Low-Cost and Desktop-Fabricated Biosensor for Rapid and Sensitive Detection of Circulating D-Dimer Biomarker

Disposable point-of-care biomedical applications demand low-cost biosensing systems that can provide rapid detection with accessible fabrication requirements and user-friendly operation. Here, we present an easy-to-operate and cleanroom-free desktop-fabricated biosensor that is capable of reliable detection for human D-dimer biomarkers on-site. Interdigitated electrodes are used as the biosensor, and they are fabricated using commercial compact discs and home-made gadgets. The compact disc-based electrode arrays are patterned by wet-etching and followed by electroplating of polypyrrole (PPy). The nano-porous structures of PPy enhance the immobilization of protein probe on the electrode surface. The sensor performance is further enhanced by the ac electrokinetics (ACEK) capacitive sensing method. ACEK capacitive sensing induces ACEK effects that direct analytes toward the electrode surfaces, significantly promoting probe-target binding. Our sensor can quantitatively detect D-dimer biomarkers in 1 min with a limit of detection of 1 pg/mL. In contrast, Nyquist or Bode plots can only qualitatively distinguish positive and negative samples. Furthermore, the total cost of each test, together with the lithography material and compact disk, is only around U.S. $1, and it is acceptable to be disposable. The sensitive device yields wide-ranging and significant advantages for biomedical and lab-on-a-chip applications for undeveloped areas.