blood pressure

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A light grey box about the size of a brick with exposed screws held in a person's hand. There are two illuminated push buttons on the bottom left of the top panel. One is illuminated blue while the other is green. A small square screen sits next to a bank of nine different sections with an LED indicator and text of "HW, BAT, HBEAT, ECG, LOD +, LOD -, PPG, Pump, Valve."

Open Cardiography Signal Measuring Device

November 13, 2024 by 10 Comments

Much of the world’s medical equipment is made by a handful of monopolistic megacorps, but [Milos Rasic] built an open cardiography signal measuring device for his master’s thesis.

Using a Pi Pico W for the brains, [Rasic]’s device can record, store and analyze the data from an arm cuff, stethoscope, electrocardiograph (ECG), and pulse oximeter. This data can be used for monitoring blood pressure in patients and he has results from some of his experiments to determine the optimal algorithm for the task on the GitHub if you really want to get into the nitty gritty details.

Inside the brick-sized enclosure is the custom PCB, an 18650 Li-ion cell, and a pneumatic assembly for the arm cuff. Medical sensors attach via GX12 connectors on the back, a USB type B connector is used for data, and a USB C connector provides power for the device. The brightly colored labels will no doubt come in handy in a clinical setting where you really want to be sure you’ve got everything plugged in correctly.

Want more open medical equipment? How about an open ECG or this less accurate, but more portable, credit card ECG? We’d be remiss not to mention the huge amount of work on ventilators during the worst days of the COVID-19 pandemic as well.

3D printed ring with 4-integrated electrodes for measuring bioimpedance for measuring blood pressure from the finger

Smart Ring Measures Blood Pressure

November 6, 2023 by 17 Comments

Continuous blood pressure monitoring has always been a major challenge for the biohacking community. Those giant arm cuffs aren’t exactly the kind of thing you want to wear all day and the wrist monitors aren’t super great either. So, [Kaan] and his research team set out to create a better continuous blood pressure monitor. This time as a ring.

When your heart beats, the volume of blood in the blood vessels increases ever so slightly. This increase in volume results in a decrease in electrical impedance because blood is fairly conductive. We’ve seen a similar volume measurement using light for detecting heart rate, but [Kaan] says with impedance, you won’t need to worry about the effect of skin tone on the accuracy of the measurement.

As far as the hardware is concerned, they inject a small, constant 10 kHz sinusoidal current into the finger through 2 current-injecting electrodes, and then measure the resulting voltage drop across the finger with two sensing electrodes, a standard 4-probe Kelvin approach. Their results seem pretty good. They are within 5.27 millimeters of mercury (mmHg) of the gold standard for systolic blood pressure and 3.87 mmHg for diastolic blood pressure across 10 subjects, which they say are within the American Association for the Advancement of Medical Instrumentation’s (AAMI) guidelines. That’s definitely something to catch your attention.

We’ve seen several attempts to measure blood pressure using the analogous photoplethysmography technique, but those generally don’t seem to work out. Will the impedance plethysmography approach overcome the optical technique’s shortcomings? Only time will tell.

Blood Pressure Monitor For Under $1

June 20, 2023 by 22 Comments

Medical equipment is not generally known for being inexpensive, with various imaging systems usually weighing in at over a million dollars, and even relatively simpler pieces of technology like digital thermometers, stethoscopes, and pulse oximeters coming in somewhere around $50. As the general pace of technological improvement continues on we expect marginal decreases in costs, but every now and then a revolutionary piece of technology will drop the cost of something like a blood pressure monitor by over an order of magnitude.

Typically a blood pressure monitor involves a cuff that pressurizes against a patient’s arm, and measures the physical pressure of the blood as the heart forces blood through the area restricted by the cuff. But there are some ways to measure blood pressure by proxy, instead of directly. This device, a small piece of plastic with a cost of less than a dollar, attaches to a smartphone near the camera sensor and flashlight. By pressing a finger onto the device, the smartphone uses the flashlight and the camera in tandem to measure subtle changes in the skin, which can be processed in an app to approximate blood pressure.

The developers of this technology note that it’s not a one-to-one substitute for a traditional blood pressure monitor, but it is extremely helpful for those who might not be able to afford a normal monitor and who might otherwise go undiagnosed for high blood pressure. Almost half of adults in the US alone have issues relating to blood pressure, so just getting information at all is the hurdle this device is attempting to overcome. And, we’ll count it as a win any time medical technology becomes more accessible, more inexpensive, or more open-source.

Blood Pressure Monitoring, Courtesy Of Cameras And AI

December 21, 2022 by 60 Comments

At the basic level, methods of blood pressure monitoring have slowly changed in the last few decades. While most types of sphygmomanometer still rely on a Velcro cuff placed around the arm, the methodology used in measurement varies. Analog mercury and aneroid types still abound, while digital blood pressure monitors using electrical sensors have become mainstream these days.

Researchers have now developed a new non-invasive method of measurement that does away with the arm cuff entirely. The method relies entirely on video capture with a camera and processing via AI.

Continue reading “Blood Pressure Monitoring, Courtesy Of Cameras And AI” →

How To Monitor Blood Pressure Without Raising It

February 27, 2021 by 16 Comments

Does anyone actually enjoy the sensation of being squeezed by a blood pressure cuff? Well, as Mom used to say, it takes all kinds. For those who find the feeling nearly faint-inducing, take heart: researchers at UC San Diego have created a non-invasive medical wearable with a suite of sensors that can measure blood pressure and monitor multiple biochemicals at the same time.

The device is a small, flexible patch that adheres to the skin. So how does it manage to measure blood pressure without causing discomfort? The blood pressure sensor consists of eight customized piezoelectric transducers that bounce ultrasonic waves off the near and far walls of the artery. Then the sensor calculates the time of flight of the resulting echoes to gauge arterial dilation and contraction, which amounts to a blood pressure reading.

This patch also has a chemical sensor that uses a drug called pilocarpine to induce the skin to sweat, and then measures the levels of lactate, caffeine, and alcohol found within. To monitor glucose levels, a mild current stimulates the release of interstitial fluid — the stuff surrounding our cells that’s rife with glucose, salt, fatty acids, and a few minerals. This is how continuous glucose monitoring for diabetes patients works today. You can check out the team’s research paper for more details on the patch and its sensors.

In the future, the engineers are hoping to add even more sensors and develop a wireless version that doesn’t require external power. Either way, it looks much more comfortable and convenient than current methods.

Toilet Seat Could Save Your Ass

February 12, 2019 by 20 Comments

Our morning routine could be appended to something like “breakfast, stretching, sit on a medical examiner, shower, then commute.” If we are speaking seriously, we don’t always get to our morning stretches, but a quick medical exam could be on the morning agenda. We would wager that a portion of our readers are poised for that exam as they read this article. The examiner could come in the form of a toilet seat. This IoT throne is the next device you didn’t know you needed because it can take measurements to detect signs of heart failure every time you take a load off.

Tracking heart failure is not just one test, it is a buttload of tests. Continuous monitoring is difficult although tools exist for each test. It is unreasonable to expect all the at-risk people to sit at a blood pressure machine, inside a ballistocardiograph, with an oximeter on their fingers three times per day. Getting people to browse Hackaday on their phones after lunch is less of a struggle. When the robots overthrow us, this will definitely be held against us.

We are not sure if this particular hardware will be open-source, probably not, but there is a lesson here about putting sensors where people will use them. Despite the low rank on the glamorous scale, from a UX point of view, it is ingenious. How can we flush out our own projects to make them usable? After all, if you build a badass morning alarm, but it tries to kill you, it will need some work and if you make a gorgeous clock with the numbers all messed up…okay, we dig that particular one for different reasons.

Via IEEE Spectrum.

Wireless Wearable Watches Your Vital Signs

March 13, 2017 by 10 Comments

Is it [Dr. McCoy]’s long-awaited sickbay biobed, with wireless sensing and display of vital signs? Not quite, but this wearable patient monitor comes pretty close. And from the look of it, [Arthur]’s system might even monitor a few more parameters than [Bones]’ bleeping bed from the original series.

Starting with an automatic blood pressure cuff that [Arthur] had previously reversed engineered, he started adding sensors. Pulse, ECG, respiration rate, galvanic skin response, and body temperature are all measured from one compact, wrist-wearable device. It’s not entirely wireless – the fingertip pulse oximetry dongle and chest electrodes still need to be wired back to the central unit – but the sensors all talk to a Teensy 3.2 which then communicates to an Android app over Bluetooth, so there’s no need to be tethered to the display. And speaking of electrodes, we’re intrigued by the ADS1292 chip [Arthur] uses, which not only senses the heart’s electrical signals but also detects respirations by the change in impedance as the chest wall expands and contracts. Of course there’s also pneumography via radar that could be rolled into this sensor suite.

It’s all pretty cool, and we can easily see a modified version of this app displayed on a large tablet or monitor being both an accurate prop reconstruction and a useful medical device.

Continue reading “Wireless Wearable Watches Your Vital Signs” →