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Microfluidics: Miniature Chemistry Labs

Posted by michael on from the make-jello-using-one-third-vodka dept.

enkidu writes: "The NYTimes has a story (free reg, yaba yaba) about the rapidly emerging field of microfluidics and describes some of the methods used in making micro-valves, pumps and other components. In the future, you won't need to send your blood/urine sample to a lab, your doctor will put in his "lab-in-a-box" and hand you a printout before your leave."

3 of 57 comments (clear)

  1. But the insurance companies won't allow it... by printman · · Score: 5, Insightful

    A lot of doctors ran out an bought their own mini-lab test equipment when it first came out. Not only did it cost them less than sending it out to be processed, but they got results faster.

    *However*, the insurance companies have put a stop to that. My doctor has to send out my bloodwork and wait almost a week to check my cholesterol, instead of using his own equipment and getting me an answer within an hour or so... In the process, I end up paying *more* to my insurance company and they get to negotiate mass-quantity lab work with the lowest bidder.

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    I print, therefore I am.
    1. Re:But the insurance companies won't allow it... by cplmd · · Score: 5, Insightful

      As a physician, it's not just the insurance companies to blame - if fact not them at all. It's how our wonderful federal government responds to a few of my unscrupulous colleagues.
      Specifically, Rep. Pete Stark in his three versions of Stark Acts have reduced how much a physician can do for you. Pharmacies, labs and x-ray cannot be owned or used by the doctor if he does have an interest in the facility. I don't have a problem with that given the kickbacks a few doctors got in the past.
      However, as always with federal regulation of individual/local problems, it has extended into areas that no longer make sense and actually make it worse for you as a patient. This office-lab in a box being a case in point.
      While on my soap box, it would be nice if the federal government limited and regulated the legal, esp. civil court system as much as the medical one. Given spiraling malpractice insurance costs and the actual closure of some rural hospitals due to legal liability and insurance costs, maybe as the federal government did with medicare/medicad in setting limits on what reimbursement would be to doctors and hospitals for a given disease, lawyers in this country should be limited in what they are paid for say a divorce, murder defense or malpractice / workman's comp. case.

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      just leave me alone and i'll leave you alone - there - isn't that easier and better?
  2. Re:Won't this hurt accuracy? by baz00f · · Score: 5, Informative

    Speaking as a pedigreed biochemist, you are correct in the extreme of vanishingly small samples. But these devices are still working with enough volume such that an analyte of interest at a substantial concentration (glucose, cholesterol, etc.) is effectively present at the same concentration at nearly all sample volumes.

    Things DO fall apart (as you intuit) when the concentration of the analyte gets vanishingly small. We see this routinely when we try to quanitate DNA using PCR (Polymerase Chain Reaction) methods. PCR is sensitive enough that we can detect ONE copy of a DNA molecule in a volume of sample. So if you have say, one copy in 1ml of volume, and you sample .1 ml and do your PCR, your test would come up negative upon repeats (on average) 9 out of 10 times. With small numbers of copies you can use Poisson statistics to calculate your hit rate. With higher concentrations your Poisson distribution collapses to a gaussian that gets narrower and narrower, which is the regime that most normal wet analytical techniques work. For example, fasting blood glucose is about 100 mg/dl, which is about 5 mM. Assuming your device can work with 1 nanoliter sample size (this is about 100x smaller than a volume about the size of the proverbial period at the end of a sentence) you would have 3x10^12 molecules of glucose in it. Assuming your technique is sensitive enough to register the presence of this "small" number of molecules, you are still far away from seeing sampling errors on repeats of the same sample due to random fluctuations of the number of molecules (the "concentration") in any given sample.

    Paul Yager at U. Washington (Seattle) has a good introduction to microfluidics:

    Microfluidics Tutorial and Prognostication