Salt Crystallization Research Articles

Chinese yam-derived aerogel as a versatile platform for efficient freshwater production and pollution remediation

Water scarcity and pollution have become major obstacles to sustainable global development. The development of a versatile platform that can simultaneously produce clean water and remediate pollutants from water is highly desirable but still difficult to realize. Herein, to address this challenge, we have developed a CY@PPy@Ag aerogel with excellent photothermal and photocatalytic capabilities through a freeze-drying process, followed by polypyrrole coating and Ag deposition. The excellent characteristics, including broad-spectrum light absorption (97.2%), localization of converted heat, rapid water transport, and porous open microchannels, enabled it to act as an advanced solar evaporator for efficient and continuous steam generation without salt crystallization. Moreover, the high evaporation rate (1.51 kg m−2 h−1) was maintained even in high concentrations of brine and real seawater. Taking advantage of its enhanced photocatalytic performance, organic dyes in water could be rapidly and completely decomposed by the CY@PPy@Ag aerogel under solar irradiation, and this photodegradation process was significantly accelerated with the help of NaBH4. This work is expected to provide a one-stone-two-birds strategy to simultaneously achieve clean water harvesting and pollution remediation, which holds great promise in the fields of solar energy harvesting, wastewater treatment, and seawater desalination.

Commissioning of a Preheat Strategy of a Molten Salt Test Receiver

Solar power tower plants that are operated with molten salt offer the advantage that the molten salt can be used as a heat transfer medium as well as storage medium. Consequently, solar energy can be stored easily and efficiently in only one loop without transformation losses. Furthermore, by using large-scale storage facilities, almost a 24/7 base load operation is possible. Since the molten salt begin to crystallize at temperature of 238 °C, the absorber tube must be preheated before the plants’ operation can begin. During the preheating a subset of heliostats will be aimed on the receiver surface to ensure a solar flux density that leads to tube temperatures above the solar salt crystallization point. Since the absorber tubes are empty during the preheating, there is a risk of high temperature gradients and transients and thus high thermal stresses that may lead to fatigue damage. To prevent this, a preheating strategy for a molten salt test receiver was developed and tested, taking into account ambient conditions and time. The present work shows the results of the commissioning of the developed preheating strategy and discusses its potential for improvement.

Experimental study of sulfate crystallization damage to glutenite rock in the Maijishan Grottoes

Salt crystallization is one of the most important factors causing weathering in grottoes. Cumulative crystallization of salts causes damage such as flaking and peeling of the rocks and accelerates the weathering processes of the grottoes. The accumulated crystalline salts cause spalling, skinning and other damage and accelerate the weathering process of the grotto rock body. It is necessary to study the existing glutenite rock grottoes. This paper took the glutenite rock of the Maijishan Grottoes as a case study, and Na2SO4 or MgSO4 solutions were applied to glutenite rock specimens subjected to different deterioration cycles. The crystallization patterns of the two different salts and their damage to the glutenite rock were analyzed and studied, the mechanism for salt crystallization damage to the glutenite rock was explored, and the crystallization pressures of the two salts in the glutenite rock were derived with theoretical calculations. The results showed that both Na2SO4 and MgSO4 crystallization damaged the glutenite rock, and the former different sulfate solutions changed at different rates, and the changes in the wave caused faster damage than the latter. The physical indices of the rock samples in the velocities and tensile strengths were consistent. Na2SO4 was mainly accumulated on the surface of the specimen and damaged the glutenite rock centripetally via pulverization and exfoliation. MgSO4 mainly crystallized inside the glutenite rock, which created internal fissures and reduced the strength of the rock. The theoretical maximum crystallization pressures of Na2SO4 and MgSO4 in the glutenite rock specimens reached 33.00 MPa and 9.94 MPa, respectively. This study provides a theoretical basis for studies of salt crystallization in glutenite rock grottoes and provides a method for protecting the stones in cultural heritage sites against weathering.

Study on the coupling mechanism of water-heat-vapor-salt-mechanics in unsaturated freezing sulfate saline soil

Understanding the internal regularity of unsaturated freezing sulfate saline soil is of utmost importance concerning the durability and stability of cold region engineering in sulfate saline soil areas. One-sided freezing experiments were performed on unsaturated sulfate saline soils with varying salt and moisture contents and temperature gradients to investigate the interplay of water-vapor-salt migration, heat transfer, ice-water and water-vapor phase transformations, salt crystallization, and salt-frost heave. This study presented a novel water-heat-vapor-salt-mechanics coupling model that considers water-vapor-salt migration and its feedback on soil deformation. The results signify that the water accumulation at the top surface of unsaturated freezing sulfate saline soil is primarily due to water vapor migration. Water-vapor-salt migration, ice-water phase transition, and salt crystallization form more ice and salt crystals, filling the air-filled pores and causing significant salt-frost heave. Water vapor transfer and accumulation further exacerbate the soil deformation for unsaturated freezing sulfate saline soil. The calculating results agree with the test data and demonstrate the efficacy of the proposed five-field coupling model. These findings hold significant implications for developing practical solutions for mitigating the negative impacts of salt-frost heave induced by water-vapor-salt transfer in unsaturated freezing sulfate saline soil on construction projects.

Application of three‐way mixed multivariate analysis of variance method to detect changes in chromatic coordinates (L*, a*, b*) in building granites

AbstractIn the present work we determined the chromatic coordinates (L*, a*, b*) for three building stones used in the heritage city of Ávila, Spain (World Granite Heritage City, 1988). The stones came from quarries and were subjected to 90 cycles of three types of accelerated ageing processes: (a) freezing/thawing together with cooling/heating (T1); (b) salt crystallisation (T2); and (c) freezing/thawing together with cooling/heating + salt crystallisation (T3). A three‐way mixed MANOVA (multivariate analysis of variance) was applied to the data obtained. Significant variations in the three chromatic coordinates (L*, a*, b*) were observed between the three types of accelerated artificial ageing processes compared to the data obtained from the quarry samples, with a tendency towards darkness (↓L*), redness (↑a*) and much less intensity towards yellowing (↑b*).

DIAGNOSIS OF THE DETERIORATION AND CONSERVATION OF BES POTTERY JAR FROM THE TOMB OF PETAH UMM UYA IN SAQQARA

The purpose of this study was the chemical characterization and conservation of the Bes pottery jar. Pottery jars were important in Egypt from prehistoric times until the end of late history; they had their ideological symbolism and important role in daily life. "Bes" jar is a kind of healing jar, which was known and spread during the end of the New Kingdom and Late Period of ancient Egypt. AutoCAD, digital microscope, and polarized microscope (PLM) were used to clarify the deterioration state of the pottery jar. The XRD method was used to investigate the mineralogical composition of the pottery jar. Besides, the pottery's internal morphology and chemical composition were studied using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The examination revealed that the selected pottery jar exhibited numerous cracks, dust accumulation, salt crystallization, and black spots. PLM showed the presence of several minerals, such as calcite, quartz, biotite, and plagioclase. SEM-EDX analysis revealed high calcium oxide concentrations due to the use of calcium carbonate in the slip layer, besides chloride salts. XRD analysis indicated that quartz was the predominant mineral in all the samples. Additionally, calcite, diopside, anorthite, halite, and dolomite were also detected in varying proportions. The pottery jar underwent various treatments, including mechanical and chemical cleaning. In addition, dental gypsum and grog were used in the completion process. Furthermore, the paraloid B-72 was used to achieve the consolidation process.

Gradient Graphene Spiral Sponges for Efficient Solar Evaporation and Zero Liquid Discharge Desalination with Directional Salt Crystallization.

Solar desalination is a promising strategy to utilize solar energy to purify saline water. However, the accumulation of salt on the solar evaporator surface severely reduces light absorption and evaporation performance. Herein, a simple and eco-friendly method to fabricate a 3D gradient graphene spiral sponge (GGS sponge) is presented that enables high-rate solar evaporation and zero liquid discharge (ZLD) desalination of high-salinity brine. The spiral structure of the GGS sponge enhances energy recovery, while the gradient network structures facilitate radial brine transport and directional salt crystallization, which cooperate to endow the sponge with superior solar evaporation (6.5kgm-2h-1 for 20wt.% brine), efficient salt collection (1.5kgm-2h-1 for 20wt.% brine), ZLD desalination, and long-term durability (continuous 144h in 20wt.% brine). Moreover, the GGS sponge shows an ultrahigh freshwater production rate of 3.1kgm-2h-1 during the outdoor desalination tests. A continuous desalination-irrigation system based on the GGS sponge for crop growth, which has the potential for self-sustainable agriculture in remote areas is demonstrated. This work introduces a novel evaporator design and also provides insight into the structural principles for designing next-generation solar desalination devices that are salt-tolerant and highly efficient.

Covalently doping polyaniline-based photothermal fabric for continuous recovery of salt and freshwater from seawater via solar-driven interfacial evaporation

Herein, we present a new three-step route to prepare a covalently doped polyaniline (PANI) -based photothermal fabric with high evaporation capacity. In which, polyacrylamide (PAM) was covalently grafted onto the cotton yarns coupling with poly(glycidyl methacrylate) via electron beam irradiation induced co-graft polymerization as primary graft layer, while PANI was subsequently grafted onto the primary graft layer in situ, which was pre-functionalized by 2-(4-aminophenyl)ethylamine, as secondary graft layer. It has been found that the PAM-doped PANI-based photothermal fabric achieved high evaporation rate 1.60 kg m−2 h−1 from pure water, 1.54 kg m−2 h−1 from 3.5 wt% NaCl solution, and 1.49 kg m−2 h−1 even in 10 wt% NaCl solution under 1 sun irradiation. Furthermore, the evaporation-induced salt crystallization did not appear on the surface of fabric, but preferentially occurred on the area of supporting platform off the fabric. This characteristic endowed the doped fabric with average recovery rate of freshwater at 1.54 kg m−2 h−1 and salt at 0.03 kg m−2 h−1 from simulated seawater. This work provides a novel strategy to the enhancement of conductive polymer based photothermal materials via covalently doping, which could popularize the application of solar-driven evaporation to resource recovery from saline waters.

Magnesium source with function of slowly releasing Mg and pH control for impurity-resistance synthesis ultra-large struvite from wastewater

Struvite (MgNH4PO4·6H2O, Magnesium ammonium phosphate, MAP), recovered from wastewater, has potential application as a slow-release fertilizer. However, crystal size distribution (CSD) of recovered MAP typically lied in the range of 50–300 μm, due to fast nucleation rate and notably narrow metastable zone width (MSZW) of MAP, with purity levels 40–90 %. In order to control the rate of nucleation, a novel magnesium source with the form of MgHPO4·3H2O wrapped with Mg(OH)2 was prepared, referred to as P-3. This compound gradually released Mg2+ and PO43−, regulating solution concentration kept in MSZW to promote crystal growth. The inherent Mg(OH)2 within P-3 also acted as a pH regulator in wastewater, eliminating the necessity for additional acid or alkali adjustments during crystallization process. The MAP precipitated by P-3 exhibited an impressive CSD of 5000–7000 μm, with a maximum size reaching 10,000 μm. This represented the largest CSD reported in literature for recovered MAP from wastewater. The significance of the ultra-large MAP precipitated by P-3 lied in its enhanced resistance to impurity adsorption, resulting in MAP with a remarkable purity 97 %, under conditions of low heavy metal ion concentration approximately 5 mg/L. Furthermore, the removal efficiency of ammonia nitrogen (NH4+) can reach 92 %. In comparison, two other magnesium sources, soluble salts (MgCl2 and Na2HPO4, P-1) and a combination of insoluble salts (Mg(OH)2 and MgHPO4, P-2) were evaluated alongside P-3. The CSD of MAP precipitated from P-1, P-2 was both <100 μm, with purity levels of 90 and 92 % and NH4+ removal efficiency of 92 and 90 %, respectively. Importantly, the strategy of obtaining ultra-large size MAP from wastewater in this study provided novel insights into the crystallization of other insoluble salts with large sizes.

Study on the multi-field-coupling model of saline frozen soil considering ice and salt crystallization

Sulfate soil, a typical saline soil in Qinghai Tibet Plateau, has the engineering characteristics of salt expansion and frost heave, which are seriously threatening the operation and safety of engineering buildings. Based on the phase diagram theory, we determined the functions of ice and hydrated salt in pore solution under different concentrations and temperatures. Then we further established a multi-field-coupling model of saline frozen soil considering ice and salt crystallization to simulate the water/salt migration process and the deformation law of saline soil in the cooling process. Compared with the results of unidirectional freezing test, we verified the reliability of the model, indicating that the model well reflected the development of water, temperature, salinity, and deformation of saline soil. Finally, we discussed the variation of each component in sodium sulfate soil, the change process of soil hydraulic conductivity, and the deformation mechanism according to the proposed numerical model. The results provide a theoretical reference for the engineering application of a multi-field-coupling model of saline soil in cold regions.

Duckweeds mimicked self-clean Janus solar evaporator

Solar water evaporation has been considered as a promising method to solve the global water scarcity due to its low energy consumption, environmental friendly, as well as high water evaporation efficiency. However, salt crystallization on evaporation surface drastically decrease the evaporation rate of seawater. In this work, we propose a novel bionic solar evaporation system based on 3D printing technology inspired by natural duckweeds. Water can be easily transported to the evaporation surface through regularly arranged “S” shaped microchannels. Superhydrophilic surface enables the water spread quickly on evaporation surface and eventually fall back to bulk water, realizing the self-clean capability. The evaporation rate of our solar evaporation system can reach up to 1.40 kg m−2 h−1 with an evaporation efficiency of 95.7% under 1 sun irradiation. In addition, the evaporator demonstrates amazing desalination and purification capabilities, which can effectively remove metal ions as well as organic impurities with a purification rate up to 99.9%. Moreover, long-term desalination performance of our evaporation system has been well achieved, demonstrating the effective and stable performance of our bionic evaporation system for seawater desalination.

Investigation of the liquid water content in composite saline soil containing chloride and sulfate ions

Different salt types have different effects on the liquid water content of saline soil, resulting in differences in the physico-mechanical properties and water/salt migration process of saline soil. In order to investigate the phase transition process and the change of the liquid water content in composite saline soil, saline soils with the same total salt content and different ratios of sodium chloride and sodium sulfate were taken as the objects. The results indicated that two phase transitions occur in the saline soil with single salt type, while three phase transitions can be found in the composite saline soil with two salt types. Mirabilite crystallization contributes to the 1st phase transition, mirabilite and ice precipitate together in the 2nd phase transition process, and mirabilite, ice, and hydrohalite precipitate simultaneously in the 3rd phase transition process. The liquid water is reduced in the phase transition process during cooling, and the pore characteristic has been changed significantly. The change of the liquid water content reflects the processes of salt crystallization and ice formation in saline soil, then the amounts of ice and hydrated salt were calculated at different temperatures, and the mechanism of inhibiting the deformation of sulfate saline soil was examined by adding sodium chloride. The results have reference value for those seeking understanding of the deformation in natural composite saline soil, and these findings can provide theoretical basis for the phase transition mechanism of saline soil in cold regions.

Ultralight anisotropic Ti3C2Tx MXene/Carbon nanotube hybrid aerogel for highly efficient solar steam generation

Solar steam generation (SSG) has been considered as a promising method to produce fresh water from seawater. Due to high light absorption and excellent chemical stability, carbon nanotube (CNT) has been widely used for SSG. However, it is still challenge to simultaneously realize high water evaporation rate and energy efficiency for CNT based solar steam generator. Herein, ultralight anisotropic Ti3C2Tx MXene/carbon nanotube (A-Ti3C2Tx/CNT) aerogels are designed and fabricated for highly efficient SSG. The combination of CNT and Ti3C2Tx MXene endows the hybrid aerogel with high light absorption and effective localized surface plasmon resonance (LSPR), resuting in enhanced light-to-heat conversion efficiency. The porous structure of aerogel leads to multiple scattering and absorption, further contributing to the photothermal conversion process. Moreover, the low thermal conductivity of aerogel structure effectively reduces the heat loss to environment. Through tailoring the anisotropic channel, the A-Ti3C2Tx/CNT hybrid aerogel with average channel size of 80 μm possesses most efficient water transport due to the capillary effect and formation of intermediate water. Therefore, the A-Ti3C2Tx/CNT hybrid aerogel exhibits high average light absorption of 95.68% in the wavelength range of 200–2500 nm, excellent water evaporation rate of 2.10 kg m−2 h−1 under 1 sun irradiation (1 kW m−2) with a high energy efficiency of 93.4%, and remarkable durability with 7 days continuous water evaporation. The A-Ti3C2Tx/CNT hybrid aerogel also shows high resistance to salt crystallization due to its high salt transport flux of 1.90 kg m−2 h−1. This work offers a prospective strategy for constructing highly efficient solar steam generator with stable performance for practical application in seawater desalination.

Light-assisted patterning of salt precipitation on photovoltaic LiNbO3 substrates

The control of salt crystallization on a surface has important implications in many technological and industrial applications. In this work, we propose and demonstrate an optoelectrical method to define and control the spatial distribution of salt crystallization on a lithium niobate photovoltaic substrate. It is based on the bulk photovoltaic effect that generates an electric field on the illuminated regions of the crystal. The salt only crystallizes on these illuminated regions of the substrate. Single salt spots or more complicated spatial patterns, defined by the light intensity spatial distribution, have been achieved. In particular, some results have been obtained using scanning/moving laser beams, i.e., “drawing” the saline patterns. The role of light exposure time and salt concentration in the aqueous solution has been studied. The method has been checked with several salts with successful results showing its general applicability. A discussion on the possible physical mechanisms behind the method and their implication for the operation of photovoltaic platforms in other applications is also included.

Chitosan-derived carbon aerogel modified with lignin carbon quantum dots for efficient solar evaporation

Solar-powered desalination technology offers outstanding benefits in providing clean, safe water and alleviating global freshwater shortages. However, the low evaporation rate, poor salt resistance and high cost limit the development of solar evaporators. Inspired by plant transpiration, a solar evaporator was fabricated from lignin carbon quantum dots (LCQDs) modified chitosan carbon aerogel (C-LCDCA). The introduced LCQDs and low carbonization temperature (280 °C) ensured hydrophilic properties while maintaining the three-dimensional porous structure, as well as improved light absorption and photothermal conversion properties. The evaporation rate of C-LCDCA under one sun was 1.71 kg m−2h−1. Interestingly, C-LCDCA promoted the local crystallization of salt crystals and realized the collection. The evaporation performance of the evaporator can be adapted to different evaporation situations by making simple layer adjustments. The optimal C-LCDCA evaporator (4-layer integrated) surpassed the limit of the interfacial evaporation system, with evaporation rate and efficiency up to 2.32 kg m−2h−1 and 113.9 % respectively under one sun, and with strong salt-rejecting (no obvious salt crystallization in 20 wt% brine for 8 h) and excellent self-cleaning ability (0.3 g NaCl re-dissolved back to 15 wt% brine in 15 min). With superior evaporation performance, the condensate obtained by the evaporator in simulated seawater evaporation experiments met the World Health Organization’s drinking water standards, and enabled effective treatment of industrial wastewater containing heavy metal ions (Cr3+, Fe3+, Pb2+, and Ni2+), nanoplastics (500 and 50 nm), and dyes (Rhodamine B, Methyl Orange, and Malachite green). These findings provide new ideas for the preparation of efficient, salt-rejecting, self-cleaning, and environmentally friendly solar evaporators and advance the practical application of sustainable water purification technologies.

A multi-layer fabric for high-efficiency solar-driven seawater desalination

Fiber-based photothermal materials for seawater desalination usage have garnered significant attention owing to their outstanding properties. However, traditional monolayer fabrics are prone to possess inherent inefficiencies such as high thermal dissipation and salt crystallization within the evaporation zone, especially reducing the evaporation efficiency during the long-term seawater desalination. Herein, a novel three-layered three-dimensional (3D) spacer carbon/polyester cotton spacer woven fabric (SWF) evaporator is designed. This SWF material was delineated into three distinct layers: an upper evaporate layer, a foundational water absorption layer, and a central water dedicated to water transition, thermal insulation, and salt crystallization. The rational three-layered 3D architecture guarantees the swift aqueous transition within SWF evaporator, simultaneously curtailing thermal losses from the top layer. The evaporation rate of 3D SWF, with 6 mm interval space, registered at 1.6721 kg · m−2·h−1 under a solar intensity of 1 kW · m−2. Furthermore, under conditions with a solar power of 1 kW · m−2 and a wind velocity of 2 m · s−1, the evaporation efficiency of liquid water from SWF, with a central layer height of 12 mm, culminated at 3.9742 kg · m−2·h−1, which validated its adeptness for the seawater desalination applications. The results of our research are helping to provide for efficient and stable methods of wastewater treatment, desalination, and drinking water collection.

Mechanism of Salt Precipitation Blockage in Low-Producing Gas Wells and the Method of Acidification Blockage Removal.

In the Changqing area, over 23.6% of gas wells produce less than 0.1 × 104 m3/d of gas daily, posing a challenge to gas field sustainability. Laboratory analysis of scale samples from three wells and formation water analysis via inductively coupled plasma revealed soluble salt as the primary well blockage, with sodium chloride and calcium chloride comprising 48.0-81.2% of total content. The G3# well blockage contains a small amount of quartz from acid-insoluble components of carbonate acidification. Formation water from all wells exhibited high salinity (up to 153 g/L) with a calcium chloride water type. Scanning electron microscopy and EDS confirmed halite and quartz features in blockage samples. Theoretical calculations show salt crystallization when tubing pressure falls below 10 MPa and daily water production is <1.0 tons/day. Lower production leads to lower tubing pressure and higher salt precipitation at the bottom of the well. For G1# and G2# blockages, HCl dissolves >90%, and water >85%, making them suitable removal agents. For 3# blockage, mud acid with >80% dissolution is recommended. Chemical methods effectively clean the wellbore and formation. Optimized blockage removal measures increase tubing pressure and daily production by 2.18 and 4.05 times, respectively. This study offers insights into addressing well blockage challenges in low-producing gas wells.

Novel strategies for terephthalic acid processing under soft conditions using ionic liquids

Terephthalic acid (H2TPA) solubility in several ionic liquids (ILs) at multiple concentrations is higher than for any other known solvents at lower temperatures and pressures which suggests low energy purification of H2TPA from its major impurity, 4-carboxybenzaldehyde (4-CBA) might be possible. To understand the mechanism several strategies were explored to purify H2TPA by taking advantage of this high solubilizing power of ILs for H2TPA in the crystallization of unique salts and cocrystals. Using either zwitterionic carboxylate IL-precursors or direct salt formation with carboxylate ILs or amines, a series of salts of mono, dibasic and two ionic cocrystals were obtained including monobasic, [C1C1im][HTPA], [N4441][HTPA], [C4C1im][HTPA]•0.5H2TPA (a cocrystal), and [C1Him][HTPA] ([C1C1im]+ = 1,3-dimethylimidazolium, [N4441]+ = tribuytlmethylammonium, [C1Him]+ = 1-methyl-3-H-imidazolium), dibasic [C1C1im]2[TPA], [C4C1im]2[TPA], [N4444]2[TPA], [C1Him]2[TPA], [H2N22]2[TPA], [H3N6]2[TPA], and [HN(CH2CH2OH)3]2[TPA] ([C4C1im]+ = 1-butyl-3-methylimidazolium, [N4444]+ = tetrabuylammonium, [H3N6]+ = hexylammonium, [HN(CH2CH2OH)3]+ = triethanolammonium, [H2N22]+= diethylammonium), and a second cocrystal [C2C1im]Cl•0.5H2TPA. The formation of these salts suggest a viable method to purify H2TPA because of preferred salt formation at low energy conditions. One elegant route using 1-ethyl-3-methylimidazolium chloride ([C2C1im]Cl) could be especially promising because the cocrystal [C2C1im]Cl•0.5H2TPA was readily isolated and is easily dissociated when exposed to ambient conditions into crystalline H2TPA and a liquid of hydrated [C2C1im]Cl.

Temperature and humidity effects on salt crystallization in burnt clay bricks

This study offers an idea of investigating the temperature and humidity effect on salt crystallization in burned clay brick when it is subjected to a saline environment. It has been investigated that salt may be carried into masonry pores structures by moisture. As moisture production and movement are affected by temperature and humidity, the mechanism of salt crystallization is affected as well. Uniaxial Salt crystallization in burned clay bricks at different temperatures (20 °C, 30 °C, and 40 °C) and humidity (70%, 80%, and 90%) has been investigated, considering all other parameters to be constant. Analyzing the data derived from the experiment, two equations have been developed (one for temperature effect analysis and another for humidity effect analysis). Results indicate that the salt crystallization in burned clay bricks increases when the temperature of samples and sodium sulfate (Na2SO4) solution increases. However, the salt crystallization in burned clay bricks goes down when the relative humidity of the surrounding environment of samples decreases.

Role of extrinsic factors on magnetoelastic resonance biosensors sensitivity

Magnetoelastic (ME) resonance devices are attractive for application as biosensors in health-related areas as they allow contactless detection of pathogenic agents with high sensitivity. After functionalization, they offer valuable diagnostic options that promote efficient capture of mass on the sensor surface through biological interactions. ME sensors are also sensitive to external factors such as temperature, magnetic fields, and variations in mass that can arise from processes unrelated to biological interactions, including corrosion and salt crystallization. This article evaluates extrinsic factors that affect the response of ME resonance sensors for diagnostic applications. In particular, the influence of heat treatments, operation temperature, applied DC magnetic field bias, and corrosive environment were studied. The control of all these factors is crucial for the design, fabrication, and functionalization of ME resonance biosensors and for the development of measuring instrumentation and effective measurement protocols. This work established maximum operating temperature and bias field variations to keep the sensor sensitivity. Heat treatment of the sensors before and after coating improved the signal-to-noise ratio and corrosion resistance. Further improvement in corrosion resistance was provided by cathodic protection, which has been proven beneficial for applications of ME resonance sensors in aqueous fluids.