Tag Archives: Patty Wellborn

A nanocomposite biomaterial heart valve from the University of British Columbia (Canada)

I wish the folks at the University of British Columbia (UBC) would include more technical/scientific information in their news releases about research. For those who do like a little more technical information, I included the paper’s abstract at the end of this post.

A March 25, 2019 news item on ScienceDaily trumpets the UBC (Okanagan campus) research,

Researchers at UBC have created the first-ever nanocomposite biomaterial heart-valve developed to reduce or eliminate complications related to heart transplants.

By using a newly developed technique, the researchers were able to build a more durable valve that enables the heart to adapt faster and more seamlessly.

A March 25, 2019 UBC news release (also on EurekAlert) by Patty Wellborn, which originated the news item, gives an accessible description of the ‘new’ valve,

Assistant Professor Hadi Mohammadi runs the Heart Valve Performance Laboratory (HVPL) through UBC Okanagan’s School of Engineering. Lead author on the study, he says the newly developed valve is an example of a transcatheter heart valve, a promising new branch of cardiology. These valves are unique because they can be inserted into a patient through small incisions rather than opening a patient’s chest–a procedure that is generally safer and much less invasive.

“Existing transcatheter heart valves are made of animal tissues, most often the pericardium membrane from a cow’s heart, and have had only moderate success to date,” explains Mohammadi. “The problem is that they face significant implantation risks and can lead to coronary obstruction and acute kidney injury.”

The new valve solves that problem by using naturally derived nanocomposites–a material assembled with a variety of very small components–including gels, vinyl and cellulose. The combination of their new material with the non-invasive nature of transcatheter heart valves makes this new design very promising for use with high-risk patients, according to Mohammadi.

“Not only is the material important but the design and construction of our valve means that it lowers stress on the valve by as much as 40 per cent compared to valves currently available,” says Dylan Goode, a graduate researcher at the HVPL. “It is uniquely manufactured in one continuous form, so it gains strength and flexibility to withstand the circulatory complications that can arise following transplantation.”

Working with researchers from Kelowna General Hospital and Western University, the valve will now undergo vigorous testing to perfect its material composition and design. The testing will include human heart simulators and large animal in-vivo studies. If successful, the valve will then proceed to clinical patient testing.

“This has the potential to become the new standard in heart valve replacement and to provide a safer, longer-term solution for many patients.”

The new design was highlighted in a paper published this month in the Journal of Engineering in Medicine with financial support from the Natural Sciences and Engineering Research Council of Canada [NSERC] .

Here’s a link to and a citation for the paper,

Proposed percutaneous aortic valve prosthesis made of cryogel by Hadi Mohammadi, Dylan Goode, Guy Fradet, Kibret Mequanint. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2019; 095441191983730 DOI: 10.1177/0954411919837302 First Published March 20, 2019

This paper is behind a paywall.

As promised, here’s the abstract,

Transcatheter heart valves are promising for high-risk patients. Generally, their leaflets are made of pericardium stented in a Nitinol basket. Despite their relative success, they are associated with significant complications such as valve migration, implantation risks, stroke, coronary obstruction, myocardial infraction, acute kidney injury (which all are due to the release of detached solid calcific pieces in to the blood stream) and expected issues existing with tissue valves such as leaflet calcification. This study is an attempt to fabricate the first ever polymeric percutaneous valves made of cryogel following the geometry and mechanical properties of porcine aortic valve to address some of the above-mentioned shortcomings. A novel, one-piece, tricuspid percutaneous valve, consisting of leaflets made entirely from the hydrogel, polyvinyl alcohol cryogel reinforced by bacterial cellulose natural nanocomposite, attached to a Nitinol basket was developed and demonstrated. Following the natural geometry of the valve, a novel approach was applied based on the revolution about an axis of a hyperboloid shape. The geometry was modified based on avoiding sharp warpage of leaflets and removal of the central opening orifice area of the valve when valve is fully closed using the finite element analysis. The modified geometry was replaced by a cloud of (control) points and was essentially converted to Bezier surfaces for further adjustment. A cavity mold was then designed and fabricated to form the valve. The fabricated valve was sewn into the Nitinol basket which is covered by Dacron cloth. The models presented in this study merit further development and revisions for both aortic and mitral positions.

So, this new valve partially consists of bacterial cellulose and the design is based on porcine (pig) valves. Cellulose is the most abundant organic material on earth and if it forms part of the nanocomposite, I’d expect to see the word ‘nanocellulose’ mentioned somewhere. What puzzles me is the ‘bacterial cellulose’, a term that is unfamiliar to me. Anyone who cares to clarify the matter for me, please feel free to leave a comment.

Regarding the pig valve, I understand that heart patients who require valves have a choice of a pig valve or a mechanical valve. Apparently, people with porcine valves don’t need to take drugs to counteract rejection amongst other advantages but the valves do have a shorter life span (10 to 15 years) in addition to the other shortcomings mentioned in the abstract.

Assuming I properly understand the abstract, this ‘nanocomposite’ valve could combine the advantages of the mechanical and porcine valves while offering more durability than either one.

Again, should anyone care to increase my understanding of the valves and the advantages of this new one, please do leave a comment.

Wearable technology: two types of sensors one from the University of Glasgow (Scotland) and the other from the University of British Columbia (Canada)

Sometimes it’s good to try and pull things together.

University of Glasgow and monitoring chronic conditions

A February 23, 2018 news item on phys.org describes the latest wearable tech from the University of Glasgow,

A new type of flexible, wearable sensor could help people with chronic conditions like diabetes avoid the discomfort of regular pin-prick blood tests by monitoring the chemical composition of their sweat instead.

In a new paper published in the journal Biosensors and Bioelectronics, a team of scientists from the University of Glasgow’s School of Engineering outline how they have built a stretchable, wireless system which is capable of measuring the pH level of users’ sweat.

A February 22, 2018 University of Glasgow press release, which originated the news item, expands on the theme,

Ravinder Dahiya

 Courtesy: University of Glasgow

 

Sweat, like blood, contains chemicals generated in the human body, including glucose and urea. Monitoring the levels of those chemicals in sweat could help clinicians diagnose and monitor chronic conditions such as diabetes, kidney disease and some types of cancers without invasive tests which require blood to be drawn from patients.

However, non-invasive, wearable systems require consistent contact with skin to offer the highest-quality monitoring. Current systems are made from rigid materials, making it more difficult to ensure consistent contact, and other potential solutions such as adhesives can irritate skin. Wireless systems which use Bluetooth to transmit their information are also often bulky and power-hungry, requiring frequent recharging.

The University of Glasgow team’s new system is built around an inexpensively-produced sensor capable of measuring pH levels which can stretch and flex to better fit the contours of users’ bodies. Made from a graphite-polyurethane composite and measuring around a single square centimetre, it can stretch up to 53% in length without compromising performance. It will also continue to work after being subjected to flexes of 30% up to 500 times, which the researchers say will allow it to be used comfortably on human skin with minimal impact on the performance of the sensor.

The sensor can transmit its data wirelessly, and without external power, to an accompanying smartphone app called ‘SenseAble’, also developed by the team. The transmissions use near-field communication, a data transmission system found in many current smartphones which is used most often for smartphone payments like ApplePay, via a stretchable RFID antenna integrated into the system – another breakthrough innovation from the research team.

The smartphone app allows users to track pH levels in real time and was demonstrated in the lab using a chemical solution created by the researchers which mimics the composition of human sweat.

The research was led by Professor Ravinder Dahiya, head of the University of Glasgow’s School of Engineering’s Bendable Electronics and Sensing Technologies (BEST) group.

Professor Dahiya said: “Human sweat contains much of the same physiological information that blood does, and its use in diagnostic systems has the significant advantage of not needing to break the skin in order to administer tests.

“Now that we’ve demonstrated that our stretchable system can be used to monitor pH levels, we’ve already begun additional research to expand the capabilities of the sensor and make it a more complete diagnostic system. We’re planning to add sensors capable of measuring glucose, ammonia and urea, for example, and ultimately we’d like to see a system ready for market in the next few years.”

The team’s paper, titled ‘Stretchable Wireless System for Sweat pH Monitoring’, is published in Biosensors and Bioelectronics. The research was supported by funding from the European Commission and the Engineering and Physical Sciences Research Council (EPSRC).

Here’s a link to and a citation for the paper,

Stretchable wireless system for sweat pH monitoring by Wenting Dang, Libu Manjakkal, William Taube Navaraj, Leandro Lorenzelli, Vincenzo Vinciguerra. Biosensors and Bioelectronics Volume 107, 1 June 2018, Pages 192–202 [Available online February 2018] https://doi.org/10.1016/j.bios.2018.02.025

This paper is behind a paywall.

University of British Columbia (UBC; Okanagan) and monitor bio-signals

This is a completely other type of wearable tech monitor, from a February 22, 2018 UBC news release (also on EurekAlert) by Patty Wellborn (A link has been removed),

Creating the perfect wearable device to monitor muscle movement, heart rate and other tiny bio-signals without breaking the bank has inspired scientists to look for a simpler and more affordable tool.

Now, a team of researchers at UBC’s Okanagan campus have developed a practical way to monitor and interpret human motion, in what may be the missing piece of the puzzle when it comes to wearable technology.

What started as research to create an ultra-stretchable sensor transformed into a sophisticated inter-disciplinary project resulting in a smart wearable device that is capable of sensing and understanding complex human motion, explains School of Engineering Professor Homayoun Najjaran.

The sensor is made by infusing graphene nano-flakes (GNF) into a rubber-like adhesive pad. Najjaran says they then tested the durability of the tiny sensor by stretching it to see if it can maintain accuracy under strains of up to 350 per cent of its original state. The device went through more than 10,000 cycles of stretching and relaxing while maintaining its electrical stability.

“We tested this sensor vigorously,” says Najjaran. “Not only did it maintain its form but more importantly it retained its sensory functionality. We have further demonstrated the efficacy of GNF-Pad as a haptic technology in real-time applications by precisely replicating the human finger gestures using a three-joint robotic finger.”

The goal was to make something that could stretch, be flexible and a reasonable size, and have the required sensitivity, performance, production cost, and robustness. Unlike an inertial measurement unit—an electronic unit that measures force and movement and is used in most step-based wearable technologies—Najjaran says the sensors need to be sensitive enough to respond to different and complex body motions. That includes infinitesimal movements like a heartbeat or a twitch of a finger, to large muscle movements from walking and running.

School of Engineering Professor and study co-author Mina Hoorfar says their results may help manufacturers create the next level of health monitoring and biomedical devices.

“We have introduced an easy and highly repeatable fabrication method to create a highly sensitive sensor with outstanding mechanical and electrical properties at a very low cost,” says Hoorfar.

To demonstrate its practicality, researchers built three wearable devices including a knee band, a wristband and a glove. The wristband monitored heartbeats by sensing the pulse of the artery. In an entirely different range of motion, the finger and knee bands monitored finger gestures and larger scale muscle movements during walking, running, sitting down and standing up. The results, says Hoorfar, indicate an inexpensive device that has a high-level of sensitivity, selectivity and durability.

Hoorfar and Najjaran are both members of the Okanagan node of UBC’s STITCH (SmarT Innovations for Technology Connected Health) Institute that creates and investigates advanced wearable devices.

The research, partially funded by the Natural Sciences and Engineering Research Council, was recently published in the Journal of Sensors and Actuators A: Physical.

Here’s a link to and a citation for the paper,

Low-cost ultra-stretchable strain sensors for monitoring human motion and bio-signals by Seyed Reza Larimi, Hojatollah Rezaei Nejad, Michael Oyatsi, Allen O’Brien, Mina Hoorfar, Homayoun Najjaran. Sensors and Actuators A: Physical Volume 271, 1 March 2018, Pages 182-191 [Published online February 2018] https://doi.org/10.1016/j.sna.2018.01.028

This paper is behind a paywall.

Final comments

The term ‘wearable tech’ covers a lot of ground. In addition to sensors, there are materials that harvest energy, detect poisons, etc.  making for a diverse field.

A cheaper way to make artificial organs

In the quest to develop artificial organs, the University of British Columbia (UBC) is the not the first research institution that comes to my mind. It seems I may need to reevaluate now that UBC (Okanagan) has announced some work on bio-inks and artificial organs in a Sept. 12, 2017 news  release (also on EurekAlert) by Patty Wellborn,,

A new bio-ink that may support a more efficient and inexpensive fabrication of human tissues and organs has been created by researchers at UBC’s Okanagan campus.

Keekyoung Kim, an assistant professor at UBC Okanagan’s School of Engineering, says this development can accelerate advances in regenerative medicine.

Using techniques like 3D printing, scientists are creating bio-material products that function alongside living cells. These products are made using a number of biomaterials including gelatin methacrylate (GelMA), a hydrogel that can serve as a building block in bio-printing. This type of bio-material—called bio-ink—are made of living cells, but can be printed and molded into specific organ or tissue shapes.

The UBC team analyzed the physical and biological properties of three different GelMA hydrogels—porcine skin, cold-water fish skin and cold-soluble gelatin. They found that hydrogel made from cold-soluble gelatin (gelatin which dissolves without heat) was by far the best performer and a strong candidate for future 3D organ printing.

“A big drawback of conventional hydrogel is its thermal instability. Even small changes in temperature cause significant changes in its viscosity or thickness,” says Kim. “This makes it problematic for many room temperature bio-fabrication systems, which are compatible with only a narrow range of hydrogel viscosities and which must generate products that are as uniform as possible if they are to function properly.”

Kim’s team created two new hydrogels—one from fish skin, and one from cold-soluble gelatin—and compared their properties to those of porcine skin GelMA. Although fish skin GelMA had some benefits, cold-soluble GelMA was the top overall performer. Not only could it form healthy tissue scaffolds, allowing cells to successfully grow and adhere to it, but it was also thermally stable at room temperature.

The UBC team also demonstrated that cold-soluble GelMA produces consistently uniform droplets at temperatures, thus making it an excellent choice for use in 3D bio-printing.

“We hope this new bio-ink will help researchers create improved artificial organs and lead to the development of better drugs, tissue engineering and regenerative therapies,” Kim says. “The next step is to investigate whether or not cold-soluble GelMA-based tissue scaffolds are can be used long-term both in the laboratory and in real-world transplants.”

Three times cheaper than porcine skin gelatin, cold-soluble gelatin is used primarily in culinary applications.

Here’s a link to and a citation for the paper,

Comparative study of gelatin methacrylate hydrogels from different sources for biofabrication applications by Zongjie Wang, Zhenlin Tian, Fredric Menard, and Keekyoung Kim. Biofabrication, Volume 9, Number 4 Special issue on Bioinks https://doi.org/10.1088/1758-5090/aa83cf Published 21 August 2017

© 2017 IOP Publishing Ltd

This paper is behind a paywall.