In New Doctor’s Office, Stethoscope Wears You

November 26, 2023 by Al Williams 28 Comments

The medical professional wearing a stethoscope is a familiar image, but Northwestern University wants to change that. Instead of someone hanging an ancient device around their neck to listen inside of you, they want to put sticky sensors on patients to continuously monitor sounds from hearts, lungs, and the GI tract.

The tiny devices stick to your skin and wirelessly beam audio to clinicians for analysis. They’ve tested the devices on people ranging from people with chronic lung disease to premature babies. In fact, you can hear breath sounds (and crying) from a microphone attached to a baby in the video below. The device uses noise suppression to remove the crying sounds effectively.

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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 Orlando Hoilett 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.

Open Source Ear Monitoring Platform Listens To Your Ears

October 17, 2023 by Richard Baguley 17 Comments

All sorts of exciting things happen in your ears, and now there is a good open source way to monitor them. Open Earable is a new project from a group of researchers and companies that monitors and records what is going on in your ear.

The project is designed as an easy-to-build, cheap way for audiologists and others to capture data about what is happening inside and around the ear. It’s a clip-on device that looks like a small hearing aid but has a six-degree Inertial Measurement Unit (IMU) and several other sensors to measure things around your ear and inside the ear canal. A pressure and temperature sensor measures the air pressure and temperature just inside the ear canal, and a small speaker can squirt sound right in there.

A button on the outside allows the user to control the device, and it can play back or record sound to the internal SD card memory. These are all controlled by an Arduino that includes Bluetooth Low Energy. The existing design only allows you to play a stored WAV file, not streaming audio. That’s a solvable problem, though, so it could also be turned into a set of hacker headphones.

Joking aside, this looks like an exciting research project and a useful tool for researchers. The GitHub repository for version 1.3 of the project lays it all out, including a full BoM and code, and the STL files for the case and PCB designs are in the Resources section of the site.

[Updated 18/10/2023 to correct IMU to Measurement, not Management. Intertial management needs a different set of devices]

Implant Fights Diabetes By Making Insulin And Oxygen

October 10, 2023 by Dan Maloney 13 Comments

Type 1 diabetes remains a problem despite having an apparently simple solution: since T1D patients have lost the cells that produce insulin, it should be possible to transplant those cells into their bodies and restore normal function. Unfortunately, it’s not actually that simple, and it’s all thanks to the immune system, which would attack and destroy transplanted pancreas cells, whether from a donor or grown from the patient’s own stem cells.

That may be changing, though, at least if this implantable insulin-producing bioreactor proves successful. The device comes from MIT’s Department of Chemical Engineering, and like earlier implants, it relies on encapsulating islet cells, which are the insulin-producing cells within the pancreas, inside a semipermeable membrane. This allows the insulin they produce to diffuse out into the blood, and for glucose, which controls insulin production in islet cells, to diffuse in. The problem with this arrangement is that the resource-intensive islet cells are starved of oxygen inside their capsule, which is obviously a problem for the viability of the implant.

The solution: electrolysis. The O₂-Macrodevice, as the implant is called, uses a tiny power-harvesting circuit to generate oxygen for the islet cells directly from the patient’s own interstitial water. The circuit applies a current across a proton-exchange membrane, which breaks water molecules into molecular oxygen for the islet cells. The hydrogen is said to diffuse harmlessly away; it seems like that might cause an acid-base imbalance locally, but there are plenty of metabolic pathways to take care of that sort of thing.

The implant looks promising; it kept the blood glucose levels of diabetic mice under control, while mice who received an implant with the oxygen-generating cell disabled started getting hyperglycemic after two weeks. What’s really intriguing is that the study authors seem to be thinking ahead to commercial production, since they show various methods for mass production of the cell chamber from standard 150-mm silicon wafers using photolithography.

Type 1 diabetics have been down the “artificial pancreas” road before, so a wait-and-see approach is clearly wise here. But it looks like treating diabetes less like a medical problem and more like an engineering problem might just pay dividends.

Autonomous Wheelchair Lets Jetson Do The Driving

October 4, 2023 by Tom Nardi 8 Comments

Compared to their manual counterparts, electric wheelchairs are far less demanding to operate, as the user doesn’t need to have upper body strength normally required to turn the wheels. But even a motorized wheelchair needs some kind of input from the user to control it, which still may pose a considerable challenge depending on the individual’s specific abilities.

Hoping to improve on the situation, [Kabilan KB] has developed a self-driving electric wheelchair that can navigate around obstacles by feeding the output of an Intel RealSense Depth Camera and LiDAR module into a Jetson Nano Developer Kit running OpenCV. To control the actual motors, the Jetson is connected to an Arduino which in turn is wired into a common L298N motor driver board.

As [Kabilan] explains on the NVIDIA Blog, he specifically chose off-the-shelf components and the most affordable electric wheelchair he could find to bring the total cost of the project as low as possible. An undergraduate from the Karunya Institute of Technology and Sciences in Coimbatore, India, he notes that this sort of assistive technology is usually only available to more affluent patients. With his cost-saving measures, he hopes to address that imbalance.

While automatic obstacle avoidance would already be a big help for many users, [Kabilan] imagines improved software taking things a step further. For example, a user could simply press a button to indicate which room of the house they want to move to, and the chair could drive itself there automatically. With increasingly powerful single-board computers and the state of open source self-driving technology steadily improving, it’s not hard to imagine a future where this kind of technology is commonplace.

ARPA-H Moonshot Project Aims To Enable 3D Printing Of Human Organs

October 4, 2023 by Maya Posch 9 Comments

The field of therapeutic cloning has long sought to provide a way to create replacement organs and tissues from a patient’s own cells, with the most recent boost coming from the US Advanced Research Projects Agency for Health (ARPA-H) and a large federal contract awarded to Stanford University.

Patients on the organ donation waiting list in the US (Source: HRSA)

The creatively named Health Enabling Advancements through Regenerative Tissue Printing (HEART) project entails a 26.3 million USD grant that will be used to create a functioning bioprinter backed by a bank of bioreactors. Each bioreactor will cultivate a specific type of cell, which will then be ‘printed’ in its proper place to gradually build up the target organ or tissue. The project’s five year goal is the printing of a fully functioning human heart and implanting it into a pig.

Assuming this is successful, the general procedure can then be refined to allow for testing with human patients, as well as the bioprinting of not just hearts, but also lungs, kidneys and much more. The lead investigator at Stanford University, [Mark Skylar-Scott], cautions that use with human patients is likely to be still decades off. But the lifesaving potential of this technology, once matured, is staggering. This is highlighted by data from the US HRSA, with over 42,000 transplants in 2022 in the US alone, with over a hundred-thousand patients waiting and 17 people who die each day before an organ becomes available.

Bioadhesive Polymer Semiconductors For In-Vivo Sensors

October 3, 2023 by Maya Posch 2 Comments

What do you do when you want to stick an electrode or even an couple of sensors to an internal organ, such as a heart? Generally you’d use some kind of special adhesive, or sutures to ensure that the item remains firmly in place and doesn’t migrate to somewhere else within the chest cavity or among the intestines. According to a new study (press release) by Nan Li and colleagues in Science there may however be a more elegant method, using bioadhesive polymers.

The double-network copolymer is designed so that once put in the desired location it soaks up moisture and provides a dry interface for its bioadhesive properties. In addition, the resulting material is electrically conductive, with a measured charge-carrier mobility of ~1 square centimeter per volt per second.

Using thus manufactured electrodes were applied to both an isolated rat heart and in vivo rat muscles to measure electrical currents produced by each respective tissue type. The authors of the study envision that using this technology more complicated interfaces and sensors can be developed that would interface directly with organs and related. The claimed biocompatibility would also allow for such devices to be left in-situ for extended periods of time, which could be a boon for a wide range of medical conditions where continuous monitoring is a crucial element.