Detection Limit Of Sensor Research Articles

Prospects for Developing Low-Cost Optical Fiber Sensors for Liquid-Liquid Interface Detection

This work examines the prospects of a low-cost retroreflection optical sensor system for detection of the interface between two immiscible liquids, for applications in oil separation tanks. The sensor in its simplest configuration comprises a bare fiber optic tip, cleaved at an angle of 90º relative to the longitudinal fiber axis. The device tested experimentally is based on a 2x2 bidirectional coupler, which connects the sensor tip to a laser and two photodetectors, one used to measure the signal and the other as a reference. From experiments conducted in a laboratory wateroil system, the measured retro-reflected signal was very small, and of the same order as the differential signal due to low optical contrast liquids. To overcome this difficulty, the detection system was designed with an amplification stage, followed by filtering of the digitally converted signal. With this strategy, an accuracy of 99.7% was reached. On the light of the performance measured by the bare fiber tip configuration, an analysis on the potential improvement in performance obtained, by applying a thin layer of gold to the tip of the sensor, was made. Simulated results indicated that, for an optimized gold film, 13 nm thick, a 13fold improvement in the sensor detection limit is obtained.

Preparation of a pH-responsive controlled-release electrochemical immunosensor based on polydopamine encapsulation for ultrasensitive detection of alpha-fetoprotein.

To accomplish ultra-sensitive detection of alpha-fetoprotein(AFP), a novel electrochemical immunosensor using polydopamine-coated Fe3O4 nanoparticles (PDA@Fe3O4 NPs) as a smart label and polyaniline (PANI) and Au NPs as substrate materials has been created. The sensor has the following advantages over typical immunoassay technology: (1) The pH reaction causes PDA@Fe3O4 NPs to release Prussian blue (PB) prosoma while also destroying the secondary antibody label and immunological platform and lowering electrode impedance; (2) PB has a highly efficient catalytic effect on H2O2, allowing for the obvious amplification of electrical impulses; (3) PANI was electrodeposited on the electrode surface to avoid PB loss and signal leakage, which effectively absorbed and fixed PB while considerably increasing electron transmission efficiency. The sensor's detection limit was 0.254pg·mL-1 (S/N = 3), with a detection range of 1pg·mL-1 to 100ng·mL-1. The sensor has a high level of selectivity, repeatability, and stability, and it is predicted to be utilized to detect AFP in real-world samples.

Sulfur-Doped Graphene-Based Electrochemical Sensors for Fast and Sensitive Determination of (R)-(+)-Limonene from Beverages.

Two sensors based on sulfur-doped graphene, a gold nanoparticle paste modified with 5,10,15,20-tetraphenyl-21H,23H-porphine and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin, were proposed for the determination of R-limonene in beverages (triple sec liqueur and limoncello). Differential pulse voltammetry was the method used to characterize and validate the proposed sensors. The response characteristics showed that the detection limits for both sensors were 3 × 10−6 mol L−1, while the quantification limits were 1 × 10−5 mol L−1. Both sensors can be used to determine R-limonene in a concentration range between 1 × 10−5–6 × 10−4 mol L−1 for TPP/AuNPs-S-Gr and 1 × 10−5–1 × 10−3 mol L−1 for Fe(TPFPP)Cl/AuNPs-S-Gr. The highest sensitivity (0.7068 µA/mol L−1) was recorded when the TPP/AuNPs-S-Gr sensor was used, proving that the electrocatalytic effect of this electrocatalyst is higher compared to that of Fe(TPFPP)Cl/AuNPs-S-Gr. High recoveries (values greater than 99.00%) and low RSD values (%) (below 5.00%) were recorded for both sensors when used to determine R-limonene in triple sec liqueur and limoncello.

Fast Response and Low Detection Limit of Ammonia Sensor Based on WO3 Nanoparticles-Decorated BiFeO3 Nanoplates

In this paper, an ammonia sensor based on BiFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composites is presented. BiFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoplates and WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles were prepared by a simple hydrothermal method. The composites were observed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The gas-sensitive properties of the composites and the single material were systematically compared. The experimental results show that the BiFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composites sensor has an excellent response towards ammonia with good long-term stability, short response/recovery time and low detection limit. The gas-sensitive mechanism is further explained that the possible reason for the enhanced gas-sensitive performance is the formation of n-n heterojunctions between BiFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoplates and WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles. The BiFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composites were shown to be a potential room temperature ammonia sensing material.

Silver nanoparticle incorporated colorimetric/fluorescence sensor for sub-ppb detection of mercury ion via plasmon-enhanced fluorescence strategy

Mercury released by industrial processes is a global pollution that threatens human health and the environment. In this study, a colorimetric and fluorescence sensor derived from rhodamine 6G thioamide (RS) was synthesized. The sensor displayed “turn on” fluorescence signaling with the detection limit of 0.49 ppb and the chromogenic change from colorless to pink upon selective sensing of mercury ion (Hg2+). In addition, utilizing plasmonic enhancement by incorporation of RS with the synthesized blue silver nanoparticle (B-AgNPs) to obtain RS + B-AgNPs led to larger emissive fluorescence quantum yield via non–radiative energy transfer, which consequently improved sensitivity of the sensor. RS + B-AgNPs provided approximated 16 times lower detection limit (0.030 ppb) compared to detection limit of the bare sensor. RS + B-AgNPs could be utilized to monitor contaminated Hg2+ in real samples, such as drinking water and seafood fillets. This result indicates that sensor RS + B-AgNPs can tolerate the interference from matrix of the real samples. Moreover, the paper test strip made from RS also demonstrated qualitative and quantitative screenings of Hg2+ with rapid colorimetric change, which could be clearly observed by naked-eye. All of these capabilities indicate that RS and RS + B-AgNPs are promising options for Hg2+ detection to protect human health and an environmental system from the toxic pollution caused by Hg2+.

Design and optimization of wireless in‐situ sensor coupled with gas–water equilibrators for continuous pCO2 measurement in aquatic environments

AbstractAffordable, highly precise, and accurate CO2 sensor is a prerequisite for more extensive CO2 measurements in various environmental settings, and thus more accurate local and global carbon budgets. Here, we propose the use of an autonomous system for the detection of CO2 concentration (mole fraction), appropriate for inland freshwater and eutrophic coastal environments. We describe the construction of a CO2 sensing device (SIPCO2‐II) using off‐the‐shelf commercial products that integrate wireless communication capability. We also report the proof of concept of two newly designed gas–water equilibrators (GWEs) for in‐situ CO2 monitoring to be used with SIPCO2‐II. The performance of the SIPCO2‐II is evaluated in detail, providing information on the sensor sensitivity, detection limit and stability, and comparing these to a commercially available CO2 analyzer (LGR 915‐0011; Los Gatos Research). Comparison results demonstrate good agreement between the two devices with the root mean square error of 5%. The accuracy and precision of SIPCO2‐II against CO2 reference gases are evaluated and values are within 99–104% recovery and 0.9–3 ppm, respectively. The GWEs which comprised either a semi‐passive floater (free‐drifting float equilibrator; FDFE) or a hybrid showerhead‐marble equilibrator (SME) are tested in the laboratory and in the environment. Overall, the SME outperforms FDFE in terms of response time (4 vs. 16 min). The FDFE can cover larger survey areas with lower cost, due to its semi‐passive feature that allows it to drift with water current. The outcome of our study provides an alternative to budget‐constrained CO2 monitoring regimes without compromising the accuracy and precision of the measurements.

Detection Limits of Tetrapolar Impedance Sensors for Tissue Differentiation.

Cancer recurrence is an important issue in bladder tumor resections, because tissue cannot generously be removed from the thin bladder wall without impacting its functionality. Electrical impedance measurements during an operation aim to support the surgeon in making the decision which tissue areas to preserve, because physiological changes in tissue due to cancerous mutations can be detected by their altered electrical characteristics. This work investigates the detection limits of tetrapolar sensors when the impedance of heterogeneous tissue is measured. To do this, a finite element analysis is carried out where the sensors are placed on a dielectric medium with inclusions of different sizes, conductivity, and locations relative to the sensor. It is shown that a sensor with four electrodes in a square performs poorly in comparison to a sensor where the electrodes are symmetrically shaped as rings around one center electrode. This is mainly due to its enlarged regions of negative sensitivity. Based on the results, a third, optimized sensor geometry is proposed that shows superior performance to the other sensors in terms of geometry factor, sensitivities, and tumor detection. In simulation, it can reliably detect tumors with only half the radius of the sensor surface. Smaller tumor fractions cannot be detected by either sensor.

A Review of Preconcentrator Materials, Flow Regimes and Detection Technologies for Gas Adsorption and Sensing (Adv. Mater. Interfaces 20/2022)

Gas Preconcentrators Gas preconcentrators are used to lower the detection limit of gas sensors. In article number 2200632, Aminur Chowdhury, Tanya Hutter, and co-workers review the progress in gas preconcentrators focusing on porous materials. Detection technologies, integration, current limitations and improvement opportunities are also presented.

High-sensitivity amperometric hydrazine sensor based on AuNPs decorated with hollow-structured copper molybdenum sulfide nanomaterials

Hollow-structured hybrid nanomaterials were superior electrocatalysts on account of their unique structures and preeminent properties. This study showed the synthesis of Au decorated with hollow-structured Cu2MoS4 (H-CMS) nanohybrid via hydrothermal and chemical reduction methods. Furthermore, novel hydrazine (N2H4) electrochemical sensor was fabricated based on the as-prepared nanocomposites. The characterization results revealed that homogeneous AuNPs with an average diameter of 13 nm were anchored on the surface and internal cavity of hollow CMS spheres. In addition, the sensor exhibited some excellent electrochemical performance for N2H4 detection. The linear range obtained by the as-proposed sensor was 0.02–377.7 μM, a much lower detection limit with 7 nM (S/N＝3), and a higher sensitivity with 440.1 μA mM−1 cm−2. The linear range of the sensor was maintained at the same level as the widest or better in some cases compared with the similar type of N2H4 sensors previously reported. At least two orders of magnitude reduced the detection limit of the as-proposed sensor. It was about 21-fold lower than that of the TiO2 @PANI@Au/glassy carbon electrode (GCE) sensor with the lowest detection limit. A factor of 1.5 times improved the sensitivity compared with the analogous type Au-Fe3O4-GO/GCE sensor. Additionally, the Au/H-CMS/GCE sensor displayed fast responses, high selectivity, and superior stability for N2H4 detection.

A Review of Preconcentrator Materials, Flow Regimes and Detection Technologies for Gas Adsorption and Sensing

AbstractA preconcentrator is a device used to lower the detection limit of a gas sensor, often integrated upstream of the sensor. Gas preconcentrators have attracted great research interest because of their wide range applications including atmospheric pollution detection, breath analysis, and homeland security. Nanoporous materials, such as carbonaceous adsorbents, metal‐organic frameworks, metallic adsorbents, and oxides, are used to preconcentrate gases for improving detection capability. In this review, preconcentrator materials, detection technologies, and integration with detector configurations are surveyed. Current limitations and future improvement opportunities are also discussed.

Selective visual detection of histamine and ascorbic acid through the rapid gel-sol transition of luminescent alginate hydrogel

A fluorescent hydrogel has been synthesized by crosslinking sodium alginate with Ni2+ in the presence of PEI-derived carbon dots. Such a hydrogel shows a quick selective visual response towards histamine through rapid gel-to-sol transition followed by the release of CD into the sol solution. The amount of histamine can be quantified by measuring the fluorescence intensity of sol solution at an excitation wavelength3 360 nm. The sensor's detection limit in the turn-on intensity mode goes up to 0.63 nM. Utilizing the detoxification reaction of histamine by ascorbic acid, the present sensing platform has been explored to detect ascorbic acid. Due to low-cost and easy synthesis, such hydrogel-based fluorescent chemosensors are potentially suitable for monitoring histamine in serum and fish samples.

Satellites quantify the spatial extent of cyanobacterial blooms across the United States at multiple scales

Previous studies indicate that cyanobacterial harmful algal bloom (cyanoHAB) frequency, extent, and magnitude have increased globally over the past few decades. However, little quantitative capability is available to assess these metrics of cyanoHABs across broad geographic scales and at regular intervals. Here, the spatial extent was quantified from a cyanobacteria algorithm applied to two European Space Agency satellite platforms—the MEdium Resolution Imaging Spectrometer (MERIS) onboard Envisat and the Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3. CyanoHAB spatial extent was defined for each geographic area as the percentage of valid satellite pixels that exhibited cyanobacteria above the detection limit of the satellite sensor. This study quantified cyanoHAB spatial extent for over 2,000 large lakes and reservoirs across the contiguous United States (CONUS) during two time periods: 2008–2011 via MERIS and 2017–2020 via OLCI when cloud-, ice-, and snow-free imagery was available. Approximately 56% of resolvable lakes were glaciated, 13% were headwater, isolated, or terminal lakes, and the rest were primarily drainage lakes. Results were summarized at national-, regional-, state-, and lake-scales, where regions were defined as nine climate regions which represent climatically consistent states. As measured by satellite, changes in national cyanoHAB extent did have a strong increase of 6.9% from 2017 to 2020 (|Kendall’s tau (τ)| = 0.56; gamma (γ) = 2.87 years), but had negligible change (|τ| = 0.03) from 2008 to 2011. Two of the nine regions had moderate (0.3 ≤ |τ| < 0.5) increases in spatial extent from 2017 to 2020, and eight of nine regions had negligible (|τ| < 0.2) change from 2008 to 2011. Twelve states had a strong or moderate increase from 2017 to 2020 (|τ| ≥ 0.3), while only one state had a moderate increase and two states had a moderate decrease from 2008 to 2011. A decrease, or no change, in cyanoHAB spatial extent did not indicate a lack of issues related to cyanoHABs. Sensitivity results of randomly omitted daily CONUS scenes confirm that even with reduced data availability during a short four-year temporal assessment, the direction and strength of the changes in spatial extent remained consistent. We present the first set of national maps of lake cyanoHAB spatial extent across CONUS and demonstrate an approach for quantifying past and future changes at multiple spatial scales. Results presented here provide water quality managers information regarding current cyanoHAB spatial extent and quantify rates of change.

Receptor free fluorescent and colorimetric sensors for solution and vapor phase detection of hazardous pollutant nitrobenzene; a new structural approach to design AIEE active and piezofluorochromic sensors

Two new AIEE active fluorenes 2 and 3 were synthesized via a Suzuki coupling reaction. Sensors, that are free from any receptor showed highly selective detection of active hazardous material, nitrobenzene (NB) in solution and vapor phase based on fluorescence quenching response. The highly selective fluorescence detection of NB was attributed to the adjustable smaller size of NB that eases it to penetrate the cavities of sensors. The fluorescence based detection limits (LOD) of sensors 2 and 3 were determined as 1.21 nM and 1.55 nM, respectively. To the best of our knowledge, these are the first receptor free fluorescent sensors that are used for the convenient detection of NB both in solution and vapor phase. Possible interaction between sensor and NB was evaluated through 1H NMR titration, dynamic light scattering (DLS), and computational methodologies. Moreover, sensors displayed highly selective colorimetric detection of NB that was successfully recorded through the smartphone-based application (Color Assist). Contact mode detection of NB was accomplished through economical and portable test strips. Sensors were also used for the detection of NB in industrial samples. Additionally, sensors possess distinct solvatochromic, piezofluorochromic characters and were used as fluorescent ink that provides them additional advantages.

Point-of-use printed nitrate sensor with desalination units.

Nitrate is an important marker of water quality that can be challenging to detect in seawater due to the presence of multiple chemical interferants and high background chloride. Here, we demonstrate a compact microfluidic device that incorporates electrochemical desalination to selectively remove the interfering chloride ions and improve the detection limit of the downstream potentiometric nitrate sensor. The microfluidic platform was fabricated by a low-cost cut-and-lamination approach, and the detection mechanism was based on potentiometric measurements at an Ag/AgCl electrode coated with a nitrate-selective membrane. The sensor system achieved a detection limit of 0.5mM with a sensitivity of 11.3mV/dec under continuous flow.

Superior sensitivity and low detection limit of NO2 sensor based on layered tungsten oxide

In this study, well-designed layer-like WO3 was synthesized by a facile hydrothermal route. Different characterization techniques have been conducted to comprehensively investigate the properties of morphology and structure of WO3-based sensing materials. The resultant consequences demonstrated that the layer-like WO3 with abundant mesoporous structure displayed higher specific surface area with respect to the pristine WO3 nanoplates. For the first time, the excellent gas sensing device based on layer-like WO3 was constructed successfully, which achieved an admirable gas-sensing response of 106 towards 5 ppm nitrogen dioxide gas at the working temperature of 160 ℃, with a favorable selectivity, and the lowest detection limit was reached to 0.243 ppb. Moreover, the layer-like WO3 sensor possessed considerable reproducibility and stability even in aging tests for 30 days. Those results can be ascribed to this promising structure optimization, which not only provides more reaction active sites but also promoted the gas sensing reaction procedure. Undoubtedly, this work is believed to be useful to offer a feasible strategy to enhance NO2 gas response in practical application.

Intensity-modulated carbon monoxide gas sensor based on cerium dioxide-coated thin-core-fiber Mach-Zehnder interferometer

A novel optic-fiber intensity-modulated carbon monoxide (CO) gas sensor based on cerium dioxide (CeO2) sensing film which coated thin-core fiber (TCF) was proposed and fabricated. Single-mode fiber (SMF), no-core fiber (NCF) and TCF are symmetrically spliced to form a SMF-NCF-TCF-NCF-SMF Mach-Zehnder interference structure. The crystal structure, surface morphology and composition of CeO2 sensing membrane have been characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, high resolution transmission electron microscopy, high-angle annular dark-field and energy dispersive spectrum. The sensing film with the porous appearance can be successfully achieved by the hydrothermal reaction and dip-coating method. While the CO concentration is ranging from 0 to 70 ppm, the sensitivity and detection limit of the optic-fiber CO gas sensor are, respectively, 0.03224 dB/ppm and 0.07630 ppm, and it has a good linearity (0.99127) and almost insensitive to temperature. The response time and recovery time are about 40 s and 47 s, respectively. The surface adsorption and desorption sensing mechanism has been discussed in detail. In addition, CO can be detected by the sensor with unexceptionable selectivity, which has also been verified by the surface adsorption energy results between CeO2 and seven gases, i.e., oxygen (O2), carbon dioxide (CO2), argon (Ar), ammonia (NH3), nitrogen (N2), hydrogen sulfide (H2S) and carbon monoxide (CO). This sensor is simple in structure, and easy to manufacture. It has a good application prospect in the toxic CO monitoring.

Current status of electrochemical detection of sunset yellow based on bibliometrics

Sunset yellow is a synthetic azo colorant widely used in food and beverages. Excessive consumption of sunset yellow can lead to health risks, so it is necessary to establish an efficient and low-cost test. Electrochemical sensor has become a potential analytical method because of its high sensitivity and rapidity. Due to the rapid development of materials science, the detection limit of electrochemical sensors has been further reduced. In this work, we use two bibliometrics software to analyze the topic of electrochemical detection of sunset yellow. A total of 194 papers participated in the bibliometrics analysis. The country, institution and year in which the paper was published were analyzed to understand the cooperation model and development history of the topic. At the same time, this work also analyzes the keywords and categories of the paper. The research directions and hot spots in different stages of this topic are discussed. Finally, we summarized and proposed perspectives of this topic through bibliometrics results.

Optimizing and Quantifying Gold Nanospheres Based on LSPR Label-Free Biosensor for Dengue Diagnosis

The localized surface plasmon resonance (LSPR) due to light–particle interaction and its dependence on the surrounding medium have been widely manipulated for sensing applications. The sensing efficiency is governed by the refractive index-based sensitivity () and the full width half maximum (FWHM) of the LSPR spectra. Thereby, a sensor with high precision must possess both requisites: an effective and a narrow FWHM of plasmon spectrum. Moreover, complex nanostructures are used for molecular sensing applications due to their good values but without considering the wide-band nature of the LSPR spectrum, which decreases the detection limit of the plasmonic sensor. In this article, a novel, facile and label-free solution-based LSPR immunosensor was elaborated based upon LSPR features such as extinction spectrum and localized field enhancement. We used a 3D full-wave field analysis to evaluate the optical properties and to optimize the appropriate size of spherical-shaped gold nanoparticles (Au NPs). We found a change in Au NPs’ radius from 5 nm to 50 nm, and an increase in spectral resonance peak depicted as a red-shift from 520 nm to 552 nm. Using this fact, important parameters that can be attributed to the LSPR sensor performance, namely the molecular sensitivity, FWHM, , and figure of merit (FoM), were evaluated. Moreover, computational simulations were used to assess the optimized size (radius = 30 nm) of Au NPs with high FoM (2.3) and sharp FWHM (44 nm). On the evaluation of the platform as a label-free molecular sensor, Campbell’s model was performed, indicating an effective peak shift in the adsorption of the dielectric layer around the Au NP surface. For practical realization, we present an LSPR sensor platform for the identification of dengue NS1 antigens. The results present the system’s ability to identify dengue NS1 antigen concentrations with the limit of quantification measured to be 0.07 μg/mL (1.50 nM), evidence that the optimization approach used for the solution-based LSPR sensor provides a new paradigm for engineering immunosensor platforms.

Development of paper-based DNA sensor for detection of O. tsutsugamushi using sustainable GQDs@AuNPs nanocomposite

The graphene quantum dots (GQDs) was synthesized using potato starch and water by hydrothermal method and further used for reduction of tetracholoroauric acid to form graphene quantum dots-gold (GQDs@AuNPs) nanocomposite. The GQDs/GQDs@AuNPs were analyzed using FTIR, UV–Vis, Flourometry and HR-TEM. The synthesized GQDs@AuNPs were further used for fabrication of cost-effective screen-printed paper electrode (SPPE) based DNA sensor for the detection of O. tsutsugamushi using htrA gene specific 5′NH2 linked DNA probe. Modification of SPPE using GQDs@AuNPs nanocomposite and ssDNA probe was monitored using EIS, FTIR, FE-SEM and AFM. The sensor detection limit (LOD) was assessed as 0.002 ng/μl from the standard calibration curve with the correlation coefficient, R2 = 0.993. The sensitivity of the DNA sensor was calculated as 7700 μA/cm2/ng for ssGDNA of O. tsutsugamushi using cyclic voltammetry. The sensor validation was done using scrub typhus patient's blood DNA samples. The sensor showed good storage stability at 4 °C for six months with just a loss of 12% of the initial current values. The SPPE/DNA sensor developed is very specific, sensitive, stable and detects O. tsutsugamushi in less time.

High sensitivity and low detection limit of acetone sensor based on Ru-doped Co3O4 flower-like hollow microspheres

In this paper, we successfully prepared Ru-doped Co3O4 flower-like hollow microspheres by a simple hydrothermal method. The microstructure characterization results indicated the formation of well-organized microflowers with a size of 0.5–1 µm, which were composed of nanosheets. The gas sensing performances of sensors by using the synthesized Ru-doped Co3O4 hollow microflowers as sensing material were investigated. The 1 at% Ru-doped Co3O4 sensor showed the best acetone sensing performance and had a response 18.8–10 ppm acetone, which was almost 5.4 times that of pure Co3O4. Significantly, the sensor had an ultra-low detection limit, with a response value of 1.5–50 ppb acetone at 137.5 °C (30%RH). We propose a plausible mechanism for sensing performance improvement. Namely, the substitution of Ru4+ regulated the carrier concentration and induced the change of Co3O4 defect oxygen and chemisorbed oxygen.