North Oaks, MN - Benjamin Y. H. Liu

PROFESSOR, INVENTOR, ENTREPRENEUR

Loving husband, father, grandfather, and friend

Dr. Benjamin Young-Hwai Liu, Regents Professor at the University of Minnesota, entrepreneurial inventor, and the founder of MSP Corporation, died peacefully at Waverly Gardens Memory Care (North Oaks, MN) on June 30, 2025, at the age of 90.

Professor Liu was born in Shanghai, China, in 1934, during a period of war and turmoil, and as a result, his family moved around China several times. He attended pre-school in Hong Kong, primary school in Shanghai, junior high in Lanchou, senior high in Hong Kong, and college in Taiwan. Because of this constant movement, he did not complete any of the schools he attended in China, and his first degree was a BS in mechanical engineering from the University of Nebraska in Lincoln, Nebraska, in 1956. Subsequently, attracted by his college sweetheart, Helen, whom he met at the National Taiwan University and who was a graduate student studying English literature at the University of Minnesota, he decided to pursue graduate studies at the University of Minnesota. He completed his Ph.D. in Mechanical Engineering with Professor Richard C. Jordan in 1960. Subsequently, at the urging of Professor Jordan, Liu joined the faculty of Mechanical Engineering in 1960 and began a distinguished career in Minnesota over six decades. He was promoted to full professor in 1970. He received a Guggenheim Fellow award and served as Visiting Professor at the University of Paris in 1968. In addition, he was a Fellow of the American Associate for the Advancement of Science, a Fellow of the American Society of Mechanical Engineers, and an elected member of the National Academy of Engineering, one of the highest honors for an engineer in the United States.

Liu made significant and novel contributions to several scientific fields, including solar energy utilization, fundamentals of aerosol behavior, and instruments and techniques for aerosol generation, measurement, sampling and analysis. In total, he published approximately 400 peer-reviewed research papers, four edited books, and mentored thirty-six Ph.D. students. He held over 288 U.S. and foreign patents. His Ph.D. thesis and the published papers on "The Characteristics of Solar Radiation and the Performance of Flat-Plate Solar Energy Collectors" were among the most widely cited publications on the subject, even forty years later. However, he is perhaps best known for pioneering a large number of techniques in aerosol research; he made seminal contributions to aerosol sampling and transport, charging and precipitation, inertial impaction and filtration, and laminar and turbulent deposition. He invented devices that could identify and measure particles 100,000 times smaller than a strand of human hair. Over his career, he developed and refined several aerosol instruments and experimental methods that remain the workhorses in measuring airborne particles.

These inventions have a wide range of applications and they have affected a number of different industries. During Liu's career, his measurement systems and approaches led to standard methods of particle size measurements for pharmaceutical inhalers, and improvement of the yield of semiconductors. Liu was a part of a team developing a device that examined the type and amount of dust found in spacecrafts, particularly for the shuttle Columbia at NASA. He was also a key expert consultant in tobacco litigation cases. He currently has a patent for paint spray analysis, to help maximize the effectiveness in paint sprayer applications. Environmentally, the applications of Liu's research on airborne particles have been particularly far reaching from air quality in coal mines, to industrial clean rooms, from yellow clouds suspended over the LA urban area to wildlife refuges in the depths of the Grand Canyon. His wide-range particles spectrometers, measuring particles as small as 10 nanometers, were used in Beijing to help monitor air pollution during the Beijing Olympics.

Liu was the second director of the world-renowned Particle Technology Laboratory at the University of Minnesota from 1973-95, succeeding the founding director, Professor Kenneth T. Whitby.

Expanding beyond atmospheric research, Liu promoted industry-university collaborations by organizing two industrial consortia at the University, the Microcontamination Research Consortium (MRC) and the Center for Filtration Research (CFR). MRC was founded, with co-Director Professor David Y.H. Pui, in 1985 with 17 national and international companies in the semiconductor industry. A total of 36 graduate students, including 25 Ph.D.s, completed the program, and 75% of the graduates are working in microelectronics companies. The CFR was co-founded with Professor Pui in 1991. It started with 4 companies and has now increased to 18 companies. Many graduates from these two programs are now serving in leadership positions in these companies. In 1978, Liu and Pui started the Aerosol and Particle Measurement Short Course for the continuing education of industrial, governmental, and university personnel. The Short Course is now in its 46th year and has been attended by more than 2,600 people.

In addition to his research contributions, Liu was a founding father of the aerosol research community in the United States. He was a founder of the American Association for Aerosol Research (AAAR) in 1982, a founding editor-in-chief of the journal Aerosol Science and Technology (1982-93), and a Board Member (1982-84), Vice President (1984-85), and President (1986-88) of AAAR.

The Benjamin Y.H. Liu award was established in 2002 by AAAR to honor outstanding contributions to the development of aerosol instrumentation and experimental aerosol techniques. Together with his colleagues in the US, Europe, and Asia, he helped organize the International Aerosol Research Assembly (IARA) and hosted the First International Aerosol Conference in Minneapolis in 1984. In other professional activities, Liu served as a member of the Science Advisory Board and Clean Air Science Advisory Committee of the U.S. Environmental Protection Agency (1992-95), and a member of the Board of Scientific Counselors of the National Institute of Occupational Safety and Health (1991-98). For his exceptional contributions to the teaching, research and service missions of the University of Minnesota, the Board of Regents conferred on him a Regents Professorship in 1993, the highest honor that the University can bestow upon a faculty member. He was inducted into the National Academy of Engineering in 1987 for his contribution to solar energy research and aerosol instrumentation and was also inducted in the Minnesota Science and Technology Hall of Fame in 2011. For his outstanding achievement in aerosol research, the International Aerosol Research Assembly awarded him the Fuchs Memorial Award, the most prestigious award in the aerosol field, given out only once every four years. Liu received numerous other university, national, and international awards, including the R.C. Jordon professorship in the Mechanical Engineering Department at the University of Minnesota (1989), an Honorary Doctorate at the University of Kupio in Finland (1991), a Senior U.S. Scientist Award by the Alexander von Humboldt Foundation in Germany (1982), the distinguished engineer award from the Minnesota Society of Professional Engineers and Minnesota Federation of Engineering Societies, and the lifetime achievement award of American filtration and separation society. Professor Othmar Preining, former chair of the Clean Air Commission, Austrian Academy of Sciences, called Dr. Liu, "The Pioneer of Aerosols and Global Climate Change".

Professor Chris Hogan, Head of the Mechanical Engineering Department at the University, commented on Professor Liu's accomplishments in the ME department. "Professor Ben Liu was a founding father and intellectual giant in fields of aerosol science, air pollution control, and particle technology. To this day the methods we use to make aerosol and particle measurements stem from his laboratory. His pioneering research and vision for not only how to measure and quantify airborne particles but also how to filter and control them in our environment made the University of Minnesota the premiere institution for aerosol research."

After he retired from the University, Liu continued to explore new frontiers. In 1987 he founded the MSP Corporation with his colleague, the late Professor Virgil Marple, and served as the Board Chair and President. The company designed, developed, and manufactured advanced technology products for the semiconductor, pharmaceutical, and air pollution control industries for sales and distribution world-wide. The company received the Deloitte & Touche Minnesota Fast 50 award for rapid revenue growth in its first four years of operation, the Tibbetts Award, and the IR-100 Award for innovative new product development. Over a period of 20+ years, the company grew to 55 employees, including a wholly owned subsidiary in South Korea. Liu designed and invented new products, working with younger engineers, teaching, and learning from them, and creating a vibrant organization that provided professional opportunities for all.

Former MSP Senior Manager, Dr. Francisco Romay wrote about Liu's achievements at MSP Corporation. "During the 19 years I had the honor to work with Dr. Liu at MSP, I was always amazed by his great intellect and fearless commitment to help solve industry problems by developing aerosol instrumentation and clever devices for semiconductor manufacturing tools with MSP's engineering team. In addition to that, he always made an effort to personally know his employees and families during the yearly Christmas celebrations held at the company." The MSP Corporation was acquired by TSI Incorporated in 2016. Ben and Helen then retired fully at the age of 83 in 2017. TSI honored Liu by sponsoring the Benjamin Y.H. Liu/TSI Applied Technology Chair Professor at the Mechanical Engineering Department at the University of Minnesota.

Ever humble and generous with his talent and time, he was an exceptional mentor for his students and friends. Ben has never talked about his accomplishments. He and his wife, Helen (deceased), were a model couple for a truly caring and loving relationship. If you ask him the greatest accomplishment of his life he will mention he was the ping pong champion at the University of Nebraska and the husband to Helen. When Ben and Helen moved from their Ralph Rapson home in North Oaks, all he brought over was a plaque of his ping pong award! In between his academic demands, he always found time for Helen, to travel and play tennis. They were inseparable. He would also say "Helen was the brains of the relationship, she was so smart and remembered every detail of everything, she was the backbone of the relationship." Ben and Helen were very active in the Chinese community in Minnesota. Belonging the Chinese Heritage Foundation. Liu was the recipient of the distinguished Chinese alumni award. They were generous donors to the academic and arts causes, have established over ten scholarship funds, and would donate their legacy to charity. They also produced multiple productions at the Guthrie theatre and were vital to bringing Chinese Opera to the United States. Left to manage their philanthropic goals and the Liu Family Foundation is their granddaughter, Amanda. She estimates that they have donated over $5 million dollars in charitable giving thus far, primarily to the Guthrie Theatre and the University of Minnesota. Helen had a love for the arts and Ben had a love for education.

Preceded in death by wife, Helen, beloved son, Larry, survived by granddaughter, Amanda Liu Olson, and grandson-in-law, Cory Olson, great-granddaughter, Elysia Liu Olson, and great-grandson, Cameron Thomas.

A celebration of life will be held at the North Oaks Golf Club on July 13th from 3-6 pm. The public is welcome to attend and enjoy complimentary food and beverages.

A Memorial to celebrate Benjamin Liu's lifetime achievements will be held at the University of Minnesota, on August 21, 2025. Immediately after the MN Aerosol Measurement Short course, when several of his former students from around the world will come to teach the Short Course. Please check for details in ME News in early August at https://cse.umn.edu/me/news.

The burial will be in Kona, Hawaii on January 28th 2026 with his immediate family in attendance. His ashes will be scattered in the Kona Bay at the exact location his wife and son were laid to rest in 2020.

In lieu of gifts/flowers please make a donation to the Liu Family Foundation with the Minneapolis Foundation.