A device that detects biomarkers and identifies diseases by performing electrochemical analyses and reads out the colour- coded test results has been developed by researchers at the Purdue University.
The new medical-diagnostic device is made of paper, and is powered by the user’s touch. The device self-powered, paper-based electrochemical devices or SPEDs, aims to provide sensitive diagnostics to patients in regions that have limited access to resources or medical equipments.
The test is initiated by placing a pinprick of blood in a circular feature on the device, which is less than two-inches square. SPEDs also contain “self-pipetting test zones” that can be dipped into a sample instead of using a finger-prick test.
“You could consider this a portable laboratory that is just completely made out of paper, is inexpensive and can be disposed of through incineration,” said Ramses V. Martinez, an assistant professor of industrial and biomedical engineering at Purdue University. “We hope these devices will serve untrained people located in remote villages or military bases to test for a variety of diseases without requiring any source of electricity, clean water, or additional equipment.”
The device runs on microfluidic channels in which electrochemically detected colorimetric assays are carried out. SPEDs have
a structure comprising of two layers.The top layer is fabricated using untreated cellulose paper with patterned hydrophobic “domains” that define channels that wick up blood samples for testing. These “microfluidic channels” allow for accurate assays that change color to indicate specific testing results.
The bottom layer is a “triboelectric generator,” or TEG, which generates the electric current necessary to run the diagnostic test simply by rubbing or pressing it.
Additionally, a machine-vision diagnostic application also was created to automatically identify and quantify each of the “colorimetric” tests from a digital image of the SPED, perhaps taken with a cellphone, to provide fast diagnostic results to the user and to facilitate remote-expert consultation. The researchers also designed an inexpensive handheld device called a potentiostat, which is easily plugged into the SPED to automate the diagnostic tests so that they can be performed by untrained users. The battery powering the potentiostat can be recharged using the TEG built into the SPEDs.
“To our knowledge, this work reports the first self-powered, paper-based devices capable of performing rapid, accurate, and sensitive electrochemical assays in combination with a low-cost, portable potentiostat that can be recharged using a paper-based TEG,” Martinez said.
The team further is trying to build the devise with additional layers so as to promote more complex assays capable of diagnosing a range of infectious diseases including dengue fever, yellow fever, malaria, HIV, and hepatitis.
