With the constantly deeper understanding of individualized precision therapy, immunotherapy is increasingly developed and personalized. The tumor immune microenvironment (TIME) mainly consists of infiltrating immune cells, neuroendocrine cells, extracellular matrix, lymphatic vessel network, etc. It is the internal environment basis for the survival and development of tumor cells. As a characteristic treatment of traditional Chinese medicine, acupuncture has shown potentially beneficial impacts on TIME. The currently available information demonstrated that acupuncture could regulate the state of immunosuppression through a range of pathways. An effective way to understand the mechanisms of action of acupuncture was to analyze the response following treatment of the immune system. This research reviewed the mechanisms of acupuncture regulating tumor immunological status based on innate and adaptive immunity. The tumor immune microenvironment (TIME) is an important site of interaction between tumors and the human immune system. It mostly consists of tumor cells, immune cells, fibroblasts, endothelial cells, and other cells that provide favorable conditions for tumor proliferation and progression . MoleculBoth modern and traditional medicine are faced with the dilemma of actively exploring new ways to improve the survival time of patients with malignant tumors. Since the concept of comprehensive treatment was promoted, acupuncture was used in the traditional treatment methods owing to its unique advantage. Derived from traditional Chinese medicine (TCM), acupuncture has been inherited and carried forward through accumulated practice . A varieStudies demonstrated that acupuncture improved symptoms through systemic conditioning of meridians and acupoints . It achiThis paper summarized the mechanisms underlying acupuncture-mediated immune regulation from the perspective of innate immunity and adaptive immunity. A better understanding of these mechanisms would provide a scientific basis for the further clinical utilization of acupuncture in the treatment of malignant tumors.As the initial line of body defense, innate immunity is an essential component of the immune system. It is also referred to as nonspecific immunity, which means a type of natural defense that can develop independently of antigen stimulation or develop gradually as a result of long-term ethnic evolution . Innate NK cells are innate lymphocytes that are recognized in various organs . They poThe hypothesis of acupuncture immune enhancement was raised, which considered that acupuncture probably could prevent and kill tumor cells by increasing NK cells . In the Macrophages are the major component of the mononuclear phagocyte system, playing key roles in the innate immune system. They exist various functions and have significant effects on normal homeostasis and disease progression . AccordiRegulating the phagocytic ability of macrophages and the secretion of immune factors were important cellular mechanisms for acupuncture to enhance immunity and treat diverse diseases. Acupuncture promoted the macrophage phenotype and IL-10 expression to mitigate the pain and inflammation of animal muscle. Further study demonstrated that acupuncture modified the macrophage phenotype of inflammatory muscle, and it could be the basic process causing the IL-10-induced analgesic and anti-inflammatory actions . In addiMast cell (MC) is a group of bone marrow-derived immune cells that differentiates and matures in peripheral tissues. MC plays an immunomodulatory role in both innate and acquired immune responses, thus affecting the progression and prognosis of related diseases . The infMicroglia is an important type of innate immune cell in the central nervous system, which is the main effector in the process of inflammation progression . AcupuncNeutrophils, which originate from myeloid precursors, are crucial components of white blood cells and the first responders of the innate immune system against extracellular pathogens and wound healing . Recent + T cells (Dendritic cell (DC) is a rare group of immune cells in tumor tissues, which regulates immune signals by ingesting and presenting antigens to T cells, contacting directly between cells, and providing cytokines . The reg T cells . Under t T cells , 62. TheAdaptive immunity includes T-cell-mediated cellular immunity and B-cell-mediated humoral immunity. The main force involved in anti-tumor adaptive immunity is T lymphocytes, which mainly include CTL and Treg cells . As the Cellular immunity is the main immune response in human autoimmune mechanisms. The immune function of patients with malignant tumors is related to the imbalance of the proportion and quantity of T cells. The T-cell-mediated immune response is characterized by the presence of an inflammatory response dominated by monocyte infiltration and/or specific cytotoxicity. Acupuncture has been confirmed that regulated the differentiation of T-cell subsets and promoted the drift of Th1/Th2 and Th17/Treg toward Th2 and Treg, respectively . Thus, i+ and CD8+ cells were likely responsible for the extended survival time and successful treatment of tumors (+CD4+ and CD3+CD8+ T cells in the EA group were significantly increased (+, CD4+ and CD4+/CD8+ after subtotal gastrectomy (+, CD4+ and CD4+/CD8+ (+, CD4+, CD8+ and CD4+/CD8+ (+, CD8+ and T-cell subsets (As for the treatment of cancer-related diseases, the absolute account of T cell subsets and anti-tumor response were closely related to the prognosis of tumor patients. Preclinical studies demonstrated that more CD4f tumors –77. Addincreased . The anatrectomy . SimilarD4+/CD8+ . As for D4+/CD8+ . Saam ac subsets . In concThe proliferation, differentiation and antibody secretion of B cells are the basic processes of humoral immunity. Acupuncture was demonstrated that had a dual regulatory effect on the production of antibodies by B cells . When imMalignant tumors produce or secrete some immunosuppressive substances to evade the role of the immune system, to expect the normal growth and proliferation of tumor cells . AcupuncDiscussing the relationship and mutual influence of acupuncture on TIME are current research hotspots, but the accuracy, depth and breadth of the research are not enough. From the retrieved literature, most of the mechanism studies were still focused on the mechanism of immune function. Moreover, the research was still based on the dose-effect study of acupuncture on the tumor, and there was little discussion on the internal mechanism and pathway of the tumor. Therefore, the content of this article is both logical and speculative. Future research should explore the mechanism of acupuncture on TIME more deeply from the aspects of signal pathway with modern biology and technology. This will better provide a theoretical basis and standardized treatment for clinical treatment.All authors contributed to the study’s conception and design. Material preparation, paper collection and analysis were performed by FK and NW. The first draft of the manuscript was written by NW and all authors commented on previous versions of the manuscript. All authors contributed to the article and approved the submitted version.


Permanent deformation is one of the dominant asphalt concrete damages. Significant progress has been made to realistically predict the damage. In the last decade, the mechanistic approach has been the focus of research, and the fundamental theories of viscoelasticity, viscoplasticity, continuum mechanics, and micromechanics are applied to develop the material laws (constitutive equations). This paper reviews the advancement of permanent deformation models including analogical, microstructural, and continuum-based methods. Pavement analysis using the nonlinear damage approach (PANDA) is the most comprehensive and theoretically sound approach that is available in the literature. The model coupled different damages and other phenomena . The anisotropic microstructure approach can be incorporated into the PANDA approach for a more realistic prediction. Moreover, the interaction of fatigue and permanent deformation is the gap that is lacking in the literature. The mechanistic approaches have the capacity to couple these damages for unified asphalt concrete damage prediction. HIn a cyclic creep-recovery test, material hardening grows, and the hysteresis loops shift horizontally due to the accumulation of irrecoverable viscoplastic strain (open loops). On the other hand, in the idealized fatigue test (either stress- or strain-controlled), cyclic load is applied that causes stiffness reduction and a phase angle increment with a negligible viscoplastic strain . In simultaneous fatigue-permanent deformation damage, the material hardening contributes to initiate fatigue cracking at intermediate temperatures, and the fatigue cracks accelerate the microstructure change and contribute to viscoplastic deformation. The viscous flow creates a plastic zone (the crack initiation point), and fatigue cracking can evolve without plastic flow (aggregate movement and re-orientation). That means the simultaneous occurrence of the two damages cannot be ignored as they are interdependent. Thus, the hysteresis loops can be modified by superposing the two loops a to accoOne of the limitations for interaction damage modeling is the lack of integrated testing protocol for permanent deformation and fatigue. Some attempts were made, such as Indirect Tension (IDT) testing for deformation and fracture and applying a haversine loading waveform in fatigue tests ,105. TheThe main objective in the design and service life estimation of asphalt concrete is to estimate the number of cycles . Some progresses are being made to transition from empirical to mechanistic-empirical design methods. The primary motivation of this literature study was to explore the advancement of asphalt concrete permanent deformation characterization, constitutive modeling, and application. The current state of research is focused on the formulation of a mechanistic method that applies the fundamental theories of mechanics and materials to predict permanent deformation damage. In the last decade, promising advancements have been made in the development of comprehensive and coupled permanent deformation modeling. Pavement analysis using the nonlinear damage approach  constitutive model is one of the notable progresses that is gaining wide acceptance (as the next generation mechanistic pavement design approach). Another promising area of progress is the microstructural approach aided with 3D digital image analysis equipment and finite element modeling. This digital technology-based permanent deformation modeling is also the future prospect for accurate permanent deformation modeling and prediction of different asphalt mixtures. The mechanistic methods offer unlimited potential to expand the modeling parameters, and different damages and phenomena such as aging, healing, moisture damage, pre-crack, etc., can be coupled to unify damage prediction. The drawbacks of mechanistic models are sophistication, requiring extensive testing, and the calibration of several modeling variables. For example, the viscoelastic–viscoplastic–viscodamage model requires more than 21 model variables to be optimized using at least two different experiments and several test repetitions at different temperatures stresses and strains. The improvement of the latest models from the classic viscoplastic strain hardening model is the consideration of cyclic hardening and relaxation mechanisms and the viscodamage of asphalt concrete. Although the mechanistic method is theoretically appealing, the calibration cost and rigorous equations can be considered the limitations. The micromechanics approach considers the evolution of permanent deformation related to changes in the microstructure of asphalt concrete constituents (aggregates and mastic). Thus, the micromechanics method is regarded as the most realistic way of modeling heterogeneous materials such as asphalt concrete. Based on the extensive literature study, the permanent deformation prediction and modeling approaches can be categorized into four aspects, as shown in A review study was conducted to explore the state of the art on permanent deformation prediction from the 1960s’ pure empirical to latest mechanistic (from 2011) methods. The review study revealed that the latest constitutive models integrate and couple different theories, i.e., continuum mechanics (1958), nonlinear viscoelastic (1969), viscoplasticity (1971), and viscodamage (2011), along with the crucial time–temperature superposition principle. Such coupling techniques offered advantages of integrating different asphalt concrete damages and opened the possibility of a unified asphalt damage model in the future. The PANDA model is one of the most comprehensive permanent deformation modeling approaches available in the literature . The calibration and/or validation tests are reliant upon the conventional creep or creep-recovery tests in either confined or unconfined modes. The computation and experiment cost of mechanistic methods are the limitations. The practical application of the mechanistic models is very limited at the moment. Moreover, the fatigue–permanent deformation (rutting) interaction is often ignored in the existing (studied) literature. It is inferred that both damages can evolve simultaneously as the same load caused both damages. The mechanistic approach has the potential to couple the two predominant pavement damages. From the extensive study, it can be synthesized that a unified permanent deformation damage model can be developed by integrating continuum damage and microstructure approaches and coupling fatigue, moisture, healing, aging, and other physical and chemical phenomena in asphalt concrete.The mechanistic method is “universally” applicable to predict damage regardless of climatic conditions, stress state, or material type. This characteristic presents wide, open research questions, for example, (1) developing a unified pavement damage performance prediction model, (2) a coupled model for fatigue and rutting damages using continuum mechanics and viscoelastic and viscoplastic theories, (3) considering (coupling) different strains such as shear and axial strains in permanent deformation prediction models, and (4) developing simplified (unified) asphalt concrete test methods to characterized different damages simultaneously . The authors of this paper are conducting research on the simultaneous creep–fatigue damage evolution in a sequential manner.


Measures to which a person resits and/or does not provide consent for are defined as involuntary treatment. The use of involuntary treatment violates the autonomy of (older) persons and causes more harm than benefit. Moreover, it contradicts the values of person-centred care. Nevertheless, its use among Persons Living with Dementia (PLWD) is still common practice and remains difficult to prevent and/or reduce. The aim of this study was to gain insights into the barriers towards the prevention and/or reduction of involuntary treatment in long-term geriatric care. We conducted a cross-sectional, mixed-methods study, including an online survey for professional caregivers, and a semi-structured focus group interview with professional caregivers. A total of 218 participants completed the questionnaire. The percentage of participants that experienced barriers in one of the twenty-two survey items ranged from 15% to 42%. Lack of time; the experienced need to use involuntary treatment; uncertainty about responsibilities of stakeholders; and a lack of knowledge on methods to prevent and/or reduce its use were most seen as barriers. Nursing staff experienced a lack of time more often than other professional caregivers. Working in home care and having no former experience with involuntary treatment usage increased perceived barriers. Participants of the focus group interview confirmed these findings. One out of four professional caregivers experience barriers hindering prevention and/or reduction of involuntary treatment. More research is needed to gain better understanding on how professional caregivers can be supported aiming to, remove barriers and consequently prevent and/or reduce the use of involuntary treatment.


The stratum corneum is the outermost layer of the epidermis. It acts as an interface with the external environment and functions as a barrier that prevents microorganisms and allergens from penetrating the skin, while preventing bodily fluids, electrolytes and proteins from being lost in a process aimed at maintaining homeostasis. With the novel coronavirus disease 2019 (COVID-19) outbreak, there has been an increase in hygiene practice, particularly hand washing and the use of hand sanitisers. These practices have undoubtedly assisted a great deal in combatting the rate of transmission and contributed immensely to saving lives. However, repeated hand washing and the use of sanitisers have both been linked with marked skin dryness and contact dermatitis. This especially holds true when the above-mentioned practices are carried out in the absence of intermittent hand moisturiser usage. Hand hygiene is a widely accepted principle in the prevention of disease transmission because proper hand hygiene has a 24% to 31% likelihood of decreasing the spread of transmissible disease.5Hand hygiene products are available in a variety of forms, and while each of these formulations may be effective against COVID-19, they may also alter skin barrier integrity and function. Alcohol-based hand sanitisers with moisturisers have the least sensitising and irritancy potential when compared to soaps and synthetic detergents.As an additional measure to social distancing and all the recommended measures by authorities, most healthcare workers and the general public became engaged in repetitive and aggressive hand sanitising and hand washing practice.Sanitising, hand washing and the frequent use of soaps remain effective in killing the novel coronavirus and thus delay the spread .6However, research has shown that not many people use emollients congruent with the increased sanitising and copious hand washing practices.6Hand washing, especially with hot water has been directly linked to skin dryness (xerosis), through transcutaneous water loss see .67The use of sanitisers, especially the alcohol-based types, is strongly associated with skin moisture loss and irritant contact dermatitis due to their harshness on the skin. This is due to the negative effect that alcohol-based sanitisers have on skin lipids and fats that form part of the external skin structure and barrier.Due to their high pH, preservatives and colourants content, skin irritation and dermatitis were noted as a result of overzealous hand soap washing that was frequent and often times prolonged with no moisturisers used afterwards to repair the barrier properties of the skin.8Both bar and liquid hand soaps are commonly used as cleansers. They typically have an alkaline pH of 9–10, because of their prototypical anionic surfactant nature, their use can result in marked skin dryness and accompanied irritation. In a study, the general prevalence rate of occupational skin damages was 97.0% (526/542) among first-line healthcare workers with the hands being significantly affected.9The skin is the first line of defence and barrier against different types of infections. Its integrity can be lost due to various external factors, leading to loss of moisture, dryness and pruritus.10The protective nature of the skin allows for a physiological shield that protects against the entry of allergens, microbes, including viruses of different types. The same barrier helps in maintaining homeostasis, by preventing loss of body fluid and electrolytes. Compromise in the barrier can result in invasion of foreign bodies transcutaneously, introduction of toxins into the deeper skin structures as well as loss of fluids through interrupted skin integrity. Loss of fluids in turn leads to skin dryness and subsequent itching.Intensified handwashing and disinfection can cause irritant contact dermatitis by interrupting the epidermal barrier functions. As in other areas of occupational dermatology, the use of disinfectants alone is better tolerated than the combination of soap and disinfectant. Protective creams and other forms of emollients before the shift and moisturisers during the day reduce the risk of occupational hand dermatitis.Soap removes dirt and inactivates viruses by disrupting the lipid membrane and intracellular lipids. There is evidence to support soap as a more effective method of hand hygiene than hand sanitiser.11Latex glove usage by those combating the pandemic as front-line healthcare workers also resulted in increased incidence of hand dermatitis. This led to symptoms such as local itching and occasional pain. Clinical signs noted were swelling, diffuse erythema, pustulation, vesiculation, scaling and pigment changes both on the dorsal and palmar aspects of the hands .119Other clinical signs noted often are xerosis, eczematous lesions, and even maceration. Despite the increased frequency of handwashing and disinfection, a recently conducted survey revealed that only 22.1% used moisturisers regularly.Avoidance of identified triggers, depending on the ingredients in some soaps and sanitisers, not all result in skin reactions, even in sensitive skin type of individuals.The use of hand moisturisers after hand washing and regularly during the day is highly recommended.For sensitive skin, emollients that are hypo-allergic, preservative-free and oil in cream-based type of formulation is advised to reduce the risk of allergies.Soap subsets that are hypo-allergic will also result in lesser skin irritation, while removing unwanted microorganism and exfoliated (dead) corneum cells.Other soap subsets that are of unquestionable importance include glycerin and superfatted soaps. They contain humectants, which help significantly in retaining moisture after hand washing.Lukewarm water is advised over the use of hot water in hand washing. This prevents moisture loss as a result of skin dehydration.With any noticeable skin changes that are causing consternation or medical concern, a dermatologist must be consulted.Hand creams and other types of emollients: These are mostly over-the-counter products, highly effective in dry skin and restoring the skin barrier.Analgesics: In cases of pain or tenderness associated with the skin reaction, mostly with contact dermatitis.Oral or topical antihistamines: Can be prescribed when skin reactions are associated with marked itching for a specified duration based on clinical exam, the degree and extent of involvement.12Low to medium potency corticosteroids: In cases of dermatitis, steroids assist as anti-inflammatory agents through action on lymphocytes and other immune regulating cells.Oral corticosteroids: Highly effective in acute management of most forms of dermatitis.The use of alcohol-based sanitisers and regular hand washing remains key in good hygiene practice and reducing the spread of all forms of microbes. However, the dangers of sanitisers and frequent hand washing also need to be emphasised. Regular usage of emollients like hand creams remains key in reducing the unwanted drying effects of repeated hand washing and the potential allergies linked to strong sanitiser usage.


Hydrogel materials have been used extensively in microbial electrochemical technology (MET) and sensor development due to their high biocompatibility and low toxicity. With an increasing demand for sensors across different sectors, it is crucial to understand the current state within the sectors of hydrogel METs and sensors. Surprisingly, a systematic review examining the application of hydrogel-based METs to sensor technologies has not yet been conducted. This review aimed to identify the current research progress surrounding the incorporation of hydrogels within METs and sensors development, with a specific focus on microbial fuel cells (MFCs) and microbial electrolysis cells (MECs). The manufacturing process/cost, operational performance, analysis accuracy and stability of typical hydrogel materials in METs and sensors were summarised and analysed. The current challenges facing the technology as well as potential direction for future research were also discussed. This review will substantially promote the understanding of hydrogel materials used in METs and benefit the development of electrochemical biosensors using hydrogel-based METs. Microbial electrochemical technology (MET) is a fast-expanding field of research that utilises the metabolism of electrogenic microbes to catalyse oxidation and reduction reactions that occur in the anode and cathode ,2. The eMicrobial fuel cells (MFCs) and microbial electrolysis cells (MECs) are the most typical METs widely used for wastewater treatment and green energy production. In recent literature, they have garnered significant interest in the sensor industry due to their versatile biosensing properties and ability to use microorganisms as a biocatalyst . They haHydrogels have great advantages when applied to METs and sensor technology development. For instance, a typical biosensor consists of four parts: the analyte, the analyte binding substrate, the transducer, and the data processor shown in A 12]. T. T12]. TThe high versatility and unique properties of hydrogels have led to significant interest in hydrogel applications in MET and biosensors. Key terms search within the web of science databases shows that over 4700 studies have been conducted on hydrogel research within the sensors and biosensors sector . It has Here, we aim to give an overview of the applications of hydrogels within the sensor and MET sector, with a specific focus on MFC and MEC technology. The current literature on hydrogel applications in MFC-based sensors will be summarised and the limitations, barriers, and future trends will be discussed. This review will substantially promote the understanding of hydrogel materials used in METs and benefit the development of electrochemical biosensors using hydrogel-based METs.MFCs and MECs are two widely researched METs . AlthougA typical MFC contains an anodic and cathodic chamber separated by a proton exchange membrane (PEM) shown in MEC is a modified version of the MFC technology whereby the protons and electrons generated by the microbial biofilm are used to produce biofuel materials such as hydrogen gas and methane B 19]. U. U19]. UThe microbial community and microbe-electrode interaction play crucial roles in the efficiency of METs . CurrentIn the last ten years, hydrogels have become a common material used for microbial immobilisation, which is crucial for METs . The higE. coli is commonly used as the model organism in many studies due to its fast growth and easy manipulation. Other popular bacterial species used include S. oneidensis ,7257,72]Evaporation is a common limitation in many air cathodes, especially miniature MFCs, resulting in unstable power generation . HydrogeGeobacter sulfurreducens, in a graphene hydrogel. The graphene hydrogel electrode resulted in a three-time increase in current density in comparison to that of the bare graphene electrode. The SEM images of the hydrogel showed large pore structures with dense microbial growth on the electrodes.Hydrogels have also been used in MEC research for microbial immobilisation. Lescano et al. aimed to improve the efficiency of bioelectrochemical systems by improving the bacteria loading capacity of electrodes . GraphenGeobacter sulfurreducens bacteria were immobilised in an alginate and chitosan hydrogel and the current density, COD removal, and hydrogen production was measured. The MEC systems were treated with acetate and wastewater, one containing no additional bacteria and the other containing free-growing microbes. The study found that the non-immobilised system performed better when fed with acetate; however, this performance decreased significantly when the analytes were switched to wastewater. The opposite occurred for the hydrogel-immobilised MECs. Genetic analysis of the communities showed that the hydrogel was able to maintain the community composition of the exoelectrogens, and protect it from external competitors . T. T4+, NaAlthough the performance of the MEC was inferior to that of the MFC, it has the potential to be used for biosensing applications. MEC technology is currently still in its infancy. Further research to determine the optimal conditions and design configurations can resolve the limitations currently faced by the technology . Du et aTo date, several studies on the application of hydrogels to MFC sensors have been published. These identified examples are shown in The microbial biofilm plays a crucial role in the electricity production of MFCs. Previous research has aimed to enhance biofilm activity through genetic and microbial community engineering . In the Some authors have reported a potential sensor application of hydrogel MFCs. Winfield et al. produced a ceramic MFC to test the effect of oxygen on biofilm performance . The MFC+ modified bioanode reduced the start-up time by 50 h and >200 h for acetate and propionate respectively and increased the maximum cell voltage for all three VFAs. The agarose and polyacrylamide gels showed an increase in voltage; however, the PVA gel showed a decrease in voltage due to mass transport limitations. The polymer gels also only remained stable for 3–4 days due to the lack of mechanical and chemical stability between the electrode and gel matrix. Overall, the Ppy+-modified bioanode demonstrated stable and reproducible results over 2 weeks. Recovery times for the Ppy+ modified bioanode were also significantly faster than the control showing increased microbial resistance. Although the sensing range can be improved, the study demonstrates the potential use of hydrogels to enhance sensor performance.VFA concentrations are a good way of monitoring the performance of anaerobic and aerobic processors. An MFC-type biosensor was produced by Kuar et al. for the detection of the three most common types of VFAs, acetate, butyrate, and propionate . The stuMET is a fast-emerging sector that is increasingly being applied to the sensor industry. Its ability to bypass the use of an external transducer makes it highly popular for sensor applications. MFCs and MECs have both been developed for sensing applications due to their ability to detect a wide range of analytes. MFC has great potential for sensor applications, with many pieces of research demonstrating sustainable and long-term operations. Research on MEC-based sensors is limited in comparison to MFC research. Unlike MFCs, MECs are not autonomous and require energy input. This can affect the long-term stability and durability of MEC sensors. MEC-based sensor research is still novel. Further research on identification of the optimal conditions of MECs will be highly beneficial to advancing the field.Poor sensitivity, selectivity, detection rates, and detection limits are major limitations that are consistently commented on throughout both MFC- and MEC-based sensor research. Hydrogels have the potential to improve the sensitivity and selectivity of existing MFC sensors due to the range of unique properties they possess. The hydrogel industry is a fast-growing sector that has gained a significant amount of scientific interest in recent years. It has been extensively applied to various sensing platforms, exhibiting improved sensor performance.Hydrogel application to METs is gaining interest; however, publications are still limited. Within the MFC industry, research has almost exclusively focused on tuning hydrogel properties to improve the electricity output of MFC efficiency with a significant portion of the research focusing on anode hydrogels. The benefits of using hydrogels for MFC applications are clear, and it is expected that more research focusing on the effects of hydrogel composites on MFC performances will appear. Tailoring hydrogel composites for different MFC components should be further investigated. To date, most MET-based sensors are hand-made, with a time-consuming manufacturing process and low accuracy. Hydrogels have high tailorability and flexibility, which are ideal materials for automated manufacturing, such as 3D printing . EvidentAlthough the benefits of hydrogels application to METs and sensors are noted in the literature, research on hydrogel-based MET sensors is fractional. The lack of publications reflects the novelty of this sector of research, highlighting a potential research gap. The few existing studies on hydrogel-based MET sensors used MFC and simplistic, non-composite hydrogels were used. These studies, however, have unlocked a new, innovative area of research that could significantly advance and broaden the applications of sensor research.Future research should first focus on developing the use of MECs as sensing platforms, and concentration on optimising different materials and design configurations. A large variation of hydrogel composites exists, each with tailorable properties. The effect of these hydrogel composites on MET applications should also be explored. It is clear that METs show promising potential as sensing platforms. Future research should expand existing research by investigating the effect of hydrogel on the performance of MET-derived sensors. This could result in new developments within both the sensor and environmental technological fields.