(Source: Juan Gaertner)
Twin-tailed version is eight times as fast

If it looks like a sperm and swims like a sperm, it must be a .... cyborg?
I. Part Man, Part Machine, Pure Spermlike Terror
That's true, if you're talking about the "tiny swimming bio-bots" designed by the lab of University of Illinois mechanical science and engineering Professor Taher Saif.  Professor Saif and his student research team took a thin filament of polydimethylsiloxane (PDMS) -- a silicone plastic commonly used in The Wendy's Comp. (WEN) fries and McDonald's Corp. (MCD) nuggets and fries -- and mounted cultured human heart cells (cardiomyocytes) to it.
They hail their "spermbot" "the first synthetic structures that can traverse the viscous fluids of biological environments on their own."

Professor Saif brags:

Micro-organisms have a whole world that we only glimpse through the microscope.  This is the first time that an engineered system has reached this underworld.  It's the minimal amount of engineering -- just a head and a wire.  Then the cells come in, interact with the structure, and make it functional.

The swimmer doesn't find it hard at all to thrust its way into foreign environments, plunging through the dark, wet depths of its test environments.

spermbot wide
The spermbot's design mirrors the real thing. [Image Source: Nature Communications]

Flagella (pl., singular: flagellum), of course are not solely found in the sperm of higher eukaryotes.  They are also commonly found as feelers in single-celled eukaryotes such as protists and plants, plus prokaryotes such as bacteria, archaebacteria.  The cultured heart cells intrinsically self-assemble and learn to throb rhythmically to propel the tiny cyborg (robot+living organism).

Spermbot Micrograph

The little squirt can swim at a frisky pace of 5 to 10 μm per second.  Researchers found that they could improve on nature's design, though, if they equipped the cyborg with twin tails. 

Spermbot speed
The spermbot is a spirited swimmer. [Image Source: Nature Communications]

The twin-tailed variant motored along at a randy rate of 81 μm per second, over eight times as fast as the garden-variety build.
II. Next Up: Spermbot Sensors
The work is funded by U.S. National Science Foundation (NSF) grants and is one of the research programs at the school's NSF-supported Beckmann Advanced Science and Technology Center.  Center director Roger Kamm enthuses:

The most intriguing aspect of this work is that it demonstrates the capability to use computational modeling in conjunction with biological design to optimize performance, or design entirely different types of swimming bio-bots.  This opens the field up to a tremendous diversity of possibilities. Truly an exciting advance.

The current research was published in the prestigious peer-reviewed journal Nature Communications.

Professor Taher Saif
Professor Taher Saif. [Image Source: Univ. of Illinois]

The team next plans to penetrate new applications with multi-tailed variants of the swimmer, which will allow for even greater speeds and mobility, plus affix biosensors and local control molecules to put the tiny swimmer to good use.

Professor Saif remarks:

The long-term vision is simple. Could we make elementary structures and seed them with stem cells that would differentiate into smart structures to deliver drugs, perform minimally invasive surgery or target cancer?
A rendering of a human sperm [Image Source: Juan Gaertner/Shutterstock]

The spermbot joins the ranks of past robots such as the "cicada" drone and rumored "dragonfly" drone, which were inspired by nature.  But its cyborg structure is a new and unique twist on this familiar theme.  Let's hope it's on our side.

Sources: Nature Communications, University of Illinois

"And boy have we patented it!" -- Steve Jobs, Macworld 2007

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