What do bubbles, cells, and dancers have in common?

With an empty stage as her backdrop, one dancer pulses out into the light, her long hair swishing against her back in time with the music as she dips and weaves to an up-tempo beat.

She’s soon joined by another dancer, then another, and they keep coming in a steady, rhythmic stream. One group begins to bunch and break away, clustering around the leader as they move together across the stage, while a second group converges and bobs fluidly in a different direction.

This is not your average dance troupe, and the dance they’re performing is not your average production.

The result of a Virginia Tech collaboration between Shima Shahab, an assistant professor in the Department of Biomedical Engineering and Mechanics, and Billie Lepczyk, a professor of dance in the School of Performing Arts, this dance has been designed according to one simple – if unique – guiding principle. The movement of dancers on stage is meant specifically to mimic the “dancing” movement of tiny gas bubbles that have been stimulated by acoustic waves within a microfluidic channel.

This choreographed motion not only helps engineers better visualize and analyze the microscopic bubbles’ dancing phenomena, but it could also inform advancements in acoustic cell sorting, a field that has shown promise in developing non-invasive treatments for diseases like cancer.  

For the skeptics out there who think biomedical engineering and dance may be an unlikely pairing, Shahab said it’s all about changing your perspective.  

“Engineers can learn a lot from dance,” said Shahab. “There are many similarities between our research and this choreography. For example, they both develop through practice, are experimental, and focus on producing desired outcomes within physical constraints.”

Shahab also explained that choreography and a design-based approach to engineering are both creative processes that rely heavily on innovative approaches.

“These are concepts that can connect engineers as well as artists,” she said.

Dancers Under the Microscope

It was that sense of connection that first led Shahab to reach out to Lepczyk last year. Shahab, along with her research team, had been experimenting with using ultrasound waves to manipulate materials within microfluidic channels.

In the lab, Marjan Bakhtiari-Nejad, an engineering mechanics doctoral student, and Ahmed Elnahhas, a then-undergraduate in the mechanical engineering program, had been designing and testing these microfluidic channels, which are tiny chip-like structures that can be used to control liquids and other substances on a sub-millimeter scale.

When the researchers streamed acoustic waves across fluid in the channel, they discovered that the behavior of bubbles – which had been introduced into the channel at regular intervals – suddenly changed. The bubbles clustered together in interesting patterns, bobbed around one another, and moved in tandem.

“It looked like they were dancing,” said Shahab. Together the team began to analyze the acoustic waves and their effects on the bubbles’ movement.

Shahab wondered what that dancing motion would look like on a larger scale, or even on a stage.

How would an actual dancer interpret these movements? From a dancer’s perspective, did an analytical explanation for the bubbles’ motion exist? And how might biomedical engineers apply that information to their research?

Shahab wanted to find out.

“I contacted Billie and after an initial brainstorming session, we decided to choreograph a dance based on these bubbles,” said Shahab. “Yes, it’s a biomedical concept, but it’s also art. We thought, ‘Let’s put them together.’”

Using Sound to Sort Cells

Meanwhile, Shahab had been discussing the implications of acoustic sorting and manipulation with colleague Rafael Davalos, the L. Preston Wade Professor in the Department of Biomedical Engineering in Mechanics.

“I found her research fascinating,” said Davalos, who has a background in using microfluidic devices to isolate rare cell populations, particularly in brain cancer. Together with Shahab, he began thinking about using acoustic sorting in his work with cells, an area of research first pioneered at the Massachusetts Institute of Technology in 2016.

“This method could be a very elegant, passive way to pull out certain cell types of interest from a larger population,” he said. “Immediately we started thinking this could be used for biomedical applications – either in conjunction with or as an alternative to other techniques.”

Because cells possess different physiological properties – in their structural makeup, for example – they respond differently to varying frequencies of sound. The hope is that researchers will be able to separate specific cell types, like cancerous or diseased cells, from healthy cells based on how they respond to ultrasound waves – just like the dancing bubbles Shahab first saw under her microscope.

Those isolated cells could then be targeted for non-invasive drug delivery or other types of treatment, while healthy cells remain unharmed.  

“Most of the techniques I’ve been using in my research are more electrical-based,” said Davalos.  “So when I saw what she could do with sound, and how controllably she could manipulate those bubbles, the wheels started turning.”

Finding Synchrony

In spring 2018, Lepczyk circulated an advertisement calling for dancers on campus to participate in a transdisciplinary project. The only requirements? An interest in applying engineering concepts to dance, and an ability to attend the scheduled rehearsals and performance.

The resulting dance troupe consisted of 19 undergraduate students with 16 different majors from five different colleges at Virginia Tech.

“The students also had a wide range of dancing abilities, from beginner to advanced,” said Lepczyk. “This was new territory for a lot of them.”

After watching videos of Shahab’s dancing bubbles in the microfluidic channel, Lepczyk had choreographed a production that prioritized movement influenced by sound, one in which the dancers’ interactions would be constrained to a small stage.

“I chose a piece of music that had an even beat but no melody,” said Lepczyk. “The students had no musical cues, so they had to sense each other’s movements in synchrony, like a oneness. They had to pick up on that and work together. Even the experienced dancers in the group had never done that before – they had to find this synchrony alongside the inexperienced dancers. And I think as the choreographer, I connected with that element as well.”

After several rehearsals, the final production – a sequence of three separate dances – was filmed from a variety of angles in the Cube at Virginia Tech’s Moss Arts Center. Shahab, Davalos, and their respective research teams have already begun watching and analyzing the video footage for insights they can bring back to the lab.

Sound far-fetched?

That’s the point, said Shahab and Davalos. For engineers who work on incredibly complex problems and systems, often under a microscope, radical approaches that challenge assumptions can often lead to the next breakthrough.

“Usually when you come up with a solution, you’re rarely working on the actual problem,” said Davalos. “You just need to take a step back and think about it from a different angle.”

Davalos added that seeing the recorded dance has already led him to explore several new applications for the research. “That bird’s-eye view, that change in perspective, can really help you come up with those bigger ideas,” he said. 

Toward a Common Goal

Although the first dance has come to a close, Shahab and Lepczyk will continue their collaboration into subsequent phases of the project. And as Shahab’s research progresses, so will iterations of Lepczyk’s choreography.

Shahab will next introduce beads into the microfluidic channel to see how they respond to the acoustic waves, then eventually cells. She will continue to consult with Davalos on potential applications for acoustic cell sorting throughout these next phases.

While the implications for biomedical engineering continue to be an important motivator of the project, both Shahab and Lepczyk said one of the most exciting results so far has come from the involvement of the student dancers.  

“We had a group of students coming from different backgrounds, different majors, and different levels of experience, then we put them in this confined space and gave them a task,” said Shahab. “And they enjoyed it.”  

Lepczyk was also impressed by the students’ cooperation and teamwork, as well as their willingness to connect with each other while working towards a common goal. “They got to know people they wouldn’t have met otherwise,” she said. “When you move and dance together, you begin to understand each other better. I’ve seen that with dance. There’s a communal feeling of humanity. You’re together, and you’re working together.”

This project was funded in part by the Virginia Tech Institute for Critical Technology and Applied Science, the Virginia Tech Institute for Creativity, Arts, and Technology, and the Virginia Tech Fralin Life Science Institute.