From The School of Engineering and Applied Science At The University of Pennsylvania: “Tiny Swimming Robots Can Restructure Materials on a Microscopic Level” 

From The School of Engineering and Applied Science

At

U Penn bloc

The University of Pennsylvania

11.15.22
Melissa Pappas

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The researchers’ microrobots use “physical intelligence” to exert control over nearby objects. By spinning and disrupting the alignment of the liquid crystal surrounding them, the robots can attract smaller particles to their edges, then precisely deposit them.

Controlling microscopic processes is inherently challenging. The everyday tools we use to manipulate matter on the macroscale can’t simply be shrunk down to the size of cell, and even if they could, the physical forces they rely on work differently when their targets are measured in nanometers. But while it’s no easy feat, attaining this type of control would pay enormous dividends: whether it’s transporting drugs to tumors for precise therapies, or making functional materials out of the liquid-suspended building blocks known as colloids, Penn Engineers are working to make these processes faster, safer and more reliable.

One approach for controlling these processes is through the use of microrobots.

We typically think of robots as computerized machines like those on assembly lines or in warehouses, programmed to move cargo and to build complex structures like automobiles and cellphones. However, programming a machine smaller than a microchip presents another kind of challenge. Too small for computerization, robots on this scale need to be designed in a completely different way — and adhere to completely different sets of physical and chemical laws — than their bigger counterparts.

Since they’re too small for their own onboard computers microrobots move about by means of an external magnetic force. And to manipulate equally small cargo, they need to take advantage of the different physical and chemical laws that rule the microscale.

At those sizes, every object is greatly influenced by the molecules surrounding it. Whether they are surrounded by gas, like the ambient atmosphere, or immersed in a liquid, microrobots must be designed to exploit this influence through a concept known as “physical intelligence.”

By understanding the system, the surrounding media and the particles within it, physically intelligent microrobots can perform diverse tasks.

Kathleen Stebe, Richer & Elizabeth Goodwin Professor in Chemical and Biomolecular Engineering and Mechanical Engineering and Applied Mechanics, Tianyi Yao, a former Ph.D. student in her lab, Qi Xing Zhang, a current Ph.D. student, and collaborators in the group of Professor Miha Ravnik at the University of Ljubljana are conducting fundamental research that will lay the groundwork for understanding these small-scale interactions in a colloidal fluid of nematic liquid crystals (NLCs), the fluid that makes up each pixel in a liquid crystal display (LCD) screen.

“Nematic liquid crystals exist as a special phase, a structured fluid that is neither liquid nor solid,” says Stebe. “NLCs consist of elongated molecules that self-align in a configuration that requires the least amount of energy. Think of shaking a pan of rice; the grains all align. When you disturb the nematic alignment by introducing microrobots or colloidal cargo, you get really interesting dynamics that you don’t see in water, for example. It is the physics of NLCs that allow us to investigate these unique interactions.”

In one study, published in Advanced Functional Materials [below], the research team describes a four-armed, magnetically controlled microrobot that can swim, carry cargo and actively restructure particles in this complex fluid.

“We started with a complex shape, which produced complex behaviors,” says Stebe. “Here, the microrobot is being controlled by an external magnetic field and is using its physical intelligence to pick up a microparticle as cargo, then it bats it around as it swims to the textured surface. The grooves in the surface material are the perfect size to attract and hold the particle. In fact, it was that surface design that inspired the design of the four-armed microrobot. We took advantage of the physical shape, surface chemistry and special dynamics of the colloid in NLCs to control it.”

“But, the more we observed these sophisticated functions, the more we didn’t understand,” she adds. “We had to turn back to the fundamentals to actually explain what was going on here.”

How was this robot able to swim? How was it able to hold and move particles? In another study, published in Science Advances [below], the team answered those questions with a microrobot of a simpler shape.

“The disk shape allowed us to better understand the microbot’s swimming ability,” says Stebe. “Here we can see that as one side of the disk tilts upwards, there is a topological defect that is created underneath it. The interaction between the topological defect and the disk itself creates an energy gradient that allows for self-propulsion of the disk.”

The reason for the topological defect which allows for the swimming function of the robot is because of the complex organization of the NLCs, which differs dramatically from disorganized liquids like water.

“Using physics of nematic liquid crystals,” says Yao, the lead author of both studies, “we can build physically intelligent microrobotic systems. We can make long-range interactions, tune binding strengths and reconfigure the space. While we have proven these interactions on the microscale, the prevailing physics are also effective on very small scales, on the order of 30–50 nanometers.”

Being able to manipulate processes on this level is groundbreaking, and understanding how robotic systems are able to perform tasks in an indirect way, considering the fluid dynamics and physical interactions of the media as a part of the microrobot’s design, is key.

Stebe and her team are now able to imagine real-world applications for this technology in the optical device industry as well as many other fields. Smart materials, aware of their environment, may be designed using temperature and light as controls for microrobotic tasks.

“Together with dedicated colleagues and graduate students, we have been working hard on this technology, and are excited to see years of work come to fruition,” she says. “We are now standing on the edge of real applications and ready to explore.”

Science papers:
Advanced Functional Materials
Science Advances
See the science papers for instructive material with images.

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

The School of Engineering and Applied Science is an undergraduate and graduate school of The University of Pennsylvania. The School offers programs that emphasize hands-on study of engineering fundamentals (with an offering of approximately 300 courses) while encouraging students to leverage the educational offerings of the broader University. Engineering students can also take advantage of research opportunities through interactions with Penn’s School of Medicine, School of Arts and Sciences and the Wharton School.

Penn Engineering offers bachelors, masters and Ph.D. degree programs in contemporary fields of engineering study. The nationally ranked bioengineering department offers the School’s most popular undergraduate degree program. The Jerome Fisher Program in Management and Technology, offered in partnership with the Wharton School, allows students to simultaneously earn a Bachelor of Science degree in Economics as well as a Bachelor of Science degree in Engineering. SEAS also offers several masters programs, which include: Executive Master’s in Technology Management, Master of Biotechnology, Master of Computer and Information Technology, Master of Computer and Information Science and a Master of Science in Engineering in Telecommunications and Networking.

History

The study of engineering at The University of Pennsylvania can be traced back to 1850 when the University trustees adopted a resolution providing for a professorship of “Chemistry as Applied to the Arts”. In 1852, the study of engineering was further formalized with the establishment of the School of Mines, Arts and Manufactures. The first Professor of Civil and Mining Engineering was appointed in 1852. The first graduate of the school received his Bachelor of Science degree in 1854. Since that time, the school has grown to six departments. In 1973, the school was renamed as the School of Engineering and Applied Science.

The early growth of the school benefited from the generosity of two Philadelphians: John Henry Towne and Alfred Fitler Moore. Towne, a mechanical engineer and railroad developer, bequeathed the school a gift of $500,000 upon his death in 1875. The main administration building for the school still bears his name. Moore was a successful entrepreneur who made his fortune manufacturing telegraph cable. A 1923 gift from Moore established the Moore School of Electrical Engineering, which is the birthplace of the first electronic general-purpose Turing-complete digital computer, ENIAC, in 1946.

During the latter half of the 20th century the school continued to break new ground. In 1958, Barbara G. Mandell became the first woman to enroll as an undergraduate in the School of Engineering. In 1965, the university acquired two sites that were formerly used as U.S. Army Nike Missile Base (PH 82L and PH 82R) and created the Valley Forge Research Center. In 1976, the Management and Technology Program was created. In 1990, a Bachelor of Applied Science in Biomedical Science and Bachelor of Applied Science in Environmental Science were first offered, followed by a master’s degree in Biotechnology in 1997.

The school continues to expand with the addition of the Melvin and Claire Levine Hall for computer science in 2003, Skirkanich Hall for Bioengineering in 2006, and the Krishna P. Singh Center for Nanotechnology in 2013.

Academics

Penn’s School of Engineering and Applied Science is organized into six departments:

Bioengineering
Chemical and Biomolecular Engineering
Computer and Information Science
Electrical and Systems Engineering
Materials Science and Engineering
Mechanical Engineering and Applied Mechanics

The school’s Department of Bioengineering, originally named Biomedical Electronic Engineering, consistently garners a top-ten ranking at both the undergraduate and graduate level from U.S. News & World Report. The department also houses the George H. Stephenson Foundation Educational Laboratory & Bio-MakerSpace (aka Biomakerspace) for training undergraduate through PhD students. It is Philadelphia’s and Penn’s only Bio-MakerSpace and it is open to the Penn community, encouraging a free flow of ideas, creativity, and entrepreneurship between Bioengineering students and students throughout the university.

Founded in 1893, the Department of Chemical and Biomolecular Engineering is “America’s oldest continuously operating degree-granting program in chemical engineering.”

The Department of Electrical and Systems Engineering is recognized for its research in electroscience, systems science and network systems and telecommunications.

Originally established in 1946 as the School of Metallurgical Engineering, the Materials Science and Engineering Department “includes cutting edge programs in nanoscience and nanotechnology, biomaterials, ceramics, polymers, and metals.”

The Department of Mechanical Engineering and Applied Mechanics draws its roots from the Department of Mechanical and Electrical Engineering, which was established in 1876.

Each department houses one or more degree programs. The Chemical and Biomolecular Engineering, Materials Science and Engineering, and Mechanical Engineering and Applied Mechanics departments each house a single degree program.

Bioengineering houses two programs (both a Bachelor of Science in Engineering degree as well as a Bachelor of Applied Science degree). Electrical and Systems Engineering offers four Bachelor of Science in Engineering programs: Electrical Engineering, Systems Engineering, Computer Engineering, and the Networked & Social Systems Engineering, the latter two of which are co-housed with Computer and Information Science (CIS). The CIS department, like Bioengineering, offers Computer and Information Science programs under both bachelor programs. CIS also houses Digital Media Design, a program jointly operated with PennDesign.

Research

Penn’s School of Engineering and Applied Science is a research institution. SEAS research strives to advance science and engineering and to achieve a positive impact on society.

U Penn campus

Academic life at University of Pennsylvania is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

The University of Pennsylvania is a private Ivy League research university in Philadelphia, Pennsylvania. The university claims a founding date of 1740 and is one of the nine colonial colleges chartered prior to the U.S. Declaration of Independence. Benjamin Franklin, Penn’s founder and first president, advocated an educational program that trained leaders in commerce, government, and public service, similar to a modern liberal arts curriculum.

Penn has four undergraduate schools as well as twelve graduate and professional schools. Schools enrolling undergraduates include the College of Arts and Sciences; the School of Engineering and Applied Science; the Wharton School; and the School of Nursing. Penn’s “One University Policy” allows students to enroll in classes in any of Penn’s twelve schools. Among its highly ranked graduate and professional schools are a law school whose first professor wrote the first draft of the United States Constitution, the first school of medicine in North America (Perelman School of Medicine, 1765), and the first collegiate business school (Wharton School, 1881).

Penn is also home to the first “student union” building and organization (Houston Hall, 1896), the first Catholic student club in North America (Newman Center, 1893), the first double-decker college football stadium (Franklin Field, 1924 when second deck was constructed), and Morris Arboretum, the official arboretum of the Commonwealth of Pennsylvania. The first general-purpose electronic computer (ENIAC) was developed at Penn and formally dedicated in 1946. In 2019, the university had an endowment of $14.65 billion, the sixth-largest endowment of all universities in the United States, as well as a research budget of $1.02 billion. The university’s athletics program, the Quakers, fields varsity teams in 33 sports as a member of the NCAA Division I Ivy League conference.

As of 2018, distinguished alumni and/or Trustees include three U.S. Supreme Court justices; 32 U.S. senators; 46 U.S. governors; 163 members of the U.S. House of Representatives; eight signers of the Declaration of Independence and seven signers of the U.S. Constitution (four of whom signed both representing two-thirds of the six people who signed both); 24 members of the Continental Congress; 14 foreign heads of state and two presidents of the United States, including Donald Trump. As of October 2019, 36 Nobel laureates; 80 members of the American Academy of Arts and Sciences; 64 billionaires; 29 Rhodes Scholars; 15 Marshall Scholars and 16 Pulitzer Prize winners have been affiliated with the university.

History

The University of Pennsylvania considers itself the fourth-oldest institution of higher education in the United States, though this is contested by Princeton University and Columbia University. The university also considers itself as the first university in the United States with both undergraduate and graduate studies.

In 1740, a group of Philadelphians joined together to erect a great preaching hall for the traveling evangelist George Whitefield, who toured the American colonies delivering open-air sermons. The building was designed and built by Edmund Woolley and was the largest building in the city at the time, drawing thousands of people the first time it was preached in. It was initially planned to serve as a charity school as well, but a lack of funds forced plans for the chapel and school to be suspended. According to Franklin’s autobiography, it was in 1743 when he first had the idea to establish an academy, “thinking the Rev. Richard Peters a fit person to superintend such an institution”. However, Peters declined a casual inquiry from Franklin and nothing further was done for another six years. In the fall of 1749, now more eager to create a school to educate future generations, Benjamin Franklin circulated a pamphlet titled Proposals Relating to the Education of Youth in Pensilvania, his vision for what he called a “Public Academy of Philadelphia”. Unlike the other colonial colleges that existed in 1749—Harvard University, William & Mary, Yale Unversity, and The College of New Jersey—Franklin’s new school would not focus merely on education for the clergy. He advocated an innovative concept of higher education, one which would teach both the ornamental knowledge of the arts and the practical skills necessary for making a living and doing public service. The proposed program of study could have become the nation’s first modern liberal arts curriculum, although it was never implemented because Anglican priest William Smith (1727-1803), who became the first provost, and other trustees strongly preferred the traditional curriculum.

Franklin assembled a board of trustees from among the leading citizens of Philadelphia, the first such non-sectarian board in America. At the first meeting of the 24 members of the board of trustees on November 13, 1749, the issue of where to locate the school was a prime concern. Although a lot across Sixth Street from the old Pennsylvania State House (later renamed and famously known since 1776 as “Independence Hall”), was offered without cost by James Logan, its owner, the trustees realized that the building erected in 1740, which was still vacant, would be an even better site. The original sponsors of the dormant building still owed considerable construction debts and asked Franklin’s group to assume their debts and, accordingly, their inactive trusts. On February 1, 1750, the new board took over the building and trusts of the old board. On August 13, 1751, the “Academy of Philadelphia”, using the great hall at 4th and Arch Streets, took in its first secondary students. A charity school also was chartered on July 13, 1753 by the intentions of the original “New Building” donors, although it lasted only a few years. On June 16, 1755, the “College of Philadelphia” was chartered, paving the way for the addition of undergraduate instruction. All three schools shared the same board of trustees and were considered to be part of the same institution. The first commencement exercises were held on May 17, 1757.

The institution of higher learning was known as the College of Philadelphia from 1755 to 1779. In 1779, not trusting then-provost the Reverend William Smith’s “Loyalist” tendencies, the revolutionary State Legislature created a University of the State of Pennsylvania. The result was a schism, with Smith continuing to operate an attenuated version of the College of Philadelphia. In 1791, the legislature issued a new charter, merging the two institutions into a new University of Pennsylvania with twelve men from each institution on the new board of trustees.

Penn has three claims to being the first university in the United States, according to university archives director Mark Frazier Lloyd: the 1765 founding of the first medical school in America made Penn the first institution to offer both “undergraduate” and professional education; the 1779 charter made it the first American institution of higher learning to take the name of “University”; and existing colleges were established as seminaries (although, as detailed earlier, Penn adopted a traditional seminary curriculum as well).

After being located in downtown Philadelphia for more than a century, the campus was moved across the Schuylkill River to property purchased from the Blockley Almshouse in West Philadelphia in 1872, where it has since remained in an area now known as University City. Although Penn began operating as an academy or secondary school in 1751 and obtained its collegiate charter in 1755, it initially designated 1750 as its founding date; this is the year that appears on the first iteration of the university seal. Sometime later in its early history, Penn began to consider 1749 as its founding date and this year was referenced for over a century, including at the centennial celebration in 1849. In 1899, the board of trustees voted to adjust the founding date earlier again, this time to 1740, the date of “the creation of the earliest of the many educational trusts the University has taken upon itself”. The board of trustees voted in response to a three-year campaign by Penn’s General Alumni Society to retroactively revise the university’s founding date to appear older than Princeton University, which had been chartered in 1746.

Research, innovations and discoveries

Penn is classified as an “R1” doctoral university: “Highest research activity.” Its economic impact on the Commonwealth of Pennsylvania for 2015 amounted to $14.3 billion. Penn’s research expenditures in the 2018 fiscal year were $1.442 billion, the fourth largest in the U.S. In fiscal year 2019 Penn received $582.3 million in funding from the National Institutes of Health.

In line with its well-known interdisciplinary tradition, Penn’s research centers often span two or more disciplines. In the 2010–2011 academic year alone, five interdisciplinary research centers were created or substantially expanded; these include the Center for Health-care Financing; the Center for Global Women’s Health at the Nursing School; the $13 million Morris Arboretum’s Horticulture Center; the $15 million Jay H. Baker Retailing Center at Wharton; and the $13 million Translational Research Center at Penn Medicine. With these additions, Penn now counts 165 research centers hosting a research community of over 4,300 faculty and over 1,100 postdoctoral fellows, 5,500 academic support staff and graduate student trainees. To further assist the advancement of interdisciplinary research President Amy Gutmann established the “Penn Integrates Knowledge” title awarded to selected Penn professors “whose research and teaching exemplify the integration of knowledge”. These professors hold endowed professorships and joint appointments between Penn’s schools.

Penn is also among the most prolific producers of doctoral students. With 487 PhDs awarded in 2009, Penn ranks third in the Ivy League, only behind Columbia University and Cornell University (Harvard University did not report data). It also has one of the highest numbers of post-doctoral appointees (933 in number for 2004–2007), ranking third in the Ivy League (behind Harvard and Yale University) and tenth nationally.

In most disciplines Penn professors’ productivity is among the highest in the nation and first in the fields of epidemiology, business, communication studies, comparative literature, languages, information science, criminal justice and criminology, social sciences and sociology. According to the National Research Council nearly three-quarters of Penn’s 41 assessed programs were placed in ranges including the top 10 rankings in their fields, with more than half of these in ranges including the top five rankings in these fields.

Penn’s research tradition has historically been complemented by innovations that shaped higher education. In addition to establishing the first medical school; the first university teaching hospital; the first business school; and the first student union Penn was also the cradle of other significant developments. In 1852, Penn Law was the first law school in the nation to publish a law journal still in existence (then called The American Law Register, now the Penn Law Review, one of the most cited law journals in the world). Under the deanship of William Draper Lewis, the law school was also one of the first schools to emphasize legal teaching by full-time professors instead of practitioners, a system that is still followed today. The Wharton School was home to several pioneering developments in business education. It established the first research center in a business school in 1921 and the first center for entrepreneurship center in 1973 and it regularly introduced novel curricula for which BusinessWeek wrote, “Wharton is on the crest of a wave of reinvention and change in management education”.

Several major scientific discoveries have also taken place at Penn. The university is probably best known as the place where the first general-purpose electronic computer (ENIAC) was born in 1946 at the Moore School of Electrical Engineering.

ENIAC UPenn

It was here also where the world’s first spelling and grammar checkers were created, as well as the popular COBOL programming language. Penn can also boast some of the most important discoveries in the field of medicine. The dialysis machine used as an artificial replacement for lost kidney function was conceived and devised out of a pressure cooker by William Inouye while he was still a student at Penn Med; the Rubella and Hepatitis B vaccines were developed at Penn; the discovery of cancer’s link with genes; cognitive therapy; Retin-A (the cream used to treat acne), Resistin; the Philadelphia gene (linked to chronic myelogenous leukemia) and the technology behind PET Scans were all discovered by Penn Med researchers. More recent gene research has led to the discovery of the genes for fragile X syndrome, the most common form of inherited mental retardation; spinal and bulbar muscular atrophy, a disorder marked by progressive muscle wasting; and Charcot–Marie–Tooth disease, a progressive neurodegenerative disease that affects the hands, feet and limbs.

Conductive polymer was also developed at Penn by Alan J. Heeger, Alan MacDiarmid and Hideki Shirakawa, an invention that earned them the Nobel Prize in Chemistry. On faculty since 1965, Ralph L. Brinster developed the scientific basis for in vitro fertilization and the transgenic mouse at Penn and was awarded the National Medal of Science in 2010. The theory of superconductivity was also partly developed at Penn, by then-faculty member John Robert Schrieffer (along with John Bardeen and Leon Cooper). The university has also contributed major advancements in the fields of economics and management. Among the many discoveries are conjoint analysis, widely used as a predictive tool especially in market research; Simon Kuznets’s method of measuring Gross National Product; the Penn effect (the observation that consumer price levels in richer countries are systematically higher than in poorer ones) and the “Wharton Model” developed by Nobel-laureate Lawrence Klein to measure and forecast economic activity. The idea behind Health Maintenance Organizations also belonged to Penn professor Robert Eilers, who put it into practice during then-President Nixon’s health reform in the 1970s.

International partnerships

Students can study abroad for a semester or a year at partner institutions such as the London School of Economics(UK), University of Barcelona [Universitat de Barcelona](ES), Paris Institute of Political Studies [Institut d’études politiques de Paris](FR), University of Queensland(AU), University College London(UK), King’s College London(UK), Hebrew University of Jerusalem(IL) and University of Warwick(UK).