Pacemakers are lifesaving devices that regulate the heartbeats of people with chronic heart diseases like atrial fibrillation and other forms of arrhythmia. However, pacemaker implantation is an invasive procedure, and the lifesaving pacing the devices provide can be extremely painful. Additionally, pacemakers can only be used to treat a few specific types of disease.

In a paper published Wednesday in Science Advances, a University of Arizona-led team of researchers detail the workings of a wireless, battery-free pacemaker they designed that could be implanted with a less invasive procedure than currently possible and would cause patients less pain. The study was helmed by researchers in the Gutruf Lab, led by biomedical engineering assistant professor and Craig M. Berge Faculty Fellow Philipp Gutruf.

Currently available pacemakers work by implanting one or two leads, or points of contact, into the heart with hooks or screws. If the sensors on these leads detect a dangerous irregularity, they send an electrical shock through the heart to reset the beat.

“All of the cells inside the heart get hit at one time, including the pain receptors, and that’s what makes pacing or defibrillation painful,” Gutruf said. “It affects the heart muscle as a whole.”

The device Gutruf’s team has developed, which has not yet been tested in humans, would allow pacemakers to send much more targeted signals using a new digitally manufactured mesh design that encompasses the entire heart. The device uses light and a technique called optogenetics.

Optogenetics modifies cells, usually neurons, sensitive to light, then uses light to affect the behavior of those cells. This technique only targets cardiomyocytes, the cells of the muscle that trigger contraction and make up the beat of the heart. This precision will not only reduce pain for pacemaker patients by bypassing the heart’s pain receptors, it will also allow the pacemaker to respond to different kinds of irregularities in more appropriate ways. For example, during atrial fibrillation, the upper and lower chambers of the heart beat asynchronously, and a pacemaker’s role is to get the two parts back in line.

“Whereas right now, we have to shock the whole heart to do this, these new devices can do much more precise targeting, making defibrillation both more effective and less painful,” said Igor Efimov, professor of biomedical engineering and medicine at Northwestern University, where the devices were lab-tested. “This technology could make life easier for patients all over the world, while also helping scientists and physicians learn more about how to monitor and treat the disease.”

Flexible mesh encompasses the heart

To ensure the light signals can reach many different parts of the heart, the team created a design that involves encompassing the organ, rather than implanting leads that provide limited points of contact.

The new pacemaker model consists of four petallike structures made of thin, flexible film, which contain light sources and a recording electrode. The petals, specially designed to accommodate the way the heart changes shape as it beats, fold up around the sides of the organ to envelop it, like a flower closing up at night.

“Current pacemakers record basically a simple threshold, and they will tell you, ‘This is going into arrhythmia, now shock!'” Gutruf said. “But this device has a computer on board where you can input different algorithms that allow you to pace in a more sophisticated way. It’s made for research.”

Because the system uses light to affect the heart, rather than electrical signals, the device can continue recording information even when the pacemaker needs to defibrillate. In current pacemakers, the electrical signal from the defibrillation can interfere with recording capabilities, leaving physicians with an incomplete picture of cardiac episodes. Additionally, the device does not require a battery, which could save pacemaker patients from needing to replace the battery in their device every five to seven years, as is currently the norm.

Gutruf’s team collaborated with researchers at Northwestern University on the project. While the current version of the device has been successfully demonstrated in animal models, the researchers look forward to furthering their work, which could improve the quality of life for millions of people.

There is evidence that lower-income and people of color (POC) in the U.S. do not use bike share as much as higher-income and white people. Using data from residents living near bike share stations in New York, Chicago, and Philadelphia, the paper examines reasons for these disparities. Researchers looked at many factors that might explain bike share use and interest in lower-income, racially diverse, traditionally underserved neighborhoods. They focused on residents who live near bike share stations, so that proximity would not be a barrier.

A few key findings:

1. People who are not members, but are interested in using bike share, including POC, are motivated to use bike share for fun, recreation, and social reasons (as opposed to utility).
2. Knowledge of bike share and receiving information from interactive sources (for example, bike share ambassadors) are associated with bike share use.
3. Cost is a barrier for people who are interested in using bike share, but are not members. Discounted memberships are one solution, but survey results indicate that many people do know know about them.

Some reasons for not using bike share among people of color and lower-income people may also be related to reasons for not bicycling, generally. These include concerns about traffic safety as well as personal safety.

This paper is an analysis of data collected in a “Breaking Barriers to Bike Share” project funded by the National Institute for Transportation and Communities (NITC) and the Better Bike Share Partnership (BBSP). Read more about the original study and explore some of the products to come out of this research, including a set of ten bike share equity briefs to help operators establish equity programs based on what’s been shown to work.

Portland State University’s Transportation Research and Education Center (TREC) is home to the U.S. DOT funded National Institute for Transportation and Communities (NITC), the Initiative for Bicycle and Pedestrian Innovation (IBPI), PORTAL, BikePed Portal and other transportation grants and programs. We produce impactful research and tools for transportation decision makers, expand the diversity and capacity of the workforce, and engage students and professionals through education and participation in research.

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NASA’s InSight lander recorded a magnitude 4 marsquake last Dec. 24, but scientists learned only later the cause of that quake: a meteoroid strike estimated to be one of the biggest seen on Mars since NASA began exploring the cosmos. What’s more, the meteoroid excavated boulder-size chunks of ice buried closer to the Martian equator than ever found before — a discovery with implications for NASA’s future plans to send astronauts to the Red Planet.

Scientists determined the quake resulted from a meteoroid impact when they looked at before-and-after images from NASA’s Mars Reconnaissance Orbiter (MRO) and spotted a new, yawning crater. Offering a rare opportunity to see how a large impact shook the ground on Mars, the event and its effects are detailed in two papers published Thursday, Oct. 27, in the journal Science.

The meteoroid is estimated to have spanned 16 to 39 feet (5 to 12 meters) — small enough that it would have burned up in Earth’s atmosphere, but not in Mars’ thin atmosphere, which is just 1% as dense as our planet’s. The impact, in a region called Amazonis Planitia, blasted a crater roughly 492 feet (150 meters) across and 70 feet (21 meters) deep. Some of the ejecta thrown by the impact flew as far as 23 miles (37 kilometers) away.

With images and seismic data documenting the event, this is believed to be one of the largest craters ever witnessed forming any place in the solar system. Many larger craters exist on the Red Planet, but they are significantly older and predate any Mars mission.

“It’s unprecedented to find a fresh impact of this size,” said Ingrid Daubar of Brown University, who leads InSight’s Impact Science Working Group. “It’s an exciting moment in geologic history, and we got to witness it.”

InSight has seen its power drastically decline in recent months due to dust settling on its solar panels. The spacecraft now is expected to shut down within the next six weeks, bringing the mission’s science to an end.

InSight is studying the planet’s crust, mantle, and core. Seismic waves are key to the mission and have revealed the size, depth, and composition of Mars’ inner layers. Since landing in November 2018, InSight has detected 1,318 marsquakes, including several caused by smaller meteoroid impacts.

But the quake resulting from last December’s impact was the first observed to have surface waves — a kind of seismic wave that ripples along the top of a planet’s crust. The second of the two Science papers related to the big impact describes how scientists use these waves to study the structure of Mars’ crust.

Crater Hunters

In late 2021, InSight scientists reported to the rest of the team they had detected a major marsquake on Dec. 24. The crater was first spotted on Feb. 11, 2022, by scientists working at Malin Space Science Systems (MSSS), which built and operates two cameras aboard MRO. The Context Camera (CTX) provides black-and-white, medium-resolution images, while the Mars Color Imager (MARCI) produces daily maps of the entire planet, allowing scientists to track large-scale weather changes like the recent regional dust storm that further diminished InSight’s solar power.

The impact’s blast zone was visible in MARCI data that allowed the team to pin down a 24-hour period within which the impact occurred. These observations correlated with the seismic epicenter, conclusively demonstrating that a meteoroid impact caused the large Dec. 24 marsquake.

“The image of the impact was unlike any I had seen before, with the massive crater, the exposed ice, and the dramatic blast zone preserved in the Martian dust,” said Liliya Posiolova, who leads the Orbital Science and Operations Group at MSSS. “I couldn’t help but imagine what it must have been like to witness the impact, the atmospheric blast, and debris ejected miles downrange.”

Establishing the rate at which craters appear on Mars is critical for refining the planet’s geologic timeline. On older surfaces, such as those of Mars and our Moon, there are more craters than on Earth; on our planet, the processes of erosion and plate tectonics erase older features from the surface.

New craters also expose materials below the surface. In this case, large chunks of ice scattered by the impact were viewed by MRO’s High-Resolution Imaging Science Experiment (HiRISE) color camera.

Subsurface ice will be a vital resource for astronauts, who could use it for a variety of needs, including drinking water, agriculture, and rocket propellant. Buried ice has never been spotted this close to the Martian equator, which, as the warmest part of Mars, is an appealing location for astronauts.

More About the Missions

JPL manages InSight and the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the Mars Reconnaissance Orbiter, InSight spacecraft (including its cruise stage and lander), and supports spacecraft operations for both missions.

Malin Space Science Systems in San Diego built and operates the Context Camera and MARCI camera. University of Arizona built and operates the HiRISE camera.

A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors, and the Italian Space Agency (ASI) supplied a passive laser retroreflector.