Microfluidics integration of acoustic biosensors is an actively developing field. Despite significant progress in "passive" microfluidic technology, integration with microacoustic devices is still in its research state. The major challenge is bonding polymers with monocrystalline piezoelectrics to seal microfluidic biosensors. In this contribution, we specifically address the challenge of microfluidics integration on gallium arsenide (GaAs) acoustic biosensors. We have developed a robust plasma-assisted bonding technology, allowing strong connections between PDMS microfluidic chip and GaAs/SiO at low temperatures (70 °C). Mechanical and fluidic performances of fabricated device were studied. The bonding surfaces were characterized by water contact angle measurement and ATR-FTIR, AFM, and SEM analysis. The bonding strength was characterized using a tensile machine and pressure/leakage tests. The study showed that the sealed chips were able to achieve a limit of high bonding strength of 2.01 MPa. The adhesion of PDMS to GaAs was significantly improved by use of SiO intermediate layer, permitting the bonded chip to withstand at least 8.5 bar of burst pressure. The developed bonding approach can be a valuable solution for microfluidics integration in several types of MEMS devices.
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http://dx.doi.org/10.3390/mi13050755 | DOI Listing |
Sensitive detection of incident acoustic waves over a broad frequency band offers a faithful representation of photoacoustic pressure transients of biological microstructures. Here, we propose a plasmon waveguide resonance sensor for responding to the photoacoustic impulses. By sequentially depositing Au, MgF, and SiO films on a coverslip, a composite waveguide layer produces a tightly confined optical evanescent field at the SiO-water interface with extremely strong electric field intensity, enabling the retrieval of photoacoustic signals with an estimated noise-equivalent-pressure (NEP) sensitivity of ∼92 Pa and a -6-dB bandwidth of ∼208 MHz.
View Article and Find Full Text PDFSensors (Basel)
November 2024
Shenzhen Key Laboratory of Advanced Thin Films and Applications, GuangDong Engineering Technology Research Centre of Breath Test, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Prostate-specific antigen (PSA) is a well-established tumour marker for prostatic carcinoma. In this study, we present a novel, real-time, and ultrasensitive Love-mode surface acoustic wave (L-SAW) immunosensor for PSA detection enhanced by MoS@CuO-Au nanocomposite conjugation. The MoS@CuO-Au nanocomposites were analyzed by SEM, XRD, and EDS.
View Article and Find Full Text PDFFood Res Int
December 2024
School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China. Electronic address:
Aflatoxin B (AFB) is a highly toxic substance found in food, necessitating rapid and sensitive detection methods. Combining interfacial capacitive sensing with AC electrothermal (ACET) enrichment, an aptasensor based on a PCB electrode array is developed for real-time detection of trace AFB. Owing to the sensitive solid-liquid capacitance with a pF-level resolution, AFB detection at sub-femtomolar level is achieved.
View Article and Find Full Text PDFThis paper summarizes several attractive surface acoustic wave (SAW) biosensors, including Love-wave sensors, dual-channel SAW sensors, langasite SAW sensors, and SAW syringe filters. SAW sensors with different piezoelectric materials and high-frequency SAW sensors used for identifying the food pathogenic bacteria () are discussed together with the examples of methods based on such sensing technology that have been effectively utilized in diagnostics and epidemiological research. This review also emphasizes some of the limitations of using these biosensors, which have prompted the increased need for more rapid, sensitive, selective, portable, power-efficient, and low-cost methods for detecting these pathogens.
View Article and Find Full Text PDFBiosens Bioelectron
January 2025
State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, 300072, China. Electronic address:
Microfluidic-based nucleic acid testing (NAT) has been proven as an alternative approach for in-situ and rapid NA detection. However, these on-chip methods still require complex peripherals, which contradict the purpose of point-of-care (POC) applications. One of the major challenges is the integration of NA purification and amplification in a miniaturized setup with high mass and heat transfer efficiency.
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