ADVERTISEMENT

Self-powered Paper-based Diagnostics At The Point Of Care Testing

Providing high-quality medical diagnostics in low-resource settings, such as forward-deployed military units, rural areas in Africa, or in the middle of natural disaster scenarios, requires portable laboratories that should be affordable, easy to transport, easy to use (even by minimally trained users), and independent of infrastructure.

While a variety of portable solutions have been proposed to diagnose some of these health problems and infectious diseases, their dependence on cumbersome/expensive equipment, refrigeration conditions, and skilled personnel prevents their adoption by first responders and healthcare personnel who require accurate and quantitative results in resource-limited settings. Without a rapid, deployable, and field-sustainable diagnostic tool, healthcare workers in low-resource areas and natural disaster sites are forced to make their decisions based on observed symptoms, which, usually begin 4-6 days after infection and are often mild and can be easily mistaken for those of flu or other viral infections.

ADVERTISEMENT

The FlexiLab, research group lead by Prof. Ramses Martinez at Purdue University, used cellulose paper, rendered superhydrophobic using spray coating, to fabricate self-powered, paper-based, electrochemical devices (SPEDs) capable of performing accurate medical tests at the point of care. SPEDs have two functional layers: A top layer containing self-pipetting microfluidic channels distribute urine or blood samples over the electrochemical and colorimetric test zones (see Figure 1).

Figure 1: Electrochemical and colorimetric tests. Credit: Ramses V. Martinez

The bottom layer of the SPEDs is a paper-based triboelectric generator capable to harvest electric energy from the charges at the fingertips of the user. To perform an electrochemical test using SPEDs, the user needs to connect them to an inexpensive small portable circuit called “potentiostat” (see Figure 2), tap the back of the SPED for about 3 minutes so the triboelectric generator can charge the rechargeable battery of the potentiostat, and apply a fingerprint of blood on the top layer of the SPED that will serve as a sample for the medical diagnostic test.

Figure 2: Potentiostat. Credit: Ramses V. Martinez

The paper-based tribogenerators integrated into SPEDs were able to not only provide enough energy to run electrochemical tests but also re-charge small batteries, which could be used in parallel to recharge a cellphone. This provided the first example of how self-powered, paper-based electrochemical devices could be used to facilitate telemedicine applications, using a machine-vision algorithm capable to identify the shape and orientation of colorimetric tests in a digital image, to apply an adaptive color image filter to minimize color artifacts from illumination conditions and to interpret the results of the tests (see Figure 3). After the SPEDs are used to perform up to 4 electrochemical tests and 10 colorimetric assays, they can be easily disposed of by burning (see Figure 4).

Figure 3: Colorimetric test results. Credit: Ramses V. Martinez

SPEDs proved to be capable of detecting and measuring different analytes such as glucose, uric acid and L-lactate in blood; pH, ketone, hemoglobin, white blood cells, etc. in urine. These biomarkers correspond to the detection and monitoring of diseases related to liver and kidney function, malnutrition and anemia. Future work envisages the detection and monitoring of biomarkers for infectious diseases in remote areas such as HIV, dengue fever, yellow fever, malaria, and hepatitis.

ADVERTISEMENT

This study, Self-Powered, Paper-Based Electrochemical Devices for Sensitive Point-of-Care Testing was recently published in the journal Advanced Materials Technologies.

Comments

READ THIS NEXT

What Is Pi (Definitely Not Pie)?

If you remember anything from high school math, odds are you remember pi (and no, we don’t mean the delicious […]

What Are Expressed Powers: Definition And Examples

With respect to the United States legal and political system, the expressed powers (also called enumerated powers or delegated powers) are those powers […]

How To Find Horizontal Asymptotes

A horizontal asymptote is a horizontal line on a graph that the output of a function gets ever closer to, […]

Colors Of The Rainbow In Order

The colors of the rainbow in order are red, orange, yellow, green, blue, indigo, violet. You can remember them with […]

Being Good At Multiplayer Video Games Linked To Higher Intelligence, Study Finds

A recent study has found a link between playing certain video games and increases in certain types of intelligence. It […]

Evaluating Rodent Aerobics For Preclinical Ischemic Stroke Intervention Assessments

One might probably associate rodents, particularly mice and rats, with sewers, cargoes, ships, or perhaps with an exceptional “French chef” […]

A Bacterial Cell Imaging Method Using CRISPR And Microfluidics

With the rise in bacterial strains that are resistant to available antibiotics, there is a growing need to better understand […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?