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The V-Chip provides instant, quantitative diagnostic results in the form of a bar graph.  Each line of the graph corresponds to a different test. The V-Chip provides instant, quantitative diagnostic results in the form of a bar graph. Each line of the graph corresponds to a different test. Lidong Qin and Yujun Song

New Medical Diagnostics Chip Charts Advance in Rural Health 

Diagnosing diseases or conditions, such as HIV or diabetes, often involves a great deal of specialized laboratory work utilizing costly equipment.  These tests are typically done using the ELISA (Enyzme-linked immunosorbent assay) method, which measures changes in the color of a patient sample when mixed with specific enzymes.  

Such tests are limited in their availability and usefulness for remote or resource-limited communities due to time and cost constraints; but a new class of low-cost, easy-to-use devices, known as microfluidics chips, has sought to change that.

The latest in this line of development is the V-chip, created at The Methodist Hospital Research Institute and MD Anderson Cancer Center in Houston, TX.  Microfluidics chips, like the V-chip, are credit card sized devices made of plastic, paper, or in this case, glass, that perform all of the diagnostics of an ELISA test (at a reasonable level of certainty) with little expertise or additional equipment.

In a microfluidics device, micro-scale channels, etched into the base material, allow for a small quantity of sample fluid, such as blood, to mix with various enzymes.  These enzymes react with particular protein markers in the sample that indicate disease or other medical conditions.

V-Chips advance this technology further by providing instant, quantifiable results.  While many microfluidics devices to date still require some form of optical analysis (using a spectrometer or microscope), the V-chip generates a bar-chart based on the amount of a particular protein marker in the sample (for example, insulin when testing for diabetes).  Furthermore, the V-chip can perform up to 50 different tests at once.

This is possible because unlike an ELISA test, the V-chip does not rely on color change to identify protein markers.  Rather, oxygen is generated in the enzyme reaction; this pressurizes the micro-channels and pushes a red dye into parallel vertical lines, forming a bar chart.  The length of each bar on the chart corresponds to the amount of oxygen created in that channel and thus the amount of each protein marker present in the sample.

The upshot of this technology (and microfluidics in general) is that advanced, low-cost diagnostics tests can be carried out with minimal training and little energy consumption at the patient’s point-of-care.  This increases the capabilities of remote or resource-limited health facilities that would otherwise need to send samples to a national reference laboratory, which could take days or weeks to return results.

Even in hospitals with easy access to ELISA laboratory equipment and trained technicians, the benefits are stark.  Lab equipment needed to conduct HIV tests using ELISA can cost anywhere from $7,000 to $25,000, and may include computers, an incubator, a refrigerator/freezer, a centrifuge and a spectrophotometer.  Each test may cost from $10 - $90 and could take up to 24 hours to process.

Power load requirements for these various equipment run upwards of 1,000 W, and UPS systems are generally required, adding to the expense and maintenance associated with ELISA testing.  

The technical and logistical capabilities needed to support such testing are also considerable.  Laboratory technicians must receive specific training and national health systems must be able to track and document the movement of patient samples and results along their network of health labs.

While microfluidics devices like the V-Chip have only seen some trial applications in developing countries so far, the underlying benefits of the technology - easy, versatile and low-cost lab diagnostics - are impossible to ignore.  Combining these tests with other advancements in rural medicine, such as mHealth and telemedicine – sending smartphone images of test results to be analyzed – may finally give remote and underserved populations access to a degree of affordable, high-quality healthcare.

In Guyana, UDAID’s Improving Health Facility Infrastructure Project (IHFI) is confronting a number of challenges to providing healthcare in remote settings through adequate power supply and cold chain capacity. Guyana’s rural health facilities often serve those populations most vulnerable to illnesses like HIV, which require laboratory expertise and cold chain-dependent supplies to diagnose and treat. The benefits of medical advances like the V-Chip are compounded by the difficultly of coordinating and sustaining healthcare networks over long distances and difficult terrain.

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