One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20ms, indicating a very high efficiency of pulse driving.
A method to fabricate suspended silicon nanowires that are applicable to electronic and electromechanical nanowire devices is reported. The method allows for the wafer-level production of suspended silicon nanowires using anisotropic etching and thermal oxidation of single-crystal silicon. The deviation in width of the silicon nanowire bridges produced using the proposed method is evaluated. The NW field-effect transistor (FET) properties of the device obtained by transferring suspended nanowires are shown to be practical for useful functions.
OBJECTIVE: The purpose of the present study was to determine the prognostic significance of the neutrophil-lymphocyte ratio (NLR) in recurrence of cervical intraepithelial neoplasia (CIN).METHODS: We evaluated the NLR as a prognostic marker in the entire cohort of 230 patients who had undergone surgical resection and were diagnosed with CIN. Subjects were categorized into two different groups based on the NLR (NLR-high and NLR-low) using cutoff values determined by receiver operating characteristic (ROC) analysis. The primary research objective for this study was to validate the impact of the NLR on recurrence-free survival (RFS) in patients with CIN. The secondary objective was to evaluate the impact of other hematologic parameters on RFS in CIN patients.RESULTS: Using the entire cohort, the most appropriate NLR cut-off value for CIN recurrence selected on the ROC curve was 2.1. The NLR-low and NLR-high groups included 167 (72.6%) and 63 patients (27.4%), respectively. According to Kaplan-Meier analysis, RFS rates during the entire follow-up period were considerably lower in the NLR-high group than in the NLR-low group (P = 0.0125). In multivariate survival analysis using Cox proportional hazard model, we identified the NLR, absolute eosinophil count (AEC), hemoglobin concentration, and mean corpuscular volume (MCV) as valuable prognostic factors that impact RFS.CONCLUSIONS: The NLR is an independent prognosticator for RFS following surgical resection in CIN patients. We also found that the AEC, hemoglobin level, and MCV were strongly associated with RFS, as determined by multivariate analysis using a Cox model. These hematological parameters might provide additional prognostic value beyond that offered by standard clinicopathologic parameters.
Efforts to date in silicon nanowire research have primarily focused on the nanowire synthesis and the demonstration of individual nanowire-based devices exhibiting interdisciplinary potential spanned from electrical (Duan et al 2003 Nature 425 274–8; Cui and Lieber 2001 Science 291 851–3; Morales and Lieber 1998 Science 279 208–11) through biomedical applications (Cui et al 2003 Science 293 1289–92; Zheng et al 2005 Nature Biotechnol. 23 1294–301). However, the realization of integrated nanowire devices requires well ordered assembly of a silicon nanowire (Huang et al 2001 Science 291 630–3; Whang et al 2003 Nano Lett. 3 1255–9) as well as simple and cost effective fabrication. Here we describe a simple fabrication scheme and a large-scale assembly of silicon nanowires by combining top-down fabrication with nanowire transfer onto another insulator substrate for device manufacture. Our innovative fabrication method enables us to obtain well defined silicon nanowires as a freestanding bridge structure with a diameter of 20–200 nm and a length varying from 5 to 100 µm using micro-machining processes. Direct transfer of the freestanding nanowires simply provides large-scale assembly of silicon nanowire on various substrates for highly integrated devices such as high-performance thin-film transistors (TFTs) (Duan et al 2003 Nature 425 274–8; Ishihara et al 2003 Thin Solid Films 427 77–85) and nanowire-based electronics (Cui and Lieber 2001 Science 291 851–3). Electrical transport properties of the transferred silicon nanowire were also investigated.
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