The molybdenum disulfide (MoS₂, 98% purity), citric acid anhydrous (C₆H₈O₇, 99% purity), and ethanol (99.9% purity) were purchased from the Sisco Research Laboratories, India. Conductive film (polyethylene with carbon particles) was purchased from Thingbits (Mumbai, Maharashtra, India). The fabric substrate (nonwoven, 24 GSM) was supplied by Sivasamy Silks, India. The chemicals used in this experimental study were analytical grade and used without any purification. The entire experimental study utilized double-distilled water.

The crystalline arrangement of the MoS₂ coating on the nonwoven fabric was examined using XRD. The diffraction profile, as shown in Figure 3, confirms the effective deposition of crystallized MoS₂ on the nonwoven fabric. The diffractogram exhibits a sequence of clear and narrow peaks that are coherent with the hexagonal crystal phase of MoS₂ (JCPDS No. 37–1,492). The intense peak detected at 14.4° matches the (002) plane, which is the layered nature of MoS₂ and indicative of strong c-axis aligned and well-ordered crystal domains (Li et al., 2013). The obtained interlayer distance from the (002) peak is ∼0.62 nm, which is a key factor for pressure-sensing properties. This layered structure provides reversible compressibility with the applied mechanical force, thus inducing piezoresistive behavior, where inter-flake contact resistances change proportionally with pressure. This is translated into sensor sensitivity (Bai et al., 2022; Li et al., 2013). Particularly, the absence of significant background peaks from the nonwoven fabric suggests that the MoS₂ layer effectively dominates the diffraction signal. This signifies uniform, coherent MoS₂ coverage on the textile substrate, thereby leading to a well-connected conductive path all over the sensing area. This homogeneous distribution is crucial to obtain reproducible pressure responses with minimal signal variation and a stable baseline resistance for continuous pressure sensing (Sabarinathan et al., 2016; Ni et al., 2023). This supports the conclusion that the deposition process resulted in a relatively thick or well-oriented coating, effectively masking the substrate beneath.

The sharp (002) peak with high intensity indicates the good crystallinity and low structural defects of citric-acid-exfoliated MoS₂ layers, which is important to achieve a stable piezoresistive response during cyclic loading–unloading tests and rapid response–recovery time because of elastic behavior resulting from well-ordered layer structures (Aggarwal et al., 2024; Zhuo et al., 2023).

FTIR spectroscopy was used to study the functional groups and confirm the bonding mechanism relations between MoS₂ and the nonwoven fabric. The FTIR band of the MoS₂-treated fabric is shown in Figure 4; the wavenumber range extends from 4000 cm⁻¹ to 400 cm⁻¹. The broad absorption band appearing at approximately 3406 cm⁻¹ is the O–H stretching vibration of hydroxyl groups, and it originates from the natural hydrophilic property of nonwoven fabric. This peak is often seen in polymeric-based fabrics. The notable absorption band at 1647 cm⁻¹ matches the angular vibration of water molecules (H–O–H), verifying the residual water within the fabric matrix (Miller et al., 2025). The existence of these hydroxyl and water-related functional groups is advantageous for pressure sensing, as they contribute to the flexibility and compressibility of the fabric to allow it to undergo reversible deformation under applied pressure without compromising the structural integrity of the MoS₂ coating (Bhakhar et al., 2023; Deng et al., 2024; Pang et al., 2021). The bands at 1150 cm⁻¹ and 1,410 cm⁻¹ correspond to C–O and C–H vibrations from the fabric substrate. Notably, the bands noticed at lower energy region, particularly at 480 cm⁻¹ and 649 cm⁻¹, are attributed to the Mo–S linear vibrations, indicating the successful development and occurrence of MoS₂ on the fabric. The peak at 480 cm⁻¹ matches the A₁g and E¹ ₂g vibrational modes of MoS₂, which are distinctive indicators of the stacked configuration of MoS₂ (Late et al., 2012). The clear vibration mode of Mo–S provides evidence of the strong chemical bond between MoS₂ layers and the fabric, which is essential to maintain an electrical contact when compressing mechanically. This strong bonding prevents the sensor delamination during repeated pressure loading cycles and maintains the sensor performance as well as the device stability for extended time scales (Pang et al., 2021; Xu D. et al., 2022).

The presence of the Mo-S vibrational modes (480 cm⁻¹ and 649 cm⁻¹), in addition to the fabric-related features, also provides successful integration of MoS₂ without affecting the intrinsic flexibility of the substrate. Such chemical compatibility between MoS₂ and the fabric matrix is crucial for maintaining the mechanical properties required for sensing pressure, where the composite can be elastically deformed while maintaining electric connectivity through the MoS₂ percolation network that enables sensitive and repeatable response under applied pressure (Bhakhar et al., 2023; Wang et al., 2024; Hu et al., 2024; Chen et al., 2014; Zavala-Sanchez et al., 2022).

UV-Vis spectroscopy was used to characterize the optical behavior, and its absorption band is presented in Figure 5. The spectrum covers the range of 400–1,100 nm. It shows two significant absorption peaks at 615 nm and 680 nm, which are ascribed to the notable excitonic states of MoS₂. These spectral features are related to the A and B excitonic states, which originate from the spin–orbit separation of the valence band peak in the Brillouin zone K point (Mak et al., 2010). The excitonic peaks A (680 nm) and B (615 nm) with distinct separation (∼65 nm) are a clear indication of the successful exfoliation of MoS₂ into few-layer nanosheets using citric-acid-assisted liquid-phase exfoliation. Such a quantum-confined structure of few-layer MoS₂ is beneficial to the pressure-sensing application due to its larger surface-to-volume ratio and greater flexibility when compared with its bulk counterpart, leading to a better match onto fabric substrate and more significant mechanical sensitivity to applied pressure (Hashemi et al., 2022; Deng et al., 2024). The adherence of distinct A and B excitonic absorption peaks indicates the MoS₂ coating holds its layered formation and shows confinement-induced quantum effects that are stable with nanosheet formation. The preservation of excitonic characteristics even after being coated on the fabric substrate reveals that the semiconducting nature of MoS₂ nanosheets is preserved, which is essential for piezoresistive sensing processes. Intact electronic structure leads to the persistent modulation of charge transport by mechanical deformation, which plays a direct role in enabling the sensor to transduce pressure into measurable electrical signals (Bai et al., 2022; Safamariyam et al., 2025).

Moreover, the gradual decline in absorption ahead of 700 nm confirms the semiconducting behavior of MoS₂ and the occurrence of a tail in the near-infrared region, which is possibly caused by scattering effects from the nonwoven fabric (Chhowalla et al., 2013). The well-resolved excitonic absorption peaks, along with the semiconducting character of the absorption edge, validate that the citric acid exfoliation method can successfully produce optically and electronically active MoS₂ nanosheets. Consequently, this electronic characteristic is critical to obtain stable baseline conductivity and reproducible resistance changes under cyclic pressure loading, which guarantees a reliable sensor performance with a minimal signal drift in practical use (Bhakhar et al., 2023; Xu D. et al., 2022).

This technique is used for studying the molecular vibration and determining layer thickness in 2D materials. The Raman spectra (range: 100 cm⁻¹ to 1,000 cm⁻¹) are shown in Figure 6. Two distinct peaks are noted at 376 cm⁻¹ and 404 cm⁻¹, related to the E¹ ₂g and A₁g vibrational modes of MoS₂. The A₁g (404 cm⁻¹) mode was associated with the out-of-plane vibration of S atoms (Lee et al., 2010). The frequency difference (Δω) of 28 cm⁻¹ is observed between these modes, which is a key constraint used to identify the number of MoS₂ layers. This Δω of the 28 cm⁻¹ value demonstrates that the citric-acid-assisted exfoliation successfully produced few-layer MoS₂ (three to five layers) rather than bulk materials, which is preferable for pressure sensing. Few-layer structures provide an optimal thickness between a few layers for mechanical flexibility and electrical conductivity (thinner than the substrate deformation, but sufficiently thick to support stable charge-transport paths), promising better piezoresistive sensitivity than monolayer or bulk MoS₂ (Ni et al., 2023; Late et al., 2013). This layer thickness is consistent with the excitonic absorption peaks observed in UV-Vis spectroscopy and the interlayer spacing measured from XRD data, which validates the citric acid liquid-phase exfoliation method. The controllable number of layers is also important for the performance of sensors, because it directly affects the band structure, charge carrier mobility, and mechanical compliance, all critical parameters for achieving high sensitivity and stability response in flexible pressure sensors (Bai et al., 2022; Rawat et al., 2023).

The fine, sharp Raman peaks with small full-width at half-maximum reveal that MoS₂ nanosheets exhibit high crystalline quality after citric acid exfoliation and deposition on the fabric substrate. This retained crystallinity is crucial for the uniform electronic properties under mechanical deformation, which leads to repeatable and reproducible responses from the sensors after multiple pressure loading–unloading cycles without compromising the sensor performance (Bhakhar et al., 2023; Deng et al., 2024).

Scanning electron microscopy (SEM) and EDX analyses were used to characterize the surface morphology and map the elemental composition. Figure 7 displays the SEM images of (a) the nonwoven fabric and (b) the MoS₂-coated nonwoven fabric, while (c) shows the equivalent EDX spectrum. The nonwoven fabric in Figure 7a displays clean, smooth fibers with an even thickness and unstructured features. In contrast, the MoS₂-coated fabric sample in Figure 7b indicates a compact arrangement of granular and flaky particles on the fiber surface. The observed surface roughness indicates the successful deposition of MoS₂ nanosheets on the fiber arrangement. This conformal coating of MoS₂ nanosheets on individual fibers is essential for the pressure-sensing functionality, which enables a continuous conductive pathway in the 3D fabric structure. Due to the uniform distribution, mechanical compression at any region of the fabric results in predictable changes in inter-flake contact resistance and provides a consistent piezoresistive response across the entire sensor area (Bhakhar et al., 2023; Pang et al., 2021). The EDX spectrum in Figure 7c validates the presence of the essential elements Mo and S, which are the key elements of MoS₂. The stoichiometry of Mo:S is achieved in the EDX spectrum, suggesting that the chemical composition of the MoS₂ was maintained during citric-acid-assisted exfoliation and deposition without being oxidized or decomposed. This structural integrity is crucial to retain the semiconductor behavior that is necessary for stable electrical conduction and for reliable piezoresistive sensor performance (Bai et al., 2022; Deng et al., 2024). This is evidence of the selective and efficient incorporation of MoS₂ on the nonwoven fabric surface.

The SEM morphological analysis and EDX elemental confirmation validate the successful MoS₂ nanosheet deposition on flexible fabric substrate using citric-acid-assisted liquid-phase exfoliation. The resulting surface roughness and particle distribution are advantageous for pressure sensing, as these features can increase the effective contact area between MoS₂ layers in a compressed condition and provide an enhanced piezoresistive effect to prepare sensitive sensors. These morphological characteristics, along with the preserved stoichiometry of MoS₂, enable a stable baseline resistance and reproducible response under applied pressure (Xu D. et al., 2022; Hu et al., 2024).

AFM images (Figure 8) are 50 μm × 50 µm scans using a resolution of 512 × 512 pixels performed in static force mode using a ContAI-G cantilever at room temperature with corresponding height maps, scale bars (x/y:50 µm), color legends (z:0–613 nm), and z-axis references; representative of multiple regions. It is important to note that AFM-measured height values reflect the topographic surface relief of the coated fabric, including contributions from stacked nanosheet aggregates and substrate roughness, rather than the thickness of individual MoS₂ nanosheets, which are characterized as few-layered structures (three to five layers) as confirmed by Raman spectroscopy. The surface height deviation ranges from 0 to 2.56 µm (line fit: 2.45 µm), which resulted in an average mean height of 310.23 nm, RMS roughness of 399.52 nm, peak height of 1,388.7 nm, and valley depth of −1,280.7 nm. These values indicate a flaky, textured property characteristic of the nanosheet composite. The observed surface height variations of 2–3 µm from AFM measurements represent topographic relief arising from stacked MoS₂ nanosheet aggregates on the fabric surface, rather than the thickness of individual nanosheets. These aggregated structures, combined with high RMS roughness (399.52 nm), improve piezoresistive gauge factors by facilitating strain-induced nanosheet sliding at their junctions and network reconstruction, respectively, with larger aggregate formations inducing greater resistance changes at contact points. This is consistent with our Raman analysis, which indicates few-layer nanosheets. For analogous graphene networks, thicker nanosheets (e.g., 3–20 nm) would linearly enhance the resistivity and gauge factors through enhanced inter-flake contributions, which mirrors the mechanisms in MoS₂-based composites. This AFM-based roughness is responsible for increasing sensitivity during mechanical loading, as it is directly related to the electrical piezoresistive characteristics. The data also show no scanning artifacts, consistent with viable surface analysis (Zeng et al., 2011).

Control experiments conducted with a four-probe measurement method at a constant current of 1.0000 mA distinctly differentiate the role of green synthesis in the electrical response of nonwoven fabric substrates. The uncoated nonwoven fabric reveals very high resistance of 7.3 × 10⁹ Ω and sheet resistance of ∼2.5 × 10¹⁰ Ω/sq, which confirms its intrinsically insulating character with no continuous charge-transport pathways. After coating with MoS₂ without citric acid, the resistance decreases noticeably to 1.2259 × 10³ Ω, and the sheet resistance is 5.5532 × 10³ Ω/sq, which implies partial conductive paths induced by aggregated MoS₂ domains on the fiber surface. However, the lower sheet resistance is due to conductive islands that are localized and not a uniform percolation across the nonwoven substrate. In contrast, the citric-acid-assisted MoS₂-coated fabric displayed a resistance of 2.6448 × 10³ Ω and a corresponding sheet resistance of 11.98 × 10³ Ω/sq, determined from a stable voltage response (2.6448 V at 1 mA, with 8.9364 mV across the inner probes) that was maintained over 5.41 s. The temporal stability of these electrical parameters confirms consistent probe fabric contact and the intrinsic uniformity of the coating. Although the citric-acid-assisted MoS₂ coating shows higher sheet resistance than the untreated version, this arises from a fundamental change in conduction mechanism from localized cluster pathways to a uniform nanosheet percolation network. Citric acid serves as a complexing agent that promotes precise exfoliation into nanoscale flakes, inhibiting restacking while favoring well-ordered flake alignment and effective inter-flake electrical contacts (Bai et al., 2022). This nanoscale organization enables consistent modulation of junction and tunneling resistance under mechanical strain, which is essential for effective piezoresistive sensing. In comparison, the irregular stacking of larger (1–5 µm) MoS₂ aggregates formed without citric acid creates irregular junctions and limited resistance variation under deformation. These findings collectively demonstrate that citric-acid-assisted synthesis improves both static electrical uniformity and dynamic piezoresistive response, both of which are essential for reliable wearable sensor performance (Eda et al., 2011; Choi et al., 2017; Radisavljevic et al., 2011; Liu et al., 2016a).

The electric response of the material was studied by measuring voltage and resistance (Figure 9) using a weight range from 50 g to 500 g. All experiments were carried out on three independently prepared samples (n = 3), and data are presented as mean ± standard deviation (SD). The output response is shown as two plots: Figure 9a shows weight vs. voltage, and Figure 9b shows weight vs. resistance. Both the measurements exhibit good reproducibility with the coefficient of variation (CV) < 2%. In the voltage response, the voltage increases linearly as the applied weight increases. At 50 g, the voltage recorded is 2.85 ± 0.03 V. While increasing the weight gradually, the voltage response also increases to 3.63 ± 0.04 V at 100 g, to 4.22 ± 0.03 V at 150 g, and to approximately 4.73 ± 0.04 V at 250 g. For 300 g–500 g, the voltage response increases gradually and stabilizes at 4.99 ± 0.01 V. The small error bar in Figure 9a indicates the measurement precision is excellent (CV < 1.05%). This response signifies a nonlinear and positive correlation between weight and voltage, with a sharp transition at the initial weight followed by a slower increase. The conductivity of the material is improved due to the enriched charge transport, which is clearly shown in the plot. The resistance curve exhibits an apparent downward tendency as the loading weights increase. Resistance is high, 7.52 ± 0.11 kΩ, at 50 g. As the load increases to 100 g, the resistance decreased rapidly to approximately 3.79 ± 0.07 kΩ and subsequently to 1.87 ± 0.03 kΩ at 150 g, after which the resistance change becomes relatively smaller. At 200 g, the resistance decreases to approximately 1.02 ± 0.02 kΩ and further decreases to 0.30 ± 0.001 kΩ at 300 g; and subsequently becomes relatively constant with a resistance of approximately 0.014 (14 Ω) at higher weights (400 g–500 g). Very good reproducibility was maintained between the estimates (CV = 0.00–1.73%). This would indicate that resistance has a nonlinear inverse relationship with weight, such that an increase in weight significantly decreases resistance, but further increases yield a reduced change, signifying a saturation regime. The decrease in resistance may be due to heavier compression that reduces voids between conducting sites, thus providing better electrical contact. Resistance and voltage have inverse trends observed using both measurements: higher voltage, less resistance. Such response behavior indicates mechanical input with consistent electrical output. Because of the gentle curve and lack of sharp peaks, the measurements seem stable and reliable (Late et al., 2013). Such small error bars in Figures 9a,b reveal its excellent inter-sample reproducibility (CV less than 2%), indicating consistent sensor fabrication. This shift from fast approach to saturation in the two curves is evidence of an anticipated and regulated response to higher mechanical stimulation. The data show that both electrical parameters vary in a consistent nonlinear fashion as load is applied, with good reproducibility, making the material promising for use in quantitative sensing (Trung and Lee, 2016; Lian et al., 2020; Gu et al., 2024).

The electric response of a sample was investigated at applied pressures (Figure 10) ranging from 600 Pa to 6,000 Pa. Measurements were taken at both (Figure 10a) pressure versus resistance and (Figure 10b) pressure versus voltage. The resistance values exhibit a distinct inverse correlation with pressure. At the lowest pressure (600 Pa), the resistance is at the maximum value of 7.52 ± 0.06 kΩ. A sharp decline in resistance to 3.79 ± 0.04 kΩ is observed at 1,000 Pa. This tendency also extends into the higher pressure range up to 2000 Pa, where the resistance levels off to 1.87 ± 0.01 kΩ. Above this, the decrease becomes less steep. Resistance at 3,000 Pa decreases to 0.56 ± 0.00 kΩ, drops to 0.048 ± 0.001 kΩ at 5,489 Pa, and further decreases to 0.014 ± 0.001 kΩ (14 Ω) at 6,099 Pa. The small error bars visible in Figure 10a confirm excellent measurement precision (CV < 2% across all conditions). This trend indicates that, in the lower-pressure regime, the sample is pressure-sensitive, while, in the higher pressure regime, a saturation effect has occurred, and when an additional pressure is applied, less change in resistance is observed. The rapid decrease followed by the gradual curve suggests that the conductive paths are formed and stabilized at higher compressive strain.

The pressure–voltage relationship follows the exact opposite trend. Voltage increases with applied pressure, beginning with 2.85 ± 0.02 V at 600 Pa. The voltage follows the pressure: as the pressure goes from 600 to 1,000 Pa, the voltage increases from 2.85 to 3.62 ± 0.02 V, respectively; at 2000 Pa, the voltage reaches 4.22 ± 0.02 V. It continues to increase, but at a slower pace. At 3,000 Pa, a voltage of 4.74 ± 0.03 V is required; the voltage gradually increases to 4.99 ± 0.01 at 6,000 Pa. Error bars in Figure 10b demonstrate excellent reproducibility (CV < 1.05%). This suggests the voltage is more sensitive to the initial pressure increase and then gradually saturates, following the resistance behavior in the opposite direction. The increase is linear and constant, indicating a stable electrical response throughout the measured range (Yang et al., 2019; Wang et al., 2017).

Both graphs confirm a stable and reversible electrical signal under external pressure. The small error bars in both plots also confirm the inter-sample consistency (CV < 2%), which indicates a reliable sensor fabrication. The current decreases as the voltage increases in a nonlinear but continuous way. Such negative resistance with respect to voltage is found in conductive materials for which the electrical conductivity is dependent upon mechanical deformation. Results show that the electrical characteristics can be directly modulated by pressure, with high repeatability (n = 3, CV < 2%), which provides good application potential in quantitative bio-pressure detection, particularly in the sensitive low-pressure range (600–2,400 Pa) (Alhashmi Alamer et al., 2022).

The voltage value was recorded by five repeated tests on the single sample at the same test conditions (250 g) to verify the repeatability and stability (Figure 11). The voltage is nearly the same for all five cycles, as shown in the bar chart. The measured voltages were 4.73 V, 4.72 V, 4.70 V, 4.71 V, and 4.73 V for iterations one to five, respectively, with a mean of 4.72 ± 0.01 V (mean ± SD, n = 5). The CV was calculated to be 0.57%, indicating excellent repeatability (CV < 1%). The highly reproducible voltage response (CV = 0.57%, n = 5) exhibits uniform electrical properties across sequential measurements that only show a deviation of ±0.03 V from the mean value. This low variance corresponds to minimal hysteresis and stable contact resistance in the MoS₂ nonwoven fabric network. This response is used to validate the reliability of electrical characteristics under cyclic loading. The data show that the voltage output is highly reproducible across repeated measurements (n = 5, CV = 0.57%) and the behavior of the sensor is consistent under identical loading conditions. The minimal variation observed between cycles further confirms the absence of significant drift, hysteresis, or degradation over short-term cycling. This excellent repeatability (CV < 1%), when combined with the previously established inter-sample reproducibility (n = 3, CV < 2%), confirms reliability for our MoS₂-textile sensor in quantitative sensing applications (Yang et al., 2019; Wang et al., 2017).

The long-term stability was tested by recording the output voltage of a single sample at a constant load (300 g) for 300 s (Figure 12). Such continuous monitoring is routinely used to monitor signal drift and sensor temporal stability. The plot demonstrates a very stable voltage output of approximately 4.7 V drawn over the entire period. The voltage was constant at 4.73 ± 0.03 V (mean ± SD of 300 s), with the maximum drift (∼±0.6%) over a 5-min measurement window. Slight undulations can be seen in the waveform; however, these undulations are extremely minimal and well within tolerable limits, suggesting that no appreciable drift is present. The signal is stable at the test start and stop points, and there are no sharp increases, sharp decreases, or irregular trends. The fluctuations of the waveform are minimal (<±0.03 V) and well within the acceptable level, due to inherent noise in the measurement rather than instability of the signal itself. The lack of progressive drift, sharp transients, or irregular trends offers good temporal stability with no evidence of electrical degradation over the period measured. The continuous monitoring shows good temporal stability (drift <1% over 300 s), which reveals that the sensor can provide a constant electrical output under sustained static loading. Together with the good repeatability (CV = 0.57%, n = 5) and inter-sample reproducibility (CV < 2%, n = 3), these results confirm the reliability of the MoS₂-textile sensor for short-time cycles as well as static measurements over the long term.

To evaluate the practical durability of the sensor, its washing resistance was tested according to the AATCC 135 standard (Figure 13). Three independently fabricated samples (n = 3) underwent seven washing cycles, and the resistance was measured after each cycle (results expressed as mean ± SD, CV < 1.6%). The initial resistance of 6.92 ± 0.06 kΩ became 19.32 ± 0.07 kΩ after the seventh cycle, corresponding to a 2.8-fold increase, with a notable acceleration in degradation beyond the fourth cycle. The observed increase in resistance with washing cycles is consistent with several potential degradation mechanisms. Based on the electrical behavior and the nature of the washing process, the resistance increase can be attributed to: (i) partial detachment of MoS₂ nanosheets from fiber surfaces due to mechanical agitation and surfactant action, (ii) progressive weakening of the MoS₂–fiber interfacial bonding through repeated wetting and drying cycles, (iii) possible restacking of the nanosheets, reducing the number of conductive pathways, and (iv) microstructural deformation of the textile substrate disrupting the percolation network. While these mechanisms are inferred from the systematic electrical measurements, they are consistent with the established understanding of nanomaterial–textile interactions under washing conditions (Mitrano et al., 2016; Beigzadeh et al., 2024; Syduzzaman et al., 2023). The nonlinear resistance change (∼30% versus 83%) during the cycles 0–3 compared to that of the cycles of 4–7 clearly indicates a transition from minor surface degradation to significant conductive network disruption once a critical damage threshold is reached. Despite the nearly threefold increase in resistance, the sensor remained functioning across all washing cycles, signifying that the remaining network connectivity was sufficient to preserve electrical continuity. The steady and progressive resistance change, along with good reproducibility (CV < 1.6%), mirrors a smooth and predictable degradation pattern, allowing recalibration-based changes for consistent performance in real-world use. The washing durability observed over seven operational cycles is considered satisfactory for short-term or semi-disposable wearable applications (Alhashmi Alamer et al., 2022).

The temperature-dependent electrical performance of the sensor was determined by measuring resistance in the 30 °C–100 °C range (Figure 14). The sensor displayed negative temperature coefficient (NTC) behavior, with resistance decreasing from 6.52 ± 0.16 kΩ at 30 °C to 4.90 ± 0.07 kΩ at 40 °C, 3.68 ± 0.05 kΩ at 50 °C, 2.05 ± 0.03 kΩ at 70 °C, and 0.81 ± 0.02 kΩ at 100 °C, corresponding to an eightfold reduction in resistance with excellent reproducibility (CV = 1.27–2.41%). The NTC response can be explained on the basis of thermally activated charge carriers transport, in which higher temperatures enhance the electron hopping between MoS₂ nanosheets, thereby lowering the interfacial contact resistance and enhancing carrier mobility. The nonlinear resistance reduction, pronounced at low temperatures, indicates that the thermally activated conduction governs in the initial range and tends to reach the intrinsic limit of conductivity of the material with increasing temperature. Note that the response curve is smooth and continuous without discontinuities, indicating a stable and reversible thermal behavior. This stable response, even at NTC behavior, maintains the stable thermal performance of the sensor in a wearable scenario. High reproducibility also indicates its potential for temperature-compensated pressure sensing or dual-mode temperature–pressure application (Gu et al., 2024; Han et al., 2024; Liu et al., 2016b).

The weight-dependent voltage output revealed a sigmoidal pattern (Figure 15), characterized by a rapid initial increase from 2.85 ± 0.03 V at 50 g to 4.22 ± 0.03 V at 150 g, followed by gradual saturation toward 4.99 ± 0.01 V at 500 g. The behavior was well modeled by a four-parameter logistic, with R² (0.9999) and statistical fitting parameters significance of p (9.90 × 10⁻⁹). The inflection point (EC₅₀ = 112 g) marks the transition from the high-sensitivity region to the gradual saturation regime. The observed logistic behavior is consistent with percolation theory. At lower loads (50–150 g), pressure application triggers a fast formation of conductive networks by bringing two MoS₂ nanosheets closer, which effectively decreases interparticle gaps and contact resistance. Each incremental weight leads to new conductive junctions within an initially disconnected network, which has a high sensitivity for the response. The intermediate region (∼100–200 g) corresponds to the percolation threshold, where a continuous conductive network becomes fully established across the sensing structure. Above this threshold (>200 g), further compression results in diminishing gains, as the conductive network is already well-established. Additional pressure only causes minor flake rearrangement along with a slight increase in area of contact, rather than forming new conduction paths. This physical saturation is caused by an asymptotic approach to the potential at maximum voltage output (∼5 V) determined intrinsically by the electronic property of MoS₂ and its packing density. Therefore, the sigmoidal response becomes a natural result of the percolation dynamics with rapid conductivity increase near the percolation threshold, followed by reduced sensitivity once optimal network connectivity is achieved (Trung and Lee, 2016; Gong et al., 2015).

The pressure-dependent resistance exhibited an exponential decay trend, with resistance dropping rapidly from 7.52 ± 0.06 kΩ at 600 Pa to 1.87 ± 0.01 kΩ at 1800 Pa and then gradually approaching 0.014 ± 0.001 kΩ at 6,000 Pa (Figure 16). This response was well fitted by an exponential decay function (R² = 0.9998), yielding a decay constant t₁ = 882, which corresponds to a reduction of the resistance to approximately 37% of its initial value at this characteristic pressure, consistent with percolation-based piezoresistive models for composites. The exponential decay behavior can be interpreted in terms of pressure-driven evolution of contact resistance and percolation pathways within the MoS₂ network. At low pressures (600–1800 Pa), compression substantially narrows the gaps between adjacent MoS₂ nanosheets, leading to a steep increase in the number of conductive contacts and in the tunneling probability, in line with quantum tunneling theory, where current depends exponentially on barrier width. Concurrently, the applied pressure increases the effective contact area at MoS₂ and fiber interfaces and reduces interfacial voids, thereby decreasing contact resistance, in agreement with contact mechanics descriptions of pressure area relationships. Beyond approximately 2,000 Pa, the conductive network approaches a highly connected state in which most effective contact sites are already engaged, and further compression only produces marginal gains in connectivity. In this regime, the overall resistance becomes increasingly governed by the intrinsic resistance of the MoS₂ sheets and their saturated packing configuration rather than by further reductions in interparticle gaps, yielding a saturation-like plateau. The exponential form therefore provides a compact mathematical representation of the transition from a contact-resistance-dominated regime, where resistance is extremely sensitive to gap reduction, to an intrinsic-resistance-dominated regime, in accordance with percolation theory for pressure-sensitive composite systems (Trung and Lee, 2016).

Mechanical memory and hysteresis were characterized by recording voltage responses during loading–unloading cycles from 50–500 g (Figure 17), with consistent results across three samples (CV < 1.1%). The maximal hysteresis was 0.11 V at 250 g (loading: 4.73 ± 0.04 V; unloading: 4.62 ± 0.03 V), and the average hysteresis over all loading conditions was 0.07 V, which is less than 1%–2% of the signal range. The consistently low hysteresis reflects limited energy dissipation during compression–decompression, stemming from the textile substrate’s elastic recovery and reversible rearrangement of the MoS₂ nanosheet without permanent deformation. This performance (1%–2% hysteresis) is competitive with typical textile piezoresistive sensors: graphene-coated fabric (3%–8%), CNT embedded textiles (5%–15%), conducting polymers (10%–25%), and metal nanowires (2%–5%). These characteristics result from strong van der Waals forces that allow for reversible nanosheet stacking in the sensor, high mechanical strength of the MoS₂, and low viscoelastic losses due to minimal polymer binder and the textile’s inherent mechanical properties. Combined with a good cycle repeatability (CV = 0.57% after five cycles) and inter-sample uniformity (CV < 2%), all these features demonstrate their excellent mechanical reliability compared to conventional textile sensors. The minimal hysteresis enables the reliable dynamic pressure sensing for applications including gait analysis, human–machine interfaces, and continuous health monitoring, because they would compromise the accuracy due to lag effects (Wang et al., 2017; Gu et al., 2024; Xue et al., 2024; Liu et al., 2021; Ryan et al., 2017).

Antibacterial activity was determined using the AATCC 147 Parallel Streak Method against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus (Figure 18 (a and b)). Two separately prepared MoS₂ textile samples (S1 and S2) were tested by the AATCC 147 method. As it is a qualitative rather than statistical replication, it gives visual evidence of antibacterial activity in terms of ZOI. Samples showed well-defined inhibition zones against E. coli (S1: 28 mm, and S2: 25 mm), while larger zones were reported for S. aureus (S1: 30 mm and S2: 28 mm), with untreated controls presenting no inhibition, confirming that the activity originates from MoS₂. Key antibacterial mechanisms are as follows: (1) physical destruction of cell membranes due to the sharp-edged MoS₂ nanosheets penetrating through bacterial cell walls, (2) reactive oxygen species generation leading to oxidative stress and DNA/protein damage, (3) phospholipid extraction from bacterial membranes by van der Waals interactions, and (4) released Mo ions interfering with metabolic enzymes. The higher efficiency against Gram-positive S. aureus (28–30 mm) than Gram-negative E. coli (25–28 mm) is attributed to the single layer of peptidoglycan in Gram-positive species, which is thinner, weaker, and penetrable, compared with the double membrane barrier of Gram-negative species. AATCC 147 is a qualitative screening method that provides a visual indication (zone presence/absence) rather than quantitative reduction rates, and thus does not require statistical significance testing. This antibacterial activity is important for wearable sensors that must stay on the skin for extended periods of time, as bacterial colonization leads to irritation and sensor degradation. Combined efficacy against both S. aureus (skin commensal) and E. coli (contamination indicator) confirms potential for healthcare monitoring, wound dressings, and athletic clothing. Together with biocompatibility (cell viability >70%, ISO 10993), the sensor demonstrates the combination of antimicrobial protection and mammalian cell compatibility essential for safe long-term wearable applications (Gu et al., 2024; Mu et al., 2023; Naskar et al., 2022).

Cytotoxicity was evaluated using L929 fibroblast cells (National Centre for Cell Science, Pune, India) according to ISO 10993–5 guidelines (Figure 19). Cells were exposed to MoS₂ extract concentrations ranging from 0–100 μg/mL for 24 h, with viability measured in triplicate (n = 3, MTT assay, CV < 1.25%). Cell viability showed dose-dependent reduction: 100.00% ± 0.00% (0 μg/mL control), 95.23% ± 1.18% (20 μg/mL), 89.80% ± 1.04% (40 μg/mL), 87.57% ± 1.03% (60 μg/mL), 83.07% ± 0.76% (80 μg/mL), and 79.97% ± 0.95% (100 μg/mL), maintaining >70% viability across all concentrations per the ISO 10993–5 non-cytotoxic threshold. The mechanisms of observed cytotoxicity are minimal toxicity (∼10%–15% cell reduction) for low concentrations (20–60 μg/mL), as cellular antioxidant systems neutralize reactive oxygen species (ROS) produced by MoS₂, and moderate (∼17%–20%) for higher concentrations (80–100 μg/mL). As a result of enhanced endocytosis, increased levels of intracellular ROS overwhelm the antioxidant capacity, causing mild membrane disruption and inflammatory responses. The essential difference between strong antibacterial activity and low mammalian cytotoxicity is connected with the structural difference; the rigid peptidoglycan walls of bacteria are highly prone to physical penetration or ROS, whereas the flexible phospholipid membranes of mammalian cells have mechanical strength protection. In addition, mammalian cells hold sophisticated antioxidant/repair systems that are absent in bacteria. Surface morphology plays a key role in cytotoxicity: the layered MoS₂ nanosheets with sub-micron lateral dimensions and nanoscale thickness immobilized on the textile substrate limit direct cell–nanosheet contact. Extracted material likely contains smaller, oxidized flake fragments with reduced toxicity. The gradual viability declines without sharp threshold points to concentration-dependent chemical ROS interactions rather than acute physical damage. As Per ISO 10993–5 (viability >70% = non-cytotoxic), the sensor is biocompatible across all tested concentrations (lowest: 79.97%, above threshold), and this biocompatibility, in addition to antibacterial capacity, affords key dual functionality: active bactericidal action (preventing infection/biofouling) while maintaining mammalian cell compatibility (preventing skin irritation/inflammation). This selective antimicrobial-biocompatible profile is crucial for wearable healthcare sensors requiring extended skin contact, wound monitoring systems, and implantable pressure sensors, where both infection prevention and tissue compatibility are essential (Er et al., 2019).

Table 1 shows a comprehensive comparison of our MoS₂-textile sensor with state-of-the-art textile-based piezoresistive sensors using AgNW, chitosan/MXene, graphene, CNT/2D materials, and PEDOT:PSS systems (Zhang et al., 2024; Lian et al., 2020; Gu et al., 2024; Yang et al., 2021; Wang Y. et al., 2025; Wibowo et al., 2024). Our sensor shows competitive sensitivity (<2 kPa⁻¹ in the 0.6–6.1 kPa range), comparable to graphene-coated textiles (2.12–6.98 kPa⁻¹) and superior to AgNW/fabric (0.66 kPa⁻¹) and PEDOT:PSS/SWCNT (0.034 kPa⁻¹). The most captivating advantage lies in its excellent reproducibility: cycle repeatability CV of 0.57% (n = 5) and inter-sample CV <2% (n = 3), outperforming the other textile sensors. Hysteresis remains among the lowest at 1%–2%, significantly better than chitosan/MXene (5.8%), AgNW (∼5%), graphene (3%–8%), PEDOT:PSS films (10%–15%), and conductive fabric/PU (∼8%), representing greater mechanical stability (Yang et al., 2021; Wang Y. et al., 2025; Wibowo et al., 2024). Comprehensive temperature characterization (30 °C–100 °C, negative temperature coefficient (NTC) behavior) reveals a systematic electrical response rarely documented in textile sensor literature. The sensor’s most distinctive advantage is its exceptional reproducibility, with a cycle repeatability CV of 0.57% (n = 5) and an inter-sample CV <2% (n = 3), outperforming the reported textile sensors. Temperature-dependent electrical characterization (30 °C–100 °C, NTC behavior) provides systematic response data rarely documented for textile sensors (Cheng et al., 2021; Khan and Umer, 2024). The proven viability (79.97% for ISO 10993–5), in conjunction with an antibacterial effect on Escherichia coli and Staphylococcus aureus, is a dual functionality that is only found within chitosan/MXene systems. AgNW, graphene, CNT, and PEDOT:PSS sensors typically lack both properties. Wash durability up to seven functional cycles (AATCC 135) shows predictable resistance development that validates the practical, real-world applicability. The MoS2-textile sensor offers a unique combination of <1% reproducibility, low 1%–2% hysteresis, dual biocompatibility/antibacterial properties, and detailed multi-parameter data, such as temperature response, and is therefore exceptionally well-suited for healthcare wearables in prolonged contact with the skin.