Reduced Graphene Oxide Sensor Research Articles

Fast and green synthesis of iron oxide using low-power laser sintering on reduced graphene oxide sensor for ammonia gas detection

Oxide materials are important for gas sensing applications. Unfortunately, most of the synthesis methods use many toxic chemicals and need long calcination at high temperatures. Thus, developing simple and green synthesis processes, which can be performed fast and at low temperatures, is imperative for both industrial manufacturers and our environment. Here, our fast and green synthesis method based on low-power laser sintering for producing FeOx (with Fe2O3 as the main composition) is presented. Besides, FeOx particles were decorated on reduced graphene oxide (RGO) to form a resistive sensor. Notably, our FeOx material can reduce the response of RGO toward acidic gas (NO2) but it enhances the RGO response toward the basic NH3 gas. Particularly, our hybrid FeOx/RGO sensor can detect NH3 gas at above 2 ppm under dry and humidified conditions (<85 % RH). That effect of FeOx is found due to the formation of alpha-phase Fe2O3 which acts as a p-type semiconductor, which is explored and explained in the discussion section. Finally, our findings not only reveal the potential of our hybrid sensing materials for practical NH3 sensing applications but also confirm the usefulness of laser-sintering to produce catalytic oxide materials environmentally friendly and at low cost.

Electrochemical Behavior of β-Cyclodextrin-Ni-MOF-74/Reduced Graphene Oxide Sensors for the Ultrasensitive Detection of Rutin.

Rutin, as a biological flavonoid glycoside, has very important medicinal value. The accurate and rapid detection of rutin is of great significance. Herein, an ultrasensitive electrochemical rutin sensor based on β-cyclodextrin metal-organic framework/reduced graphene oxide (β-CD-Ni-MOF-74/rGO) was constructed. The obtained β-CD-Ni-MOF-74 was characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption and desorption. The β-CD-Ni-MOF-74/rGO presented good electrochemical properties benefiting from the large specific surface area and good adsorption enrichment effect of β-CD-Ni-MOF-74 and the good conductivity of rGO. Under optimal conditions for the detection of rutin, the β-CD-Ni-MOF-74/rGO/GCE showed a wider linear range (0.06-1.0 μM) and lower detection limit (LOD, 0.68 nM, (S/N = 3)). Furthermore, the sensor shows good accuracy and stability for the detection of rutin in actual samples.

Comparative investigation of gas sensing performance of liquefied petroleum gas using green reduced graphene oxide-based sensors.

Herein, we report the comparative gas sensing performance (at room temperature) of reduced graphene oxide sensors obtained by reducing graphene oxide using extracts of pumpkin leaf, neem leaf and methionine. An interdigitated pattern was designed on soda-lime glass using a stamp method and the dispersed solution of rGO was spin coated on the pattern. The electrical response of the sensors was investigated (using a simple in-house measurement set up) by measuring change in resistance of graphene with varying gas concentration on exposure to liquefied petroleum gas (LPG). From the characterization results using FTIR, SEM, EDX and UV-Visible, methionine reduced graphene oxide (MRGO 12H) indicated a greater degree of reduction compared to pumpkin reduced graphene oxide (PRGO 12H) and neem reduced graphene oxide (NRGO 12H). The LPG sensing results showed an increase in the resistance of the sensor materials upon the introduction of the gas and, an increased sensitivity as the concentration of the test gas increased from 100 ppm to 200 ppm while the MRGO 12H sensor was more selective towards LPG sensing. Furthermore, it was observed that the sensor response for the fabricated sensors is strongly dependent on the concentration of gas exposed to the sensors and the degree of removal of oxygen functional groups in the graphene-based materials. Hence, the MRGO 12H sensor had a sensor response of 23.58% at 200 ppm. PRGO 12H at 100 ppm illustrates the least sensor response while NRGO 12H showed very poor sensor response that ranged between 5.10% and 7.56%. The sensor response of the materials demonstrates an improvement in results obtained for pure rGO based sensors. We obtained a response time as low as 5.3 seconds for MRGO 12H while the recovery time of the sensors ranged between 6.46 seconds and 41.50 seconds. The MRGO 12H sensor typified the best recovery time and thus outperformed results from most of the reported literature. Considering different performance metrics such as sensor response, response time, recovery time and sensing period, MRGO 12H is more selective towards detecting LPG. Our results showed that a greater restoration of the sp2 carbon chain brought about by increased reduction of graphene oxide is largely responsible for the sensing behavior of rGO towards LPG.

(Digital Presentation) Flexible Electrochemically Reduced Graphene Oxide Sensors for Lead and Cadmium Detection

Electrochemically reduced graphene oxide (ERGO) is an excellent sensor material for toxic heavy metal ion detection due to its unique properties. The ERGO combines the conductivity of pristine graphene with oxygen-containing defects that provide active binding sites for ions such as Pb2+ and Cd2+. Sensors can be fabricated directly via electrochemical reduction from graphene oxide (GO) solution. This GO solution can be prepared in bulk by the Hummers method. The ERGO layer thickness can easily be controlled by changing the process parameters during the electrochemical deposition cycle. It can be easily deposited on substrates with varying degree of conductivity including glassy carbon, indium tin oxide on glass, carbon paper, carbon cloth etc. The carbon cloth substrate is particularly interesting in that it is flexible, three-dimensional, conductive and inexpensive. The combination of carbon cloth and ERGO form a sensitive and disposable solution to the simultaneous electrochemical detection of Pb2+ and Cd2+. By using differential pulse anodic stripping voltammetry, ERGO on glassy carbon can detect down to 50 nM of Pb2+ and 100 nM of Cd2+, and could resolve simultaneous oxidation peaks for both ion species. Furthermore, the ERGO-carbon cloth sensor shows vastly improved current response compared to the glassy carbon substrate due to the cloth’s 3D nature and high surface area combined with ERGO’s affinity for heavy metal ions. Therefore, electrochemically reduced graphene oxide and carbon cloth form a promising material combination for heavy metal sensing in water and food products.

Stability-improved reduced graphene oxide sensors via resistance initialization of laser irradiation for temperature and gas sensing

Stability-improved reduced graphene oxide sensors via resistance initialization of laser irradiation for temperature and gas sensing

Lignosulfonate in situ-modified reduced graphene oxide biosensors for the electrochemical detection of dopamine.

Lignosulfonate (LS), a biomass by-product from sulfite pulping and the paper-making industry, which has many excellent characteristics, such as renewable, environmentally friendly, amphiphilic nature, and especially the abundant content of hydrophilic functional groups in its architecture, making it highly reactive and can be used as a sensitive material in sensors to show changes in electrical signals. Herein, we report a one-step in situ method to fabricate lignosulfonate-modified reduced graphene oxide (LS-rGO) green biosensors, which can be used for the sensitive electrochemical detection of dopamine without interference from uric acid and ascorbic acid. The modified LS molecular layers act as chemical-sensing layers, while the rGO planar sheets function as electric-transmitting layers in the as-assembled dopamine biosensors. After the in situ-decoration of the LS modifier, the sensing performance of LS-rGO for the detection of dopamine was much higher than that of the pure rGO electrode, and the highest current response of the biosensor toward dopamine greatly improved from 11.2 μA to 52.07 μA. The electrochemical sensitivity of the modified biosensor was optimized to be 0.43 μA μM-1, and the detection limit was as low as 0.035 μM with a wide linear range (0.12-100 μM), which is better than that of most previously reported metal- and organic-based modified graphene electrodes. The newly designed biosensor has unique advantages including rapid, stable, sensitive and selective detection of dopamine without interference, providing a facile pathway for the synthesis of green resource-derived sensing materials instead of the traditional toxic and expensive modifiers.

Gold particles decorated reduced graphene oxide for low level mercury vapor detection with rapid response at room temperature

Rapid and sensitive detection of mercury vapor is of great significance for environmental protection and human health. But the detection method enabling low detection limitation and rapid response at room temperature simultaneously has rarely been reported. In this work, we propose a gold particles decorated reduced graphene oxide sensor for mercury vapor detection. After adding the gold particles, the reduced graphene oxide sensors’ response sensitivity increase by more than 16 times and the response time significantly decreases, which is far less below the results reported by others. The sensor performance improvement should attribute to the distribution of the decorated gold particles, which insert into the layered graphene sheets, as demonstrated by the SEM and XRD results. The increased layer spacing of graphene sheets is conductive to the faster entry/exit of mercury vapor and increases the effective sensing area of graphene. What’s more, the first-principles calculation results confirm the mercury-philicity of gold particles, which also contributes to the increased sensitivity. We further test more performance of the gold particles decorated reduced graphene oxide sensor to mercury vapor, which shows a linear response, low detection limit and good repeatability. The proposed sensor shows rapid response/recovery (6/8 s), low detection limit (0.01 ng/mL), linear response, good repeatability and room temperature detection simultaneously, which shows great application potential for mercury vapor detection.

Simple and fast batch injection analysis method for monitoring diuron herbicide residues in juice and tap water samples using reduced graphene oxide sensor

In this paper, a new analytical method was developed using batch injection analysis with amperometric detection and reduced graphene oxide modified glassy carbon (GCE/rGO) electrode for the simple, fast, sensitive, and effective diuron (DIU) herbicide determination in tap water and food beverages (whole juice of grape and orange) samples. The GCE/rGO sensor provided a 7.6-fold increase in the DIU electrochemical oxidation current compared to the bare electrode, which resulted in a method with good sensitivity and detectability. The developed method provided important analytical characteristics for the DIU quantification, such as detection limit of 0.36 μmol L−1 (84 μg L-1) below the maximum residual limit of U.S Environmental Agency, linear range from 5 to 50 μmol L-1, good precision (RSD < 3.7 %), and accuracy (recovery levels ranging from 80.8–105.5 %). Furthermore, the minimal sample preparation (simple dilution in the supporting electrolyte) associated with a high analytical frequency (150 analyses per hour) stands out. In this sense, the proposed method proves to be an alternative analytical tool for applications in the environmental and food interest samples analysis.

Voltammetric determination of a fluoroquinolone antibiotic based on multilayer reduced graphene oxide sensor prepared directly, promptly by electrochemically expanding graphite electrode surface

ABSTRACT Ciprofloxacin (Cip), a fluoroquinolone antibiotic, was determined by linear sweep adsorptive stripping voltammetric method using multilayer reduced graphene oxide electrode (m-rGO). The m-rGO electrode was fabricated directly, simply and promptly from graphite platform by potentiostatic technique without further modification. The produced electrode exhibited excellent performance for ciprofloxacin (Cip) determination with a much higher signal of Cip than that on the initial graphite electrode (13.4 times). This dominance of the m-rGO electrode resulted from the large electrochemically active surface area, electrochemical catalysis, suitable functional groups on the electrode surface. Experimental conditions such as the electrode fabrication time, the supporting solution, and accumulation time were optimised to obtain the Cip highest signal. A Cip analytical method established under the optimal conditions had a good linear relationship between the Cip signal with its concentration range from 0.5 to 20 µM (R2 = 0.9953). The method showed a low detection limit (LOD = 0.078 µM), satisfactory reproducibility (RSD = 1.50%), and high accuracy. Cip concentration in a spiked lake water sample determined by the proposed method with acceptable precision (RSD = 5.59%) and trueness (recovery = 94.2–106.3%) was comparable with LC-MS/MS method.

Electrochemical sensor for detection of tryptophan in the milk sample based on MnWO4 nanoplates encapsulated RGO nanocomposite

Tryptophan (TRY) is an essential amino acid associated with neurotransmitters and some particular syndromes. For that reason, the detection of Try levels in the food samples is necessary. In recent years electrochemical sensors exhibit inherent effect to detect the amino acids because it has more benefits such as high sensitivity, simplicity, celerity, and economy compared to other traditional methods. Some bimetal oxides have emerged as good candidates for the trace-level detection of amino acids due to their large surface area and high conductivity. As the carbon-based materials, importantly reduced graphene oxide (RGO) have large surface areas to increase the conductivity of the electrodes. In this present work, we demonstrate the detection of TRY by using an electrochemical sensor based on a bimetal oxide with RGO nanocomposite material. We synthesized a manganese tungstate-nanoplates-encapsulated reduced graphene oxide nanocomposite (MnWO 4 /RGO) using a facile hydrothermal method. Morphological and structural characterization of the nanocomposite MnWO 4 /RGO was performed using various spectroscopic techniques and analytical methods. The resulting MnWO 4 /RGO/GCE could be used for the quick and selective determination of TRY in the presence of other interfering bioanalytes. Under optimum conditions, this electrochemical sensor exhibited maximum performance toward TRY determination with good linearity in a broad linear range of 0.001–120 μM with a remarkable lower detection limit of 4.4 nM. The newly proposed sensor was used for the precise determination of TRY in milk samples with satisfactory results. • MnWO 4 /RGO nanocomposite prepared by the facile hydrothermal route without external reducing agent and surfactants. • MnWO 4 nanoplates encapsulated on RGO nanosheets modified electrode is an efficient nanocatalyst for the detection of Tryptophan. • MnWO 4 /RGO sensor exhibit lower detection limit, wide linear range and good recoveries for Tryptophan in Milk samples.

MXene-Derived TiO2 Nanoparticles Intercalating between RGO Nanosheets: An Assembly for Highly Sensitive Gas Detection.

Tight stacking between two-dimensional (2D) sheet-like materials, such as graphene, in the solid state is a major challenge hindering their applications, especially in the gas sensing field. Here, we report on a TiO2 nanoparticle-spaced reduced graphene oxide (RGO) assembly for the design of highly sensitive gas sensors. The TiO2 nanospacers are derived from a 2D MXene that is intercalated between RGO sheets. The produced TiO2-spaced RGO assembly exhibits a uniform nanoparticle distribution and highly wrinkled RGO sheets that interconnect in micrometer-scale pores. The space limitation between adjacent RGO sheets can restrict the particle growth and lead to the formation of TiO2 nanoparticles with uniform diameters of ca. 6.2 nm. The sensitivity of the TiO2-spaced RGO sensor to NO2 improved by over 400% in comparison with pure RGO due to the more available surface area and active adsorption sites. Furthermore, fast response and recovery, excellent selectivity and flexibility, and reliable workability in a humid environment (with the relative humidity ranging from 5 to 95%) were also simultaneously achieved, demonstrating great potential for next-generation wearable sensors.

Ammonia Sensing Performance of RGO-Based Chemiresistive Gas Sensor Decorated With Exfoliated MoSe2 Nanosheets

Chemiresistive ammonia gas sensor based on Reduced graphene oxide (RGO) is an excellent alternative for developing low-cost chemiresistive ammonia gas sensors. However, pure RGO based devices have several disadvantages associated with it such as the response of these devices are very low and the response and recovery time is significantly high. In this work, we have demonstrated that loading MoSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanosheets on RGO sheets helps in improving its ammonia sensing capabilities significantly. The RGO/MoSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanocomposite showed limit of detection down to 300 ppb, whereas, pure RGO based sensor couldn't reliably measure concentration below 1 ppm. The responsivity of nanocomposite-based sensor was 2.6 times better compared to pure RGO sensor. The sensor device could be operated at room temperature with an operating voltage of 2 mV, which demonstrated ultra-low power consumption compared to other commercially available metal oxide Taguchi sensors or electrochemical sensors. A sensing mechanism based on charge transfer is proposed to elucidate the better performance for the device.

Use of reduced graphene oxide for sensitive determination of sulfanilamide in synthetic biological fluids and environmental samples by batch injection analysis

In this work, a reduced graphene oxide sensor associated to the batch injection analysis system with amperometric detection was investigated for the simple, fast and sensitive monitoring of sulfanilamide in lake water and synthetic biological fluid (saliva, sweat and urine) samples. The modified sensor showed a potential displacement of 170 mV and an increase in peak current of 5.5-fold for the electrochemical oxidation of sulfanilamide in comparison to the bare electrode, resulting in a highly sensitive and selective method. Besides, the developed method showed excellent analytical performance with a limit of detection of 2.30 µmol L−1, linear range from 10 to 50 µmol L−1, relative standard deviation below 5.6%, and recovery ranges varying from 83 to 109% for the analysis of spiked samples. In addition, the minimum sample preparation (simple dilution) combined with a high analytical frequency (130 analyses per hour) can be highlighted. Thus, the proposed method demonstrates to be a promising analytical tool for the implementation in routine analysis of clinical interest and environmental monitoring in loco.

Adsorptive stripping voltammetric determination of chloramphenicol residues in milk samples using reduced graphene oxide sensor.

In this paper, the electrochemical response of chloramphenicol (CHL) was investigated on a bare glassy carbon electrode (GCE) and after modification with reduced graphene oxide (GCE/rGO). Preliminary studies by cyclic voltammetry demonstrated an adsorption-controlled mass transport regime of CHL species and a pH-dependent behavior on both electrode surfaces. An adsorptive stripping differential pulse voltammetry (AdSDPV) method was proposed and under optimized instrumental conditions, a comparison of the analytical characteristics of both sensors was performed. The GCE/rGO sensor showed an increase in sensitivity (10-fold), and an anticipation of the reduction potential (200 mV), compared to the bare electrode, due to the adsorptive character (pre-concentration of the CHL species) and the electrocatalytic effect of the nanomaterial. The method was applied to skimmed and whole milk samples, which were simply diluted (50-fold) in supporting electrolyte. The results by AdSDPV using GCE/rGO showed adequate detectability (0.22 μmol L-1), good precision with a 6% relative standard deviation (RSD) and satisfactory recovery ranging from 93 to 108%. The obtained results were statistically similar (95% confidence level) with those performed through ultra-fast liquid chromatography (UFLC). Furthermore, the sensor showed an improvement in the analytical performance for CHL detection, when compared to other sensors reported in the literature. Therefore, the developed method is reliable and promising for implementation in monitoring CHL residues in milk samples.

Additive Manufacturing of a Flexible Carbon Monoxide Sensor Based on a SnO2-Graphene Nanoink

Carbon monoxide (CO) gas is an odorless toxic combustion product that rapidly accumulates inside ordinary places, causing serious risks to human health. Hence, the quick detection of CO generation is of great interest. To meet this need, high-performance sensing units have been developed and are commercially available, with the vast majority making use of semiconductor transduction media. In this paper, we demonstrate for the first time a fabrication protocol for arrays of printed flexible CO sensors based on a printable semiconductor catalyst-decorated reduced graphene oxide sensor media. These sensors operate at room temperature with a fast response and are deposited using high-throughput printing and coating methods on thin flexible substrates. With the use of a modified solvothermal aerogel process, reduced graphene oxide (rGO) sheets were decorated with tin dioxide (SnO2) nanoscale deposits. X-ray diffraction data were used to show the composition of the material, and high-resolution X-ray photoelectron spectroscopy (XPS) characterization showed the bonding status of the sensing material. Moreover, a very uniform distribution of particles was observed in scanning (SEM) and transmission electron microscopy (TEM) images. For the fabrication of the sensors, silver (Ag) interdigitated electrodes were inkjet-printed from nanoparticle inks on plastic substrates with 100 µm linewidths and then coated with the SnO2-rGO nanocomposite by inkjet or slot-die coating, followed by a thermal treatment to further reduce the rGO. The detection of 50 ppm of CO in nitrogen was demonstrated for the devices with a slot-die coated active layer. A response of 15%, response time of 4.5 s, and recovery time of 12 s were recorded for these printed sensors, which is superior to other previously reported sensors operating at room temperature.

Selective determination of ammonia, ethanol and acetone by reduced graphene oxide based gas sensors at room temperature

This work reports a new technique for the selective determination of three organic vapors– ammonia, ethanol and acetone by employing two resistive sensors. These two resistive sensors are based on reduced graphene oxide (RGO) and RGO– rosebengal (RB) composites. The chemically synthesized RGO and RGO–RB based sensors were tested for four different concentrations of ammonia (400–2800 ppm) and two different concentrations (1000, 2000 ppm) of ethanol and acetone each, at room temperature. The RGO sensor was found to exhibit response of 10.3% to 25.3% to 400–2800 ppm of ammonia, 1.01% to 1.15% to 1000 and 2000 ppm of acetone respectively, and 1.05% to 1.56% to 1000 and 2000 ppm of ethanol respectively. The RGO–RB composite-based sensor exhibited an enhanced response ranging from ~17% to 36.6% for 400–2800 ppm of ammonia, 1.6% to 3.2% for 1000 and 2000 ppm of acetone and 1.1% to 1.7% for 1000 and 2000 ppm of ethanol at room temperature. An algorithm, based on the soft margin classifier was developed to accurately determine the concentrations of all the three organic vapors. The initial 100 s of the response values of both the sensors for all the targeted vapors were considered for this purpose. This resulted into classification of all the concentrations of the three organic vapors much before the full-scale response of the sensors. It is believed that this work will aid in development of portable devices comprising of array of sensors having the capability of determining the vapors and their concentrations accurately.

Direct analysis of ascorbic acid in food beverage samples by flow injection analysis using reduced graphene oxide sensor

In this paper, a simple, sensitive and precise electroanalytical method was developed using flow injection analysis (FIA) with amperometric detection and reduced graphene oxide sensor for ascorbic acid determination in samples of multivitamin beverages, milk, fermented milk, and milk chocolate. The advantages of this sensor include a potential displacement of 450 mV and a 2-fold peak current increase for electrochemical oxidation of ascorbic acid, which resulted in a highly sensitive method. No interference of sample matrix was observed, avoiding solvent extraction procedures (samples were only diluted). The FIA allowed a high analytical frequency, approximately 96 injections per hour, together with adequate detection limit of 4.7 μmol L−1. Good precision (RSD < 7%) and accuracy (recoveries between 91 and 108%) evidenced the robustness of the method. The method was compared with ultra-fast liquid chromatography (UFLC) obtaining statistically similar results (95% confidence level). The ascorbic acid content in samples varied from 0.065 to 2.53 mmol L−1.

Study of Thin Film Cu Nanowire and Reduced Graphene Oxide as A Gas Sensor

Reduced graphene oxide (RGO) has potential as various gas sensors. However, the sensitivity depends on the size of layers and the number of exfoliated planes. We fabricated a gas sensor based on the RGO on top of silver electrode and RGO on top of copper nanowires put on similar electrodes. The graphene oxide (GO) was synthesised using Hummer’s method. It was made into RGO using hydrazine as a reduction media. We constructed the gas sensor on top of silver electrodes. The distance between electrodes was 0.5 mm. The RGO sensor was tested to detect several gases in the resistive mode. We also compared the performance RGO sensor on top of Cu nanowires (CuNWs) with the RGO without the CuNWs. The result indicated that the response was in the order of percent when exposed to different concentrations in the range of 100 ppm and 500 ppm. However, the RGO sensor put on directly on Ag electrodes are more sensitive compared to RGO CuNW-Ag sensor.

Highly repeatable and sensitive three-dimensional γ-Fe2O3@reduced graphene oxide gas sensors by magnetic-field assisted assembly process

Reduced graphene oxide (RGO)/metal oxide hybrids are considered as an ideal candidate for high-performance gas sensors due to their large specific surface areas and heterostructures. However, they usually suffer from the poor and unrepeatable sensing performance due to the sheet stacking of RGO nanosheets and the uncontrollable drop-coating process. In this work, three-dimensional (3D) γ-Fe2O3@GO core-shell hybrids have been synthesized by an electrostatic self-assembly method. The sensing device based on uniform 3D γ-Fe2O3@RGO film can be fabricated using the magnetic-field assisted drop-coating and in-situ thermal reduction. Experimental results show that the as-fabricated 3D γ-Fe2O3@RGO sensor exhibits a good selectivity and high sensitivity of 3.43 toward 50 ppm NO2, which is about 2.5 times higher than that of the pure plane-stacked RGO sensor. The response value is still 1.23 when the NO2 concentration drops down to 100 ppb. The high performance can be attributed to the larger surface area, less agglomeration and the formed heterostructures which significantly promotes charge transfer. Importantly, the magnetic-field assisted drop-coating method results in a good stable and repeatable sensing performance due to the magnetic properties of γ-Fe2O3. The architecture strategy opens a new general route to large-scale practical fabrications of high-performance gas sensors based on RGO/magnetic oxide hybrids.

Square-Wave Voltammetry Determination of Ciprofloxacin in Pharmaceutical Formulations and Milk Using a Reduced Graphene Oxide Sensor

In this paper, a simple, sensitive and precise electroanalytical method was developed using a chemically-reduced graphene-oxide (CRGO)-modified glassy carbon electrode and square wave voltammetry (SWV) for determination of ciprofloxacin in pharmaceutical formulations (tablets) and milk samples. Advantages of this sensor include a potential displacement of 100 mV and a 5-fold current increase for the electrochemical oxidation of ciprofloxacin, which resulted in a highly sensitive sensor, when compared to unmodified electrode. The improved properties of the modified electrode are likely due to the formation of a porous surface evidenced by the change in electrode kinetics (thin-layer diffusion process). The proposed sensor is free from interference of sample matrix (pharmaceutical formulations and low/high-fat milk) avoiding cumbersome processes such as previous separations, solvent extraction, or sample filtration (samples were only diluted in Britton-Robinson buffer solution). The results by SWV showed a limit of detection of 0.21 µmol L-1 (correspondent to 0.069 mg L-1), which is lower than the ones obtained using other carbon-based electrodes, relative standard deviations lower than 12%, and satisfactory recoveries in the range from 84 to 109%. The results obtained were statistically similar (95% confidence level) with those performed through high-performance liquid chromatography (HPLC).