Tag Archives: Xi Liu

Harvesting the heart’s kinetic energy to power implants

This work comes from Dartmouth College, an educational institution based on the US east coast in the state of New Hampshire. I hardly ever stumble across research from Dartmouth and I assume that’s because they usually focus their interests in areas that are not of direct interest to me,

Rendering of the two designs of the cardiac energy harvesting device. (Cover art by Patricio Sarzosa) Courtesy: Dartmouth College

For a change, we have a point of connection (harvesting biokinetic energy) according to a February 4, 2019 news item on ScienceDaily,

The heart’s motion is so powerful that it can recharge devices that save our lives, according to new research from Dartmouth College.

Using a dime-sized invention developed by engineers at the Thayer School of Engineering at Dartmouth, the kinetic energy of the heart can be converted into electricity to power a wide-range of implantable devices, according to the study funded by the National Institutes of Health.

A February 4, 2019 Dartmouth College news release, which originated the news item, describes the problem and the proposed solution,

Millions of people rely on pacemakers, defibrillators and other live-saving implantable devices powered by batteries that need to be replaced every five to 10 years. Those replacements require surgery which can be costly and create the possibility of complications and infections.

“We’re trying to solve the ultimate problem for any implantable biomedical device,” says Dartmouth engineering professor John X.J. Zhang, a lead researcher on the study his team completed alongside clinicians at the University of Texas in San Antonio. “How do you create an effective energy source so the device will do its job during the entire life span of the patient, without the need for surgery to replace the battery?”

“Of equal importance is that the device not interfere with the body’s function,” adds Dartmouth research associate Lin Dong, first author on the paper. “We knew it had to be biocompatible, lightweight, flexible, and low profile, so it not only fits into the current pacemaker structure but is also scalable for future multi-functionality.”

The team’s work proposes modifying pacemakers to harness the kinetic energy of the lead wire that’s attached to the heart, converting it into electricity to continually charge the batteries. The added material is a type of thin polymer piezoelectric film called “PVDF” and, when designed with porous structures — either an array of small buckle beams or a flexible cantilever — it can convert even small mechanical motion to electricity. An added benefit: the same modules could potentially be used as sensors to enable data collection for real-time monitoring of patients.

The results of the three-year study, completed by Dartmouth’s engineering researchers along with clinicians at UT Health San Antonio, were just published in the cover story for Advanced Materials Technologies.

The two remaining years of NIH funding plus time to finish the pre-clinical process and obtain regulatory approval puts a self-charging pacemaker approximately five years out from commercialization, according to Zhang

“We’ve completed the first round of animal studies with great results which will be published soon,” says Zhang. “There is already a lot of expressed interest from the major medical technology companies, and Andrew Closson, one of the study’s authors working with Lin Dong and an engineering PhD Innovation Program student at Dartmouth, is learning the business and technology transfer skills to be a cohort in moving forward with the entrepreneurial phase of this effort.”

Other key collaborators on the study include Dartmouth engineering professor Zi Chen, an expert on thin structure mechanics, and Dr. Marc Feldman, professor and clinical cardiologist at UT [University of Texas] Health San Antonio.

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

Energy Harvesting: Flexible Porous Piezoelectric Cantilever on a Pacemaker Lead for Compact Energy Harvesting by Lin Dong, Xiaomin Han, Zhe Xu, Andrew B. Closson, Yin Liu, Chunsheng Wen, Xi Liu, Gladys Patricia Escobar, Meagan Oglesby, Marc Feldman, Zi Chen, John X. J. Zhang. Adv. Mater. Technol. 1/2019 https://doi.org/10.1002/admt.201970002 First published: 08 January 2019

This paper is open access.

Brain-friendly interface to replace neural prosthetics one day?

This research will not find itself occupying anyone’s brain for some time to come but it is interesting to find out that neural prosthetics have some drawbacks and there is work being done to address them. From an Aug. 10, 2015 news item on Azonano,

Instead of using neural prosthetic devices–which suffer from immune-system rejection and are believed to fail due to a material and mechanical mismatch–a multi-institutional team, including Lohitash Karumbaiah of the University of Georgia’s Regenerative Bioscience Center, has developed a brain-friendly extracellular matrix environment of neuronal cells that contain very little foreign material. These by-design electrodes are shielded by a covering that the brain recognizes as part of its own composition.

An Aug. 5, 2015 University of Georgia news release, which originated the news item, describes the new approach and technique in more detail,

Although once believed to be devoid of immune cells and therefore of immune responses, the brain is now recognized to have its own immune system that protects it against foreign invaders.

“This is not by any means the device that you’re going to implant into a patient,” said Karumbaiah, an assistant professor of animal and dairy science in the UGA College of Agricultural and Environmental Sciences. “This is proof of concept that extracellular matrix can be used to ensheathe a functioning electrode without the use of any other foreign or synthetic materials.”

Implantable neural prosthetic devices in the brain have been around for almost two decades, helping people living with limb loss and spinal cord injury become more independent. However, not only do neural prosthetic devices suffer from immune-system rejection, but most are believed to eventually fail because of a mismatch between the soft brain tissue and the rigid devices.

The collaboration, led by Wen Shen and Mark Allen of the University of Pennsylvania, found that the extracellular matrix derived electrodes adapted to the mechanical properties of brain tissue and were capable of acquiring neural recordings from the brain cortex.

“Neural interface technology is literally mind boggling, considering that one might someday control a prosthetic limb with one’s own thoughts,” Karumbaiah said.

The study’s joint collaborators were Ravi Bellamkonda, who conceived the new approach and is chair of the Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University, as well as Allen, who at the time was director of the Institute for Electronics and Nanotechnology.

“Hopefully, once we converge upon the nanofabrication techniques that would enable these to be clinically translational, this same methodology could then be applied in getting these extracellular matrix derived electrodes to be the next wave of brain implants,” Karumbaiah said.

Currently, one out of every 190 Americans is living with limb loss, according to the National Institutes of Health. There is a significant burden in cost of care and quality of life for people suffering from this disability.

The research team is one part of many in the prosthesis industry, which includes those who design the robotics for the artificial limbs, others who make the neural prosthetic devices and developers who design the software that decodes the neural signal.

“What neural prosthetic devices do is communicate seamlessly to an external prosthesis,” Karumbaiah said, “providing independence of function without having to have a person or a facility dedicated to their care.”

Karumbaiah hopes further collaboration will allow them to make positive changes in the industry, saying that, “it’s the researcher-to-industry kind of conversation that now needs to take place, where companies need to come in and ask: ‘What have you learned? How are the devices deficient, and how can we make them better?'”

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

Extracellular matrix-based intracortical microelectrodes: Toward a microfabricated neural interface based on natural materials by Wen Shen, Lohitash Karumbaiah, Xi Liu, Tarun Saxena, Shuodan Chen, Radhika Patkar, Ravi V. Bellamkonda, & Mark G. Allen. Microsystems & Nanoengineering 1, Article number: 15010 (2015) doi:10.1038/micronano.2015.10

This appears to be an open access paper.

One final note, I have written frequently about prosthetics and neural prosthetics, which you can find by using either of those terms and/or human enhancement. Here’s my latest piece, a March 25, 2015 posting.