Ultra-low noise front-end design for smart optical sensors with high sensitivity and wide dynamic range.

Ultra-low noise is a critical component in the design of high-precision sensor front-ends. We introduced differential phase-sensitive detection (d-PSD) to mitigate both multiplicative and additive noise in optical sensors, aiming for an enhanced performance and cost-effectiveness. The d-PSD combines a capacitive transimpedance amplifier (C-TIA), a delta-sigma analog-to-digital converter (ΔΣ-ADC), and a software-based lock-in amplifier (s-LIA). The first two components utilize the DDC112 (a dual current input 20-bit ADC) for a minimal analog channel length, thus reducing noise efficiently, while the latter employs a cost-effective 32-bit microcontroller unit (MCU), the HC32F460. This approach was successfully implemented as the front-end for a smart optical sensor. Testing indicated that the sensor achieved an equivalent current noise level of 0.6 nA/√Hz, primarily attributed to the light source driver rather than the sensor's front-end circuit. The sensor exhibited an exceptional performance, with a 3σ measurement precision of 5.4 × 10-4 over a 1-second integration time and a dynamic range of 100 dB, leveraging the proposed method and design. Furthermore, the front-end of the sensor boasts a compact size, low power consumption, and affordability, making it an ideal, versatile solution for ultra-high precision, smart optical sensors.

Effects of arc types on the laser-arc synergic effects of hybrid welding.

A dimensionless parameter of melting energy increment (ψ) was employed to quantify the synergic effect in laser-arc hybrid welding. The greater of the ψ, the stronger of the synergic effect. The ψ at different welding parameters of laser-tungsten inert gas and laser-metal inert gas hybrid welding was calculated and compared. The former had a stronger synergic effect than the latter because the change range of ψ was far wider than that of the latter, which was -59.3-83.6% and 1-23%, respectively. The differences were discussed according to the electrode mode and the migration behavior of charged particles in the plasmas.

[Study on Monosaccharide Compositions of Polysaccharide in Dendrobium Stems of Different Resources by PMP-HPCE].

OBJECTIVE: To establish a PMP-HPCE method for comparing the monosaccharides of polysaccharide in tissue-cultured and wild Dedrobium huoshanese and Dedrobium moniliforme as well as wild Dedrobium henanese, in order to investigate the similarities of their bioactive components. METHODS: The PMP-monosaccharides of polysaccharide from the five investigated Dedrobium samples were separated by HPCE on a fused silica capillary column(100 cm x 50 µm) at 25 °C with 350 mmol/L BAS (adjusted to pH 10 with 1.0 mol/L NaOH) as running buffer for 34 min. The applied voltage was 20 kV and the detection wavelength was set at 250 nm. RESULTS: Total six monosaccharides including xylose, glucose, mannose, galactose, galacturonic acid and ribose were detected in the five Dendrobiurms samples and the similarity coefficients between the ten batches of the same Dendrobium species were all above 0. 98,while remarkable dissimilarity were exhibited among species and different resources. CONCLUSION: PMP-HPCE technique combined with chemometrics is simple, convenient, precise, reproducible and proved to be an effective strategy for identifying the species and origins, especially in the quality assessment of Dendrobium stems.