The accelerometer in the awarewear wearables allow for the measurement of user activity as well as motion during measurement, which may be a factor for accuracy determination in the medical measurement results. The awarewear technology, is based on MEMs which measures the change of linear motion by applying the sensing principle of capacitive detection. We employ technology to measure over two ranges of accelerations, first during normal motions and activities – walking etc. and secondly during potentially concussive events – collisions, falls etc. then combine these two data sets to provide a comprehensive record of bodily activity for the user.
Pulse oximeters measure how much of the hemoglobin in blood is carrying oxygen (oxygen saturation). Oxygenated and de-oxygenated hemoglobin has a different color (red and blue in appearance), in the body veins return blood to the lungs for oxygenation which is then transported to the cells that use the oxygen in the arteries. This photoplethysmographic (PPG) measurement is completed by using two different wavelength (color) LEDs which emits narrow wavelength bands of light; the chosen wavelengths are 660 (red/green) and 940 (infra-red)nm, because reduced hemoglobin absorbs more at 660 nm and oxygenated hemoglobin absorbs more at 940 nm, then by measurement of the reflectance or transmittance of that wavelength of light a determination of the blood oxygenation can be made. The system we will use employs two green LEDs and one infra-red LED.
The primary measurements are based on Pulse Wave Velocity (PWV) and Pulse Transit Time (PTT). PWV is the velocity at which the blood pressure pulse propagates through the circulatory system, usually an artery or a combined length of arteries. PWV is used clinically as a measure of arterial stiffness and can be readily measured non-invasively. The PTT is the time it takes the Pulse Pressure (PP) waveform to propagate through a length of the arterial tree.
The pulse pressure waveform results from the ejection of blood from the left ventricle and moves with a velocity much greater than the forward movement of the blood itself. To measure pulse transit time, record the onset of the R-wave from an ECG type measurement and record the pulse waveform at the fingertip. The delay between these two then provides for a calculation of the blood pressure both systolic and diastolic. The result accuracy is then a function of the data used to calculate this value, including age, height, weight etc.
Using Bluetooth, a wireless technology standard used for exchanging data between fixed and mobile devices over short distances using short-wavelength UHF radio waves in the industrial, scientific and medical radio bands, from 2.402 GHz to 2.480 GHz, in the device and connecting it directly to the COTS device (typically phone or laptop) of the patient, the sensor data will be encrypted and sent to the cloud.
The patient will need to register themselves and the device in a dedicated web portal. Information will be sent in real-time as and when generated.
A normal heart beat contains a P wave, a QRS complex which consists of a Q wave -the downward deflection immediately following the P wave, then the R wave follows as an upward deflection, and the S wave which is the downward deflection after the R wave, and finally an ST segment. The timing between the successive QRS complex, is used to calculate heart rate.
- The P wave is a small semi-circular shape located right before the tall QRS complex. It represents the electrical activity of the atria (“atrial depolarization”), which are the two small chambers located at the top of the heart.
- The QRS complex is the tallest most visible aspect of the ECG trace. It is usually pointy, like a tall, thin triangle and very easy to recognize. It represents the electrical activity of the ventricles (“ventricular depolarization”), which are the two large chambers located at the bottom of the heart that forcefully pump blood throughout the body.
- The ST segment directly follows the tall QRS complex. It is actually the flat area prior to the next semi-circular shape on the ECG (which is the T wave). The importance of this flat segment (the ST segment), located right after the QRS complex, is that it provides important information to physicians about things such as potential heart attacks. Measurements either above or below parameters will create alert messages.
The galvanic skin response (GSR, which falls under the umbrella term of electrodermal activity, or EDA) refers to changes in sweat gland activity that are reflective of the intensity of our emotional state, otherwise known as emotional arousal. While sweat secretion plays a major role for thermoregulation and sensory discrimination, changes in skin conductance are also triggered robustly by emotional stimulation: the higher the arousal, the higher the skin conductance.
The amount of sweat glands varies across the human body, but is the highest in hand and foot regions (200–600 sweat glands per cm2), where the GSR signal is typically collected from.
Skin conductance is not under conscious control. Instead, it is modulated autonomously by sympathetic activity which drives aspects of human behavior, as well as cognitive and emotional states. Skin conductance therefore offers direct insights into autonomous emotional regulation.
On a simpler note, GSR also provides a direct measurement that the device is in contact with the skin and so is being worn correctly
The Global Positioning System (GPS) is a navigation system using satellites, a receiver and algorithms to synchronize location, velocity and time data for air, sea and land travel.
Though GPS is a subset of GNSS, receivers are differentiated as GPS (meaning GPS-only) or GNSS. A GPS receiver is only capable of reading information from satellites in the GPS satellite network, while the typical GNSS device can receive information from both GPS and GLONASS (or more than these two systems) at a time.
A GNSS receiver has 60 satellites available for viewing. While a device only needs three satellites to determine its location, accuracy is improved with a larger number of satellites. The satellite system consists of a constellation of satellites in Earth-centered orbital planes, each with multiple satellites, orbiting at 13,000 miles (20,000 km) above Earth and traveling at a speed of 8,700 mph (14,000 km/h).
While we only need three satellites to produce a location on earth’s surface, a fourth satellite is often used to validate the information from the other three. The fourth satellite also moves us into the third-dimension and allows us to calculate the altitude of a device.
A gyroscope is used to measure rotation around an axis. In our case we measure rotation and rotational acceleration around three axes. This allows us to map the motions of the body when it comes to a spin – and so for a head event if a blow occurs to spin the head this type of event can cause damage at the base of the brain where the cerebral cortex connects to the brain. Rotational acceleration is often a large factor in concussion outcomes as the amount of rotation of the head can significantly impact where and what damage occurs to the brain, the multi dimensional motions that occur in an event, must all be recorded and mapped to determine likely impacts and to map outcomes.
The heart rate/pulse rate is determined from an ECG measurement. From the separation between R waves of a heart-beat on the ECG trace, you are be able to measure/calculate the heart rate directly. A normal heart beat contains a P wave, a QRS complex which consists of a Q wave -the downward deflection immediately following the P wave, then the R wave follows as an upward deflection, and the S wave which is the downward deflection after the R wave, and finally an ST segment. The timing between the successive QRS complex, is used to calculate heart rate.
The laws of physics are something we “learned” (or shut off in class to 😊) in school, but they affect us every day and every moment of every day. Sir Isaac Newton formulated the first description of forces with his simple first law: “Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it”. Translating this to every day, if two football players collide their motion in a straight line is changed by the forces “impressed” by the collision. The amount of motion change is described by Newton’s second law: “Force is equal to the change in momentum (mV) per change in time. For a constant mass, force equals mass times acceleration”. Again, in every day language, the more force I apply the bigger the change – the harder the hit.
A magnetometer measures the direction of the Earth’s magnetic field, this allows us to know the direction (relative to the compass North, South, East and West)
The ability to track and classify motions is important to understanding the activity level of the user, the device can detect if the wearer is sleeping, running, walking, sneezing, jumping, coughing etc. These classifications are completed by analyzing the combination of motions recorded by the accelerometers, gyroscopes and magnetometers in the device.
NFC (Near Field Communication) is used to contain information in the device such as the device serial number and allow external devices to read this with close proximity transfer. The NFC tag built into the device then allows simple pairing of the device to the user information and so linking the device to the database in the cloud.
The awarewear devices all use advanced rechargeable Li-Ion batteries, the use of primary cells in electronics seems like an ancient technology and we have certainly moved on from having to have a stock of AA batteries in the drawer! Our devices include the battery and recharging circuits to simplify things for you, just plug the device into a USB source (usually a wall adapter, battery pack or your car) or place on a charger surface for the wirelessly rechargeable devices, and the device then does all of the work to complete a recharge safely and conveniently.
The concept of “social distancing” also called “physical distancing,” means keeping space between yourself and other people outside of your home. This is useful to avoid contraction of virus and bacterial infections spread by airborne particles, released during breathing, coughing, and sneezing by infected individuals.
To practice social or physical distancing:
- Stay at least 6 feet (about 2 arms’ length) from other people
- Do not gather in groups
- Stay out of crowded places and avoid mass gatherings
In addition to everyday steps to prevent COVID-19, keeping space between you and others is one of the best tools we have to avoid being exposed to this virus and slowing its spread locally and across the country and world.
Limit close contact with others outside your household in indoor and outdoor spaces. Since people can spread the virus before they know they are sick, it is important to stay away from others when possible, even if you—or they—have no symptoms. Social distancing is especially important for people who are at higher risk for severe illness from COVID-19.
The awarewear devices include a contact thermometer, this will allow a person’s temperature to be taken almost continuously (at regular rapid intervals).
Contact Temperature Accuracy (0.2oC between 37 and 39C)
We will also have a non-contact, thermal IR approach, but with reduced accuracy (0.25oC between 35 and 42C, for an ambient between 15 and 40C).
Body temperature can be measured in a number of ways. Traditionally, body temperature has been measured using contact thermometers that are placed on the forehead or in the mouth, ear, armpit or rectum. Non-contact thermometers allow a person’s temperature to be taken with minimal (tympanic) or no (Non-contact infrared thermometer [NCIT], thermal scanner) contact with the person. This means temperature can be measured without the discomfort of having to sit still with a thermometer in the mouth, armpit, or rectum long enough to obtain a correct temperature reading.
The advantage of continuous reading is that the effect of external, environmental impacts can be reduced and also errors introduced by measurement methods can also be reduced to provide a consistent and reliable body temperature measurement.
Wireless communication is the electromagnetic transfer of information between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few tens of meters for Bluetooth. The use of Wireless allows the device to have the freedom to move around without being harnessed to a fixed point by wires.
The awearwear devices are sealed and waterproofed allowing the user to be as active as possible without concerns for the device well being. This means you can swim, run and play in the rain, sun and snow as you wish.
© 2020 awarewear