David L. Shenkenberg, email@example.com
LOS ANGELES – Some biological events happen so quickly that ordinary cameras simply miss those crucial shots – of neurons firing, proteins moving and lasers performing surgery, just to name a few.
Shimadzu Corp.’s HPV-1 is perhaps the fastest commercially available CCD camera in the world, capturing images at a rate of 1 million frames per second. However, it relies on high-power illumination to achieve reasonable sensitivity at those speeds, and high-power illumination can damage biological samples.
The Fesca-200 streak camera from Hamamatsu is very fast but can take pictures only of recurring events. Likewise, the pump-probe method favored by most biologists works only with repetitive events. To capture extremely rare ones, an entirely new camera is needed.
Grad student Kevin Tsia, professor Bahram Jalali and postdoctoral researcher Keisuke Goda pose beside their STEAM camera.
UCLA engineers led by professor Bahram Jalali believe that they have developed the fastest camera in the world. Their STEAM camera runs at 6.1 million fps, with a shutter speed of 440 ps. STEAM is an acronym for serial time-encoded amplified microscopy.
The STEAM camera doesn’t use ordinary CCD or CMOS sensors. Instead, it uses ultrashort laser pulses that are converted into a serial data stream not unlike a fiber optic network. The laser pulses are simultaneously amplified and stretched in time to the point that they are slow enough to be captured with an electronic digitizer.
“The setup on the left is part of the next-generation STEAM camera. The STEAM camera described in the Nature paper has been partly dismantled and [is] being transformed into this new STEAM camera,” said Keisuke Goda of UCLA, the postdoctoral researcher who did most of the work on the project.
As detailed in the April 30 issue of Nature, the researchers used the technique to capture images of 10- to 30-µm-diameter metal balls moving through microfluidic channels at a flow rate of approximately 2.4 meters per second. The imaging method also magnified the balls 316 times.
In the future, the researchers will use tumor cells instead of metal balls because the most immediate and important application of the camera that Jalali foresees is detecting rare circulating tumor cells in the bloodstream – a condition that can lead to the spread of cancer beyond the original site.
Currently, the most common way of detecting individual cancer cells is to take a blood sample and run it through a machine called a flow cytometer. This small blood sample is a mere fraction of all the blood in a patient’s body. Ideally, the entire bloodstream of a patient could be monitored so that even a single tumor cell could be caught. The STEAM camera just might be able to do this.
“We are currently developing the next-generation STEAM camera to take high-resolution images of cancer cells at tens of million frames per second,” said Keisuke Goda, the postdoctoral researcher who developed the STEAM camera along with Jalali and grad student Kevin K. Tsia.