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When the feature size of integrated circuits (ICs) reaches nanometer, nano contaminant particles (CPs) on the surface of semi-finished devices during processing may cause serious device defects, while effective real-time CP detection techniques are still unavailable, especially when the CPs are of low concentration. Using a gold interdigitated electrode fabricated on a ceramics substrate, a sensitive sensor for ultra-trace nano CP detection in cleaning fluids is developed, which employs an optimized detection signal integrating the nanofluidic enrichment of nanoparticles (NPs) into interfacial capacitance measurement. The detection can achieve a limit of detection of 102 particles/mL with a response time of 30 s. The logarithmic linear range of this sensor reaches (102 - 107) particles/mL for CPs of 10 nm in grain diameter, which can meet the test demand of practical concentration. This sensor has capability to detect CPs of different material and size, and the operation is real-time and nondestructive. In addition, it is demonstrated to work reliably in solutions with different conductivity. The detection protocol is simple, and the sensor as well as the impedance analyzer for test also has advantages in portability and cost efficiency for industrial-scale on line application. This work provides a feasible and promising approach for IC fabrication’s quality evaluation through ultra-trace nano CP detection in used cleaning liquid samples.

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.