As cardiovascular diseases (CVDs) are the leading cause of death worldwide, it is of great importance to realize a rapid and sensitive diagnosis. Multiple CVD biomarker detection, which holds higher accuracy and speed of early CVD diagnosis, is becoming a promising alternative to single biomarker analysis. Cardiac troponin I (cTnI), C-reactive protein (CRP), brain-type natriuretic peptide (BNP), and heart fatty acid binding protein (H-FABP) are four significant diagnostic biomarkers for CVDs. Among the several methods for biomarker detection, such as optical, magnetic, mechanical, and electrical methods, the magnetic method stands out because of its stability, low toxicity, noninvasive detection, facile manipulation with an external magnetic field, and immunity to the interference of background light. At present, the lack of multiplexing capability, the imprecision of magnetic signal localization, and the agglomeration and non-specific adsorption of magnetic nanoparticles all limit the clinical application of magnetic detection. This paper presented a novel method for multiple CVD biomarker detection using a spin exchange relaxation-free (SERF)-based microfluidic platform. One or more SERF atomic magnetometers were used to scan the remanent field of magnetic labels to detect four CVD biomarkers in 70 min, with a detection limit of 1.88 pg/mL (cTnI), 1.58 pg/mL (CRP), 1.45 pg/mL (BNP), and 1.71 pg/mL (H-FABP). The results showed two-dimensional magnetic fields with a resolution of submillimeter level and a sensitivity of pT level. The measurement technique provides a new magnetic methodology for applications in clinical diagnosis.
Alkali metal vapor cells are fundamental components in quantum sensors, and their relaxation characteristics critically influence both sensitivity and system stability. In Spin-Exchange Relaxation-Free (SERF) atomic magnetometers, although spin-exchange collisions are effectively suppressed, wall-collision-induced relaxation remains the primary limiting factor. A coating-enabled buffer-gas-free vapor cell (CBF-VC) is proposed as a novel sensor unit, realized through multilayer octadecyltrichlorosilane (OTS) selfassembled molecular coatings. The CBF-VC is integrated into a single-beam SERF atomic magnetometer, and experimental validation is conducted. The results indicate a significant extension of the wall collision relaxation time from 40.19 ms. This extended relaxation time directly enhances the magnetometer sensitivity by 48%, confirming the feasibility of CBF-VCs as a measurement-oriented vapor cell architecture. The findings demonstrate not only the effectiveness of anti-relaxation coatings, but also a new instrumentation pathway for advancing next-generation quantum sensing.
HAOTIAN CHI,JUNYING ZHANG,HENG YUAN,ZHONGYU CAI,SHENG ZOU,WEI QUAN
The most sensitive spin-exchange relaxation-free (SERF) magnetometer generally requires a working temperature greater than 100 ∘ C. To date, octadecyltrichlorosilane (OTS) coating is one of the best candidates for this temperature range. However, the performance and consistency of the OTS coatings within the alkali-metal vapor cells are still poor. In this paper, the formation of OTS coatings on borosilicate glass (BG) substrates was investigated. The effects of ambient relative humidity (RH) on the formation of OTS coatings were examined by atomic force microscopy (AFM) and contact angle measurement. The results showed that 75 % RH can improve the order of the OTS coatings and reduce the root mean square (RMS) roughness of the OTS coatings. Under three different ambient RHs, the soaking time of OTS molecules should be greater than 60 min to form complete OTS coating.
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