A diagnostic device made out of paper detects biomarkers and identifies diseases by performing electrochemical analyses — powered only by the user’s touch — and reads out the color-coded test results, making it easy for non-experts to understand.

Paper-based diagnostic detects biomarkers and identifies diseases.
(Credit: Purdue University/Aniket Pal)

The self-powered, paper-based electrochemical devices, or SPEDs, are designed for sensitive diagnostics at the point-of-care, or when care is delivered to patients, in regions where the public has limited access to resources or sophisticated medical equipment.

The test is initiated by placing a pinprick of blood in a circular feature on the device, which is less than 2 in. square. SPEDs also contain self-pipetting test zones that can be dipped into a sample instead of using a finger-prick test.

The top layer of the SPED 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. A machine-vision diagnostic application also was created to automatically identify and quantify each of these colorimetric tests from a digital image of the SPED to provide fast diagnostic results facilitate remote consultation.