As devices for disease detection and diagnosis become more advanced, they also are becoming smaller. Next-generation technologies for faster detection of diseases such as cardiovascular disease, melanoma, and breast cancer are handheld devices that are easy to use, portable, and more accurate than many of the currently available diagnostic tools. As the following examples illustrate, immediate diagnosis and detection of life-threatening diseases may soon be held in the palm of your hand.
Microfluidic Test Chip
IBM scientists have created a one-step, point-of-care-diagnostic test, based on a silicon chip, that requires less sample volume, is significantly faster, portable, easy to use, and can test for many diseases, including one of the world’s leading causes of death, cardiovascular disease. A patient’s serum or blood sample could be tested immediately following a myocardial infarction, commonly known as a heart attack, to enable the doctor to quickly take a course of action to help the patient survive.
IBM Research-Zurich scientists Luc Gervais and Emmanuel Delamarche, in collaboration with the University Hospital of Basel in Switzerland, have developed a new diagnostic test that uses capillary forces to analyze tiny samples of serum, or blood, for the presence of disease markers, which are typically proteins that can be detected in people’s blood for diagnostic purposes. Capillary action force is the tendency of a liquid to rise in narrow tubes or to be drawn into small openings. An everyday example of a capillary action force can be viewed by dipping a paper towel in a cup of water — the microstructures in the paper fiber enable the towel to absorb the water.
IBM scientists have encoded the forces of capillary action on a microfluidic chip made of a silicon compound, similar to those used in computer chips. The chip, which measures 1 × 5 centimeters, contains sets of micrometer-wide channels where the test sample flows through in approximately 15 seconds, several times faster than traditional tests. The filling speed can be adjusted to several minutes when the chip requires additional time to read a more complex disease marker.
The microfluidic chip consists of a microscopic path for liquids with five stages:
- Stage 1: A one-microliter sample, 50 times smaller than a teardrop, is pipetted onto the chip, where the capillary forces begin to take effect.
- Stage 2: These forces push the sample through an intricate series of mesh structures, which prevent clogging and air bubbles from forming.
- Stage 3: The sample then passes in a region where microscopically small amounts of the detection antibody have been deposited. These antibodies have a fluorescent tag and similar to the antibodies within our body, they recognize the disease marker and attach to it within the sample. Only 70 picoliters (a volume one million times smaller than a tear) of these antibodies are used, making their dissolution in the passing sample extremely fast and efficient.
- Stage 4: The most critical stage is called the “reaction chamber,” and it measures 30 micrometers in width and 20 micrometers in depth, roughly the diameter of a strand of human hair. Similar to a common pregnancy test, in this stage the disease marker that was previously tagged is captured on the surface of the chamber. By shining a focused beam of red light, the tagged disease markers can be viewed using a portable sensor device that contains a chip similar to those used by digital cameras, although this one is much more sensitive. Based on the amount of light detected, medical professionals can visually confirm the strength of the disease marker in the sample to determine the next course of treatment.
- Stage 5: Less a stage and more a part of the entire process is the capillary pump. The capillary pump, which has a depth of 180 micrometers, contains an intricate set of microstructures, the job of which is to pump the sample through the device for as long as needed and at a regular flow rate, just like the human heart. This pump makes the test accurate, portable, and simple to use. IBM scientists have developed a library of capillary pumps so that tests needing a variety of sample volumes or test times can still be done without having to re-engineer the entire chip.
IBM scientists designed the chip with flexibility in mind in both its form and uses. Due to its small size, the chip can be embedded in several types of form factors, depending on the application, including a credit card, a pen, or something similar to a pregnancy test. Besides diagnosing diseases, the test is also flexible enough to test for chemical and biohazards.
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Handheld Melanoma Detector
Electro-Optical Sciences (EOS) of Irvington, NY, has created MelaFind®, a computerized handheld diagnostic device for non-invasive early detection of malignant melanoma, which could be used by a doctor or nurse while a patient is still in the office. The EOS technology has been applied to the detection of early melanoma, the early detection of tooth decay, for chronic wound management, and it has potential applications for the early detection of other cancers.
EOS designed MelaFind to assist in the evaluation of pigmented skin lesions, including atypical moles, which have one or more characteristics of melanoma, before a decision to biopsy has been made. MelaFind acquires and displays multispectral (from blue to near-infrared) digital images of pigmented skin lesions and uses automatic image analysis and statistical pattern recognition to help identify lesions to be considered for biopsy to rule out melanoma, the deadliest form of skin cancer.
The MelaFind system consists of a handheld imaging device comprised of several components:
- an illuminator that shines light of 10 different specific wavelengths, including near infrared bands;
- a lens system composed of nine elements that creates images of the light reflected from the lesions;
- a photon (light) sensor; and
- an image processor employing proprietary algorithms to extract many discrete characteristics or features from the images.
The “brains” of the MelaFind system are mathematical algorithms that distinguish melanoma from non-melanoma by comparing the lesions’ features with the characteristics of the benign and malignant lesions stored in a proprietary MelaFind database.
EOS submitted a Premarket Approval (PMA) application for MelaFind to the U.S. Food and Drug Administration (FDA) in June 2009. The company has conducted a prospective clinical study, and according to EOS, for all subgroups analyzed, the sensitivity of MelaFind was greater than 95%, and MelaFind specificity was statistically significantly higher than that of study clinicians.
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Breath Test for Detecting Breast Cancer
Early breast cancer detection can significantly improve survival rates. However, current diagnostic tests expose women to the potentially harmful effects of radiation, and often fail to detect cancer in the earliest stages.
A team of researchers from Georgia Tech, Emory University, and the University of Ulm in Germany are using a portable, non-invasive device to determine which biomarker gases exhaled in a person’s breath indicate the presence of breast cancer.
“Scientists know that it’s possible to detect different chemical compounds from a person’s breath and relate them to illness,” said Charlene Bayer, principal research scientist at the Georgia Tech Research Institute (GTRI). “Yet, they haven’t been able to quantify results such as determining a patient has a tumor because he or she has X amount of Y compounds in his or her breath.”
Breath biomarkers are volatile organic compounds originating in the lower lungs. Certain compounds are related to oxidative stress, the body’s response to inflammation, and are often an indication of disease.
As a patient breathes into the device, these compounds are trapped and examined by a sensor. The researchers’ sensing methodology combines gas chromatography — a technique for separating complex compounds — with mass spectrometry, which identifies the chemical makeup of a substance. Specific patterns in the compounds are then found and used to confirm the presence or absence of the disease.
The team recently conducted a clinical study analyzing more than 300 volatile organic compounds in breath samples of 20 healthy women over the age of 40, and 20 women recently diagnosed with stage II-IV breast cancer who had not received treatment. The results showed that the breath analysis was able to determine whether the sample came from a cancer patient or healthy subject 78% of the time.
The researchers are currently adding to their clinical database of breath data and trying to determine which compounds are most important for detecting breast cancer. That could help reduce the number of compounds tested.
Because it can offer immediate results in a physician’s office, the device could help increase early detection among those who do not have the resources for a mammogram, more easily conduct interval testing for those with a genetically high risk for breast cancer, and facilitate recurrence testing after breast cancer treatment.
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