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Slicing cells and time

Engineers at The University of Texas at Austin have created surgical lasers so accurate that they can destroy single cells leaving their neighbors unaffected.

Mechanical engineering Assistant Professor Adela Ben-Yakar says that with the system they developed:

“You can remove a cell with high precision in 3-D without damaging the cells above and below it…And you can see, with the same precision, what you are doing to guide your microsurgery.”

This is all accomplished with a femtosecond laser and a powerful type of 3 dimensional microscopy.

A femtosecond laser is a special laser that can shoot pulses of light lasting 50 to many hundreds of femtoseconds. A femtosecond is really tiny unit of time. Take a billionth of a second……now divide that into a million pieces. That’s a  quadrillionth of a second.  In a little more than one second, light can get to the moon; in 50 femtoseconds it can’t even travel the width of a human hair.

Pulses of laser light that short are too brief to transfer heat to the material its cutting. Material is heated so quickly past the boiling point that it’s turned into an ionized plasma that quickly dissipates.

The other and equally important side of this surgical coin is the 3D imaging required to make sure you’re aiming at a sick cell and not a healthy one. This is accomplished by two-photon fluorescence microscopy. Basically, nearby cells are caused to fluoresce by the molecular absorption and release of pairs of photons. Cells farther away do not glow so they cannot confuse the targeting mechanism.

These two technologies have never been brought together before into one device. In fact, the device is so small that within a few years it may be ready to be used in endoscopic surgery. If you’ve have any experience with this surgery you know how amazing it is. Instead of one long nasty surgical incision; several small incisions are made. Using very compact surgical tools and cameras, complicated surgeries can be performed. The benefit is how non-invasive endoscopic surgery is. Recovery time is a fraction what it used to be, not to mention the tiny scars. My father had part of his kidney removed recently using this technique. All he has is 3 little scars and his recovery was much faster than it would have been.

As fast as recovery can be with normal endoscopic surgery, it will be even faster with this new technology since tissue removal is so precise. I know what you’re thinking. How long will it take when you’re zapping once cell at a time? Imaging software will allow surgeons to target one cell at a time or use algorithms to detect diseased cells and destroy them automatically. Ok now…stop thinking about those cosmetic lasers that run amuck in Logan’s Run. That was just a movie.

As you may have suspected, femtosecond lasers have applications far beyond just obliterating cells. Obviously their precision is ideal for many non-biological cutting and machining applications but beyond that they’re invaluable for making movies. A laser making movies? Yup. Lasers can be used as the world’s fastest still camera. Put a lot of stills together and you have a movie. The first laser pulse starts a chemical reaction; the second pulse bounces off the reacting molecule which then becomes the first snapshot. Subsequent pulses take more snapshots each separated by mere femtoseconds of time. This is the temporal resolution we need to see things like a molecule falling apart as it undergoes a chemical reaction. I’ve even seen this being referred to as femto-chemistry. The fundamental knowledge we gain about this realm could lead to tremendous advances in industrial processes, drug development, who knows what else.

Femtosecond lasers are cool and all but can we do even better?
Actually, femtosecond lasers aren’t even cutting edge anymore (so to speak). The next milestone which we’ve already reached is the…….attosecond laser. An attosecond is 10 to the -18th(10^-18) of a second or one quintillionth of a second. This is the time it takes light to traverse 3 hydrogen atoms. To really put this tiny whiff of time into perspective (which isn’t even really possible) consider that one attosecond compared to a second is like one second compared to the age of the universe.

The briefest of laser pulses ever created are in the attosecond range, specifically 80 attoseconds.

At this timescale we could elucidate more fully the behavior of electrons since they orbit hydrogen atoms in about 150 attoseconds. This could lead to a much deeper understanding of mind-benders like superconductivity and giant magnetoresistance used to store data in hard drives.

You know I have to keep going right? I can’t help myself. So what’s next? Next is the Marx Brother interval called a zeptosecond. This is 10^-21 of a second or one sextillionth of a second. Alas, no lasers yet exist that probe events separated by zeptoseconds.

This will no longer be the case though if a lasetron is ever created. Calculations show that powerful lasers may be able to accelerate electrons in such a way that they emit zeptosecond bursts of radiation. This could freeze frame the fleeting events that take place in the nucleus of atoms like protons and neutrons coming together or coming apart during nuclear fission.

At 10^-24 of a second we have a trillionth of a trillionth of a second or a yoctosecond. During this uber brief septillionth of a second the activities of quarks within protons and neutrons take place. I don’t think anyone’s even thinking about how a laser could squeeze between these tiny intervals of time.

After the yoctosecond we have a wide interval of almost 20 orders of magnitude where most science-related websites don’t even list any prefixes to put in front of the word “second”.

In the basement though we find one final time slice. The so called Planck Time. This is named after physicist Max Planck considered to be the father (or maybe grandfather) of quantum theory.  At about 10^-43 seconds, It doesn’t get smaller than this folks. This unit of time is the smallest possible interval that has any meaning given our understanding of space-time. It is truly a quantum of time. Therefore, if we look at the moment of the big bang being time Zero; the next possible moment of time where anything could happen was 10^-43 seconds later. Anything before that has no meaning.

Kind of like what a wife think about her husband’s life before they met.

5 comments to Slicing cells and time

  • MindBlown

    Hi Rogues, I’m new to the forum and looking forward to participating. Fascinating story on the laser. As someone who knows a young girl with a particularly difficult brain tumor, I couldn’t help but wonder how feasible this technology could be for attacking brain tumors, where such precision could be invaluable for preserving life with all the brain’s functionality intact. I suppose if there were a way to stain or otherwise identify the cancerous cells, view them in this 3D microscope and pick them off one by one with the laser, a doctor could emerge from the surgery much more confident that she or he had gotten ALL of the tumor, and perhaps resulting in less reliance on the problematic use of chemotherapy and/or radiation that is often used instead of or in addition to surgerical removal of a tumor. I hope for those now or soon to be afflicted with the disease, that day could come very very soon.

  • Traveler

    I’ve always wondered how they measure these pulses. Sure your laser is fast, but how do you go about finding out that it’s N attoseconds?

  • Jim Shaver

    That’s way cool, Bob. It’s hard enough to envision a machine that can create a coherent pulse of light that is just over a hundredth of a millimeter long (50 femtoseconds). But then, the 80-attosecond laser pulse you mentioned would be only 24 nanometers long! That’s smaller than the shortest wavelength of visible light, which makes me wonder, can these pulses of light be shorter than one wavelength? If not, the 80-attosecond laser would have to be at least ultraviolet. Then again, a single photon is smaller than one wavelength at any frequency, and we know single-photon “light beams” exist.

    Sorry, it’s just hard to wrap my brain around these things. Hold on, let me think about it for a few more yoctoseconds, then I’ll get back to you.

  • petrucio

    Cool stuff.

    “The benefit is how non-invasive this.”

    Sorry, but this sentence made absolutely no sense.

  • Sorry, the word gremlins must have deleted the “is” at the end of that sentence.

    “The benefit is how non-invasive this is.”

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