Just wanted to drop some interesting research to read during the Thanksgiving weekend - in-between football games and leftover turkey and stuffing sandwiches. Medical advancements continue and this weekend we look at wrapping a pacemaker in cellulose and how VR and haptics deliver feeling. Hope your Thanksgiving was great!
Protection for pacemakers
ETH scientists have developed a special protective membrane made of cellulose that significantly reduces the build-up of fibrotic tissue around cardiac pacemaker implants, which could greatly simplify surgical procedures for patients with cardiac pacemakers.
“Every pacemaker has to be replaced at some point. When this time comes, typically after about five years when the device’s battery expires, the patient has to undergo surgery,” explains Aldo Ferrari, senior scientist in ETH Professor Dimos Poulikakos’s group and at Empa. “If too much fibrotic tissue has formed around the pacemaker, it complicates the procedure,” he explains. In such cases, the surgeon has to cut into and remove this excess tissue. Not only does that prolong the operation, it also increases the risk of complications such as infection.
Microstructure reduces fibrotic tissue formation
To overcome this issue, Ferrari and his colleagues at ETH Zurich spent the last few years developing a membrane with a special surface structure that is less conducive to the growth of fibrotic tissue than the smooth metal surface of pacemakers. This membrane has now been patented and Ferrari is working with fellow researchers at the Wyss Zurich research center, the University of Zurich, and the German Center of Cardiovascular Research in Berlin to make it market-ready for use in patients.
As part of this process, the research consortium has now tested the membrane on pigs. In each pig, the scientists implanted two pacemakers, one of which was enveloped in the cellulose membrane.
Following the one-year test period, the researchers can report positive results: the pigs’ bodies tolerate the membrane and do not reject it.
“This is an important finding because tolerance is a core requirement for implant materials,” Ferrari says.
Just as importantly, the membrane did what it was supposed to: the fibrotic tissue that formed around it was, on average, only a third as thick as the tissue that formed around the unencapsulated pacemakers.
Next step: Clinical trials
The scientists attribute this reduction in fibrotic tissue formation in the first stage to the material itself – cellulose is fibrous by nature.
“When fibrotic tissue forms, the first stage is the deposition of proteins on the surface. A fibrous membrane surface impedes this process,” explains Francesco Robotti, lead author of the study and a scientist in ETH Professor Poulikakos’s group.
Another factor is that the researchers created the membrane with honeycomb-like indentations in the surface, each measuring 10 micrometers in diameter.
“These indentations make it difficult for the cells that form fibrotic tissue to adhere to the surface – the second stage in the formation processes,” Robotti says.
Now that the material has proved successful in animal trials, the scientists plan to apply for approval for clinical trials in humans in partnership with the ETH spin-off Hylomorph, which will be responsible for commercialization of the membrane. The trials are slated to start next year at three large cardiac centers in Germany.
This work was carried out as part of University Medicine Zurich’s Zurich Heart project and ETH+ project ETHeart.
Epidermal VR gives technology a human touch
Northwestern University researchers have developed a new thin, wireless system that adds a sense of touch to any virtual reality (VR) experience. Not only does this platform potentially add new dimensions to our long-distance relationships and entertainment, the technology also provides prosthetics with sensory feedback and imparts telemedicine with a human touch.
Referred to as an epidermal VR system, the device communicates touch through a fast, programmable array of miniature vibrating actuators embedded into a thin, soft, flexible material. The 15cm x 15cm sheet-like prototypes comfortably laminate onto the curved surfaces of the skin without bulky batteries and cumbersome wires.
“People have contemplated this overall concept in the past, but without a clear basis for a realistic technology with the right set of characteristics or the proper form of scalability. Past designs involve manual assemblies of actuators, wires, batteries and combined internal and external control hardware,” says Northwestern’s John A. Rogers, a bioelectronics pioneer. “We leveraged our knowledge in stretchable electronics and wireless power transfer to put together a superior collection of components, including miniaturized actuators, in an advanced architecture designed as a skin-interfaced wearable device - with almost no encumbrances on the user. We feel that it’s a good starting point that will scale naturally to full-body systems and hundreds or thousands of discrete, programmable actuators.”
“We are expanding the boundaries and capabilities of virtual and augmented reality,” says Northwestern’s Yonggang Huang, who co-led the research with Rogers. “By comparison to the eyes and the ears, the skin is a relatively underexplored sensory interface that could significantly enhance experiences.”
Rogers and Huang’s most sophisticated device incorporates a distributed array of 32 individually programmable, millimeter-scale actuators, each of which generates a discrete sense of touch at a corresponding location on the skin. Each actuator resonates most strongly at 200 cycles per second, where the skin exhibits maximum sensitivity.
“We can adjust the frequency and amplitude of each actuator quickly and on-the-fly through our graphical user interface,” Rogers says. “We tailored the designs to maximize the sensory perception of the vibratory force delivered to the skin.”
The patch wirelessly connects to a touchscreen interface (on a smartphone or tablet). When a user touches the touchscreen, that pattern of touch transmits to the patch. If the user draws an “X” pattern on the touchscreen, for example, the devices produce a sensory pattern, simultaneously and in real-time, in the shape of an “X” through the vibratory interface to the skin.
When video chatting from different locations, friends and family members can reach out and virtually touch each other – with negligible time delay and with pressures and patterns that can be controlled through the touchscreen interface.
“You could imagine that sensing virtual touch while on a video call with your family may become ubiquitous in the foreseeable future,” Huang says.
The actuators are embedded into an intrinsically soft and slightly tacky silicone polymer that adheres to the skin without tape or straps. Wireless and battery-free, the device communicates through near-field communication (NFC) protocols, the same technology used in smart phones for electronic payments.