Versatile low‐cost digital lock‐in amplifier suitable for multichannel phase‐sensitive detection

1989 ◽  
Vol 60 (7) ◽  
pp. 2257-2259 ◽  
Author(s):  
S. Carrato ◽  
G. Paolucci ◽  
R. Tommasini ◽  
R. Rosei
Keyword(s):  
Low Cost ◽  
Sensitive Detection ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Lock In

Development of an Impedance Meter Based on a Digital Lock-In Amplifier with 4-Kelvin-Probe Electrodes

2021 ◽  
Vol 18 (4) ◽  
pp. 1171-1176
Author(s):  
Rafael da Silva Ferraz ◽  
Raiff Sales da Fonseca ◽  
Cláudio Bastos da Silva ◽  
Horácio Tertuliano Santos Filho
Keyword(s):  
Embedded System ◽  
Experimental Tests ◽  
Sensitive Detection ◽  
Signal Acquisition ◽  
Kelvin Probe ◽  
C Language ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Lock In ◽  
Mathematical Operations

In this paper, it is described a new design of a digital Lock-In amplifier applied to 4-Kelvin- probe electrodes for the measurement of complex electrical variables. The proposed design is based on the operation of a Phase Sensitive Detection (PSD) circuit and on signal acquisition by the Nyquist principle. The hardware basically consists of a programmable embedded system and an analog interfacing circuit. The microcontroller within the circuit was programmed using standard C language for portability and performs the acquisition of the resulting signal along with mathematical operations. Experimental tests on the prototype have shown that it performs as theoretically predicted.

scholarly journals CO2 Methanation over Rh/CeO2 Studied with Infrared Modulation Excitation Spectroscopy and Phase Sensitive Detection

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 601
Author(s):  
Felix Hemmingsson ◽  
Andreas Schaefer ◽  
Magnus Skoglundh ◽  
Per-Anders Carlsson
Keyword(s):  
Reaction Pathway ◽  
Sensitive Detection ◽  
Side Reactions ◽  
Co2 Methanation ◽  
Individual Contributions ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Modulation Excitation Spectroscopy ◽  
Modulation Excitation

Methane is a well-established fuel molecule whose production from CO 2 through methanation garners increasing interest as an energy storage solution. While often produced with Ni based catalysts, other metals are of interest thanks to higher robustness and activity-selectivity numbers. The Rh/CeO 2 catalyst has shown appreciable properties for CO 2 methanation and its structural dynamics has been studied in situ. However, the reaction pathway is unknown. Here, we present infrared modulation excitation spectroscopy measurements with phase sensitive detection of a Rh/CeO 2 catalyst adsorbate composition during H 2 pulsing (0–2 vol.%) to a constant CO 2 (0.5 vol.%) feed. Various carbonyl (CO) and carbonate (b-CO 3 /p-CO 3 ) ad-species clearly respond to the hydrogen stimulus, making them potential reaction intermediates. The different CO ad-species are likely intermediates for product CO and CH 4 but their individual contributions to the respective formations are not unambiguously ascertained. As for the carbonate dynamics, it might be linked to the reduction/oxidation of the CeO 2 surface upon H 2 pulsing. Formate (HCOO) ad-species are clearly visible but appear to be, if not spectators, linked to slow side reactions possibly also affected by CeO 2 redox processes.

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