Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

and bathroom, constantly monitoring our health and detecting diseases like cancer years before they become a danger. The key to this is the DNA chip, which promises a “laboratory on a chip.” Like the tri-corder of
Star Trek,
these tiny sensors will give us a medical analysis within minutes.
    Today, screening for cancer is a long, costly, and laborious process, often taking weeks. This severely limits the number of cancer analyses that can be performed. However, computer technology is changing all this. Already, scientists are creating devices that can rapidly and cheaply detect cancer, by looking for certain biomarkers produced by cancer cells.
    Using the very same etching technology used in computer chips, it is possible to etch a chip on which there are microscopic sites that can detect specific DNA sequences or cancer cells.
    Using transistor etching technology, DNA fragments are embedded into the chip. When fluids are passed over the chip, these DNA fragments can bind to specific gene sequences. Then, using a laser beam, one can rapidly scan the entire site and identify the genes. In this way, genes do not have to be read one by one as before, but can be scanned by the thousands all at once.
    In 1997, the Affymetrix company released the first commercial DNA chip that could rapidly analyze 50,000 DNA sequences. By 2000, 400,000 DNA probes were available for a few thousand dollars. By 2002, prices had dropped to $200 for even more powerful chips. Prices continue to plunge due to Moore’s law, down to a few dollars.
    Shana Kelley, a professor at the University of Toronto’s medical school, said, “ Today, it takes a room filled with computers to evaluate a clinically relevant sample of cancer biomarkers and the results aren’t quickly available. Our team was able to measure biomolecules on an electronic chip the size of your fingertip.” She also envisions the day when all the equipment to analyze this chip will be shrunk to the size of a cell phone. Thislab on a chip will mean that we can shrink a chemical laboratory found in a hospital or university down to a single chip that we can use in our own bathrooms.
    Doctors at Massachusetts General Hospital have created their own custom-made biochip that is 100 times more powerful than anything on the market today. Normally, circulating tumor cells (CTCs) make up fewer than one in a million cells in our blood, but these CTCs eventually kill us if they proliferate. The new biochip is sensitive enough to find one in a billion CTCs circulating in our blood. As a result, this chip has been proven to detect lung, prostate, pancreatic, breast, and colorectal cancer cells by analyzing as little as a teaspoon of blood.
    Standard etching technology carves out chips containing 78,000 microscopic pegs (each 100 microns tall). Under an electron microscope, they resemble a forest of round pegs. Each peg is coated with an antibody for the epithelial cell adhesion molecule (EpCAM), which is found in many types of cancer cells but is absent in ordinary cells. EpCAM is vital for cancer cells to communicate with one another as they form a tumor. If blood is passed through the chip, the CTC cells stick to the round pegs. In clinical trials, the chip successfully detected cancers in 115 out of 116 patients.
    The proliferation of these labs on a chip will also radically affect the cost of diagnosing disease. At present, it may cost several hundred dollars to have a biopsy or chemical analysis, which might take a few weeks. In the future, it may cost a few pennies and take a few minutes. This could revolutionize the speed and accessibility of cancer diagnoses. Every time we brush our teeth, we will have a thorough checkup for a variety of diseases, including cancer.
    Leroy Hood and his colleagues at the University of Washington created a chip, about 4 centimeters wide, that can test for specific proteins from a single drop of blood. Proteins are the building blocks of life. Our muscles, skin, hair, hormones, and enzymes are all made of proteins. Detecting proteins from diseases like cancer could lead to an early warning system for the body. At present, the chip costs only ten cents and can identify a specific protein within ten minutes, so it is several million times more efficient than the previous system. Hood envisions a day when a chip will be able to rapidly analyze hundreds of thousands of proteins, alerting us to a wide variety of diseases years before they become