Computers that cost tens of millions of dollars in the 1970s were much slower that computers of today that cost a few hundred dollars in hand-held personal digital assistants (PDAs). That pattern is going to repeat over the next two decades with biotechnology as cheap mass-manufactured microfluidic "labs on a chip" and nanoparticles replace big expensive medical testing equipment and make medical testing doable by anyone. Picture a cheap device that can test for millions of different biomolecules in a single sample of tissue or blood.

CAMBRIDGE, Mass.--MIT researchers have created an inexpensive method to screen for millions of different biomolecules (DNA, proteins, etc.) in a single sample-a technology that could make possible the development of low-cost clinical bedside diagnostics.

The work, based on tiny customizable particles, could also be used for disease monitoring, drug discovery or genetic profiling. Even though the particles are thinner than the width of a human hair, each is equipped with a barcoded ID and one or more probe regions that turn fluorescent when they detect specific targets in a test sample.

Using a new, extremely versatile technique, the researchers can produce a "virtually unlimited" array of particles to test for DNA, RNA, proteins and other biomolecules, said Daniel Pregibon, a graduate student in chemical engineering at MIT.

Pregibon is the lead author of a paper on the work that will appear in the March 9 issue of Science.

He and co-author Patrick Doyle, the Doherty Associate Professor of Chemical Engineering, believe their particles could become an effective and inexpensive way to perform medical diagnostic tests at a patient's bedside.

Current testing methods are cost-prohibitive for bedside use, Pregibon said. The MIT particles are inexpensive to manufacture, and their results are as accurate, if not more so, than the results from more expensive systems, he said.

Cheap biomedical testing equipment won't just get used at bedsides in hospitals. The far bigger use of cheap, small, and highly automated test equipment will be in homes. Bedstands will have sensors that check for signs of disease in exhaled breath. Sensors in sinks will check spit. Toilets will contain sensors that analyze urine and feces. Bathroom mirrors will contain safe low power lasers that'll briefly scan your mouth and eyeballs and skin for signs of diseases.

Just living in a house will put you in an effortless but very detailed and constant medical testing regimen. There'll be no need for a Star Trek medical tricorder because the scanning equipment will be built into houses and cars and even watches and jewelry. Medical testing won't require a trip to a doctor. Testing and even most diagnosis will happen in home computers running medical expert systems.

But back to this latest step toward cheap and ubiquitous medical testing technology: When a particle binds to a target molecule that activates flourescent barcode pattern.

One end of each particle is a fluorescent "dot-pattern" barcode that reveals what the target molecule of the particle is, and the other end is loaded with a probe and only turns fluorescent if the target molecule is present. The particles can also be designed to each test for multiple targets, by adding several unique regions.

"We can make the particles, encode them and add functionality all in a single step," said Pregibon.

Small stuff can get made cheaply. This is small stuff. Some day it'll be dirt cheap.

After exposure to a sample (e.g. some blood serum) the particles flow through a microfluidic device and read to see if they bound to anything in he sample.

To rapidly "read" the particles, the researchers designed a custom "flow cytometer" using a microfluidic device and standard microscope. In this flow-through system, the oblong, disk-like shape of the particles ensures that they are precisely aligned for accurate scanning. Each time a particle flows past a detector, its barcode is read and the corresponding target is quantified.

The microparticles are inexpensive because they can be produced efficiently in a single step. The design of the particles also makes the scanning devices cheaper. With multiple distinct regions, the barcode can be read and the target quantified using a single fluorescent color, which greatly simplifies detection.

Again, biotechnology is going the way of computer technology. Biotechnology manufacturing will use much of the same materials, equipment, and processes used to make semiconductor computer chips. Microfluidic devices for biomedical testing will be mass produced for cheap mass market personal medical test equipment. Most medical testing will not get done in hospitals and doctor's offices. Most diagnosis will get done by expert systems before you ever step foot in a doctor's office.

Then will come the nanobots that'll do repairs.