazine 24-2 - 21
Instrumentation & Measurement Magazine 24-2 - 22
Instrumentation & Measurement Magazine 24-2 - 23
Instrumentation & Measurement Magazine 24-2 - 24
Instrumentation & Measurement Magazine 24-2 - 25
Instrumentation & Measurement Magazine 24-2 - 26
Instrumentation & Measurement Magazine 24-2 - 27
Instrumentation & Measurement Magazine 24-2 - 28
Instrumentation & Measurement Magazine 24-2 - 29
Instrumentation & Measurement Magazine 24-2 - 30
Instrumentation & Measurement Magazine 24-2 - 31
Instrumentation & Measurement Magazine 24-2 - 32
Instrumentation & Measurement Magazine 24-2 - 33
Instrumentation & Measurement Magazine 24-2 - 34
Instrumentation & Measurement Magazine 24-2 - 35
Instrumentation & Measurement Magazine 24-2 - 36
Instrumentation & Measurement Magazine 24-2 - 37
Instrumentation & Measurement Magazine 24-2 - 38
Instrumentation & Measurement Magazine 24-2 - 39
Instrumentation & Measurement Magazine 24-2 - 40
Instrumentation & Measurement Magazine 24-2 - 41
Instrumentation & Measurement Magazine 24-2 - 42
Instrumentation & Measurement Magazine 24-2 - 43
Instrumentation & Measurement Magazine 24-2 - 44
Instrumentation & Measurement Magazine 24-2 - 45
Instrumentation & Measurement Magazine 24-2 - 46
Instrumentation & Measurement Magazine 24-2 - 47
Instrumentation & Measurement Magazine 24-2 - 48
Instrumentation & Measurement Magazine 24-2 - 49
Instrumentation & Measurement Magazine 24-2 - 50
Instrumentation & Measurement Magazine 24-2 - 51
Instrumentation & Measurement Magazine 24-2 - 52
Instrumentation & Measurement Magazine 24-2 - 53
Instrumentation & Measurement Magazine 24-2 - 54
Instrumentation & Measurement Magazine 24-2 - 55
Instrumentation & Measurement Magazine 24-2 - 56
Instrumentation & Measurement Magazine 24-2 - 57
Instrumentation & Measurement Magazine 24-2 - 58
Instrumentation & Measurement Magazine 24-2 - 59
Instrumentation & Measurement Magazine 24-2 - 60
Instrumentation & Measurement Magazine 24-2 - 61
Instrumentation & Measurement Magazine 24-2 - 62
Instrumentation & Measurement Magazine 24-2 - 63
Instrumentation & Measurement Magazine 24-2 - 64
Instrumentation & Measurement Magazine 24-2 - 65
Instrumentation & Measurement Magazine 24-2 - 66
Instrumentation & Measurement Magazine 24-2 - 67
Instrumentation & Measurement Magazine 24-2 - 68
Instrumentation & Measurement Magazine 24-2 - 69
Instrumentation & Measurement Magazine 24-2 - 70
Instrumentation & Measurement Magazine 24-2 - 71
Instrumentation & Measurement Magazine 24-2 - 72
Instrumentation & Measurement Magazine 24-2 - 73
Instrumentation & Measurement Magazine 24-2 - 74
Instrumentation & Measurement Magazine 24-2 - 75
Instrumentation & Measurement Magazine 24-2 - 76
Instrumentation & Measurement Magazine 24-2 - 77
Instrumentation & Measurement Magazine 24-2 - 78
Instrumentation & Measurement Magazine 24-2 - 79
Instrumentation & Measurement Magazine 24-2 - 80
Instrumentation & Measurement Magazine 24-2 - 81
Instrumentation & Measurement Magazine 24-2 - 82
Instrumentation & Measurement Magazine 24-2 - 83
Instrumentation & Measurement Magazine 24-2 - 84
Instrumentation & Measurement Magazine 24-2 - 85
Instrumentation & Measurement Magazine 24-2 - 86
Instrumentation & Measurement Magazine 24-2 - 87
Instrumentation & Measurement Magazine 24-2 - 88
Instrumentation & Measurement Magazine 24-2 - 89
Instrumentation & Measurement Magazine 24-2 - 90
Instrumentation & Measurement Magazine 24-2 - 91
Instrumentation & Measurement Magazine 24-2 - 92
Instrumentation & Measurement Magazine 24-2 - 93
Instrumentation & Measurement Magazine 24-2 - 94
Instrumentation & Measurement Magazine 24-2 - 95
Instrumentation & Measurement Magazine 24-2 - 96
Instrumentation & Measurement Magazine 24-2 - 97
Instrumentation & Measurement Magazine 24-2 - 98
Instrumentation & Measurement Magazine 24-2 - 99
Instrumentation & Measurement Magazine 24-2 - 100
Instrumentation & Measurement Magazine 24-2 - 101
Instrumentation & Measurement Magazine 24-2 - 102
Instrumentation & Measurement Magazine 24-2 - 103
Instrumentation & Measurement Magazine 24-2 - 104
Instrumentation & Measurement Magazine 24-2 - 105
Instrumentation & Measurement Magazine 24-2 - 106
Instrumentation & Measurement Magazine 24-2 - 107
Instrumentation & Measurement Magazine 24-2 - 108
Instrumentation & Measurement Magazine 24-2 - 109
Instrumentation & Measurement Magazine 24-2 - 110
Instrumentation & Measurement Magazine 24-2 - 111
Instrumentation & Measurement Magazine 24-2 - 112
Instrumentation & Measurement Magazine 24-2 - 113
Instrumentation & Measurement Magazine 24-2 - 114
Instrumentation & Measurement Magazine 24-2 - 115
Instrumentation & Measurement Magazine 24-2 - 116
Instrumentation & Measurement Magazine 24-2 - 117
Instrumentation & Measurement Magazine 24-2 - 118
Instrumentation & Measurement Magazine 24-2 - 119
Instrumentation & Measurement Magazine 24-2 - 120
Instrumentation & Measurement Magazine 24-2 - 121
Instrumentation & Measurement Magazine 24-2 - 122
Instrumentation & Measurement Magazine 24-2 - 123
Instrumentation & Measurement Magazine 24-2 - 124
Instrumentation & Measurement Magazine 24-2 - 125
Instrumentation & Measurement Magazine 24-2 - 126
Instrumentation & Measurement Magazine 24-2 - 127
Instrumentation & Measurement Magazine 24-2 - 128
Instrumentation & Measurement Magazine 24-2 - 129
Instrumentation & Measurement Magazine 24-2 - 130
Instrumentation & Measurement Magazine 24-2 - 131
Instrumentation & Measurement Magazine 24-2 - 132
Instrumentation & Measurement Magazine 24-2 - Cover3
Instrumentation & Measurement Magazine 24-2 - Cover4
https://www.nxtbook.com/allen/iamm/25-8
https://www.nxtbook.com/allen/iamm/25-7
https://www.nxtbook.com/allen/iamm/25-6
https://www.nxtbook.com/allen/iamm/25-5
https://www.nxtbook.com/allen/iamm/25-4
https://www.nxtbook.com/allen/iamm/25-3
https://www.nxtbook.com/allen/iamm/instrumentation-measurement-magazine-25-2
https://www.nxtbook.com/allen/iamm/25-1
https://www.nxtbook.com/allen/iamm/24-9
https://www.nxtbook.com/allen/iamm/24-7
https://www.nxtbook.com/allen/iamm/24-8
https://www.nxtbook.com/allen/iamm/24-6
https://www.nxtbook.com/allen/iamm/24-5
https://www.nxtbook.com/allen/iamm/24-4
https://www.nxtbook.com/allen/iamm/24-3
https://www.nxtbook.com/allen/iamm/24-2
https://www.nxtbook.com/allen/iamm/24-1
https://www.nxtbook.com/allen/iamm/23-9
https://www.nxtbook.com/allen/iamm/23-8
https://www.nxtbook.com/allen/iamm/23-6
https://www.nxtbook.com/allen/iamm/23-5
https://www.nxtbook.com/allen/iamm/23-2
https://www.nxtbook.com/allen/iamm/23-3
https://www.nxtbook.com/allen/iamm/23-4
https://www.nxtbookmedia.com