The Future is Here: Sweat-Powered Smart Tatoo

smart_tatoosSmart tattoos are the hot ticket item of modern medicine, combining ultra-thin electronics with flexible materials. When they become commonplace, they will be a great way to monitor vital signs and health. The only thing that seems to be holding them back, is finding a way to power them. Tiny batteries are one possibility, but lack practicality, and microwaves are several years away from being feasible.

Luckily, Joseph Wang – a researchers from UCSD – has come up with a way to generate power for these devices without using any external equipment. The secret, is to harness electrons from lactate acid secreted in sweat. These acids are produced when our muscles work to exhaustion, a waste product that causes muscles to “burn”, but which the brain thrives upon. Hence why it is the endpoint in lactate’s metabolization cycle. lactate was discovered to be released in sweat, exercise physiologists began developing sensor technology to measure its levels in the sweat and blood. Wang has taken the next logical step of adding provisions to accumulate charge when lactate is enzymatically sensed. By embedding enzymes that process lactate into the tattoo, he was able to extract 70 microwatts per cm² of skin.

The only catch with this tattoo is that you need to be hot – as in pedaling your heart out on a bike for 30 minutes – to get the lactate out. That, however, may not be a barrier to this technology, since it is possible to selectively activate the sympathetic nerves that control the sweat glands in a discrete patch of skin. That way, you override the normal control and can sweat without the heat or exertion.

flexible_elecThe other part of the puzzle would be to actually generate the lactic acid. Preferably, this would be done locally as well, rather than having to have high levels circulating in the blood. But in the end, such steps would not even be necessary considering that a vitals and health monitoring that occurs into a workout – after an initial warm-up and good sweat have taken place – could be just what the doctor ordered (no pun intended!).

Other researchers have already imagined e-tattoos to read your thoughts and desires, either by reading unvocalized words or EEG readings. And compared to past generations of sensor devices, these tattoos represent a sophisticated electronic package with on-board signal processing and communications. With a discrete way to power such devices, a formidable tool for self discovery might be had.


The Future of Medicine: Tiny Bladder and Flashlight Sensors

heart_patchesThere’s seems to be no shortage of medical breakthroughs these days! Whether it’s bionic limbs, 3-D printed prosthetic devices, bioprinting, new vaccines and medicines, nanoparticles, or embedded microsensors, researchers and medical scientists are bringing innovation and technological advancement together to create new possibilities. And in recent months, two breakthrough in particular have bbecome the focus of attention, offering the possibility of smarter surgery and health monitoring.

First up, there’s the tiny bladder sensor that is being developed by the Norwegian research group SINTEF. When it comes to patients suffering from paralysis, the fact that they cannot feel when their bladders are full, para and quadriplegics often suffer from pressure build-up that can cause damage to the bladder and kidneys. This sensor would offer a less invasive means of monitoring their condition, to see if surgery is required or if medication will suffice.

pressuresensorPresently, doctors insert a catheter into the patient’s urethra and fill their bladder with saline solution, a process which is not only uncomfortable but is claimed to provide an inaccurate picture of what’s going on. By contrast, this sensor can be injected directly into the patients directly through the skin, and could conceivably stay in place for months or even years, providing readings without any discomfort, and without requiring the bladder to be filled mechanically.

Patients would also able to move around normally, plus the risk of infection would reportedly be reduced. Currently readings are transmitted from the prototypes via a thin wire that extents from the senor out through the skin, although it is hoped that subsequent versions could transmit wirelessly – most likely to the patient’s smartphone. And given that SINTEF’s resume includes making sensors for the CERN particle collider, you can be confident these sensors will work!

senor_cern_600Next month, a clinical trial involving three spinal injury patients is scheduled to begin at Norway’s Sunnaas Hospital. Down the road, the group plans to conduct trials involving 20 to 30 test subjects. Although they’re currently about to be tested in the bladder, the sensors could conceivably be used to measure pressure almost anywhere in the body. Conceivably, sensors that monitor blood pressure and warn of aneurisms or stroke could be developed.

Equally impressive is the tiny, doughnut-shaped sensor being developed by Prof. F. Levent Degertekin and his research group at the George W. Woodruff School of Mechanical Engineering at Georgia Tech. Designed to assist doctors as they perform surgery on the heart or blood vessels, this device could provide some much needed (ahem) illumination. Currently, doctors and scientists rely on images provided by cross-sectional ultrasounds, which are limited in terms of the information they provide.

tiny_flashlightAs Degertekin explains:

If you’re a doctor, you want to see what is going on inside the arteries and inside the heart, but most of the devices being used for this today provide only cross-sectional images. If you have an artery that is totally blocked, for example, you need a system that tells you what’s in front of you. You need to see the front, back, and sidewalls altogether.

That’s where their new chip comes into play. Described as a “flashlight” for looking inside the human body, it’s basically a tiny doughnut-shaped sensor measuring 1.5 millimeters (less than a tenth of an inch) across, with the hole set up to take a wire that would guide it through cardiac catheterization procedures. In that tiny space, the researchers were able to cram 56 ultrasound transmitting elements and 48 receiving elements.

georgia-tech-flashlight-vessels-arteries-designboom03So that the mini monitor doesn’t boil patients’ blood by generating too much heat, it’s designed to shut its sensors down when they’re not in use. In a statement released from the university, Degertekin explained how the sensor will help doctors to better perform life-saving operations:

Our device will allow doctors to see the whole volume that is in front of them within a blood vessel. This will give cardiologists the equivalent of a flashlight so they can see blockages ahead of them in occluded arteries. It has the potential for reducing the amount of surgery that must be done to clear these vessels.

Next up are the usual animal studies and clinical trials, which Degertekin hopes will be conducted by licensing the technology to a medical diagnostic firm. The researchers are also going to see if they can make their device even smaller- small enough to fit on a 400-micron-diameter guide wire, which is roughly four times the diameter of a human hair. At that size, this sensor will be able to provide detailed, on-the-spot information about any part of the body, and go wherever doctors can guide it.

Such is the nature of the new age of medicine: smaller, smarter, and less invasive, providing better information to both save lives and improve quality of life. Now if we can just find a cure for the common cold, we’d be in business!