Smartphone microscope creates interactive tool for microbiology

A new 3-D printed, easily assembled smartphone microscope developed at Stanford University turns microbiology into game time. The device allows kids to play games or make more serious observations with miniature light-seeking microbes called Euglena.

“Many subject areas like engineering or programming have neat toys that get kids into it, but microbiology does not have that to the same degree,” said Ingmar Riedel-Kruse, an assistant professor of bioengineering. “The initial idea for this project was to play games with living cells on your phone. And then it developed much beyond that to enable self-driven inquiry, measurement and building your own instrument.”

Riedel-Kruse named his device the LudusScope after the Latin word “Ludus,” which means “play,” “game” or “elementary school.” He and first author Honesty Kim, a graduate student in Riedel-Kruse’s lab, are set to publish details of the LudusScope in PLOS ONE on Oct. 5.

Playing with cells

The LudusScope consists of a platform for the microscope slide where the Euglena swim freely, surrounded by four LEDs. Kids can influence the swimming direction of these light-responsive microbes with a joystick that activates the LEDs.

Above the platform, a smartphone holder positions the phone’s camera over a microscope eyepiece, providing a view of the cells below.

On the phone, children can run a variety of software that overlay on top of the image of the cells. One looks like the 1980s video game Pac-Man, with a maze containing small white dots. Kids can select one cell to track, then use the LED lights to control which direction the cell swims in an attempt to guide it around the maze and collect the dots. Another game looks like a soccer stadium. Kids earn points by guiding the Euglena through the goal posts.

Other non-game applications provide microscope scale-bars, real-time displays of swimming speed or zoomed-in views of individual cells. These let kids collect data on Euglena behavior, swimming speed and natural biological variability. Riedel-Kruse encourages teachers to have students model the behaviors they see using a simple programming application called Scratch, which many kids already learn in school.

Each of the elements, from the plastic microscope to the chamber that holds the Euglena, is something youngsters can build themselves from simple, easily available parts.

Complex beginnings

The project began as part of a Stanford bioengineering class Riedel-Kruse taught, with much more complex parts. But he wondered if the elements could be simplified for younger learners.

“We wondered if we could make it so easy to replicate that even middle-schoolers could build it,” he said.

In its current iteration, a teacher who wanted to use the device in class could start with the open-source 3D printing patterns and software included as part of the paper. An increasing number of schools have 3D printers, but those that don’t can send the plans to a professional printer. That produces pieces to construct the stage that holds a microscopic slide and a holder for the microscope eyepiece and smartphone.

For the joystick controller, students would need to wire a small circuit out of common electronics parts to receive signals from the joystick and transmit them to the LEDs.

Euglena are already commonly used in classrooms and they can be purchased through biological supply companies. For the game, Euglena swim within a chamber made by adhering strips of double-sided tape to the slide and to the cover slip.

The act of building, observing, interacting and modeling the cells fits easily within the new science learning guidelines emphasized by the Next Generation Science Standards being adopted by many schools, Riedel-Kruse said.