IEEE Sensors Letters最新文献

{"title":"Soft, Scalable Spacer-Knitted Piezoresistive Pressure Sensors With Tunable Localized Sensitivity Enabled by Heat-Expandable Yarn Inlays","authors":"Aftab Ahmed;Rahul Bhaumik;Rachele Didero;Michael Haller","doi":"10.1109/LSENS.2026.3699462","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3699462","url":null,"abstract":"Soft textile pressure sensors provide superior comfort for wearable systems but often suffer from limited compressibility, tunability, and complex postprocessing. A fully textile-based spacer-knitted piezoresistive pressure sensor is fabricated in a single step using a standard V-bed flat knitting machine with heat-expandable yarn inlays. The expandable inlays form highly compliant spacer regions, yielding effective compressive moduli of 54 and <inline-formula><tex-math>$77 ,mathrm{ kPa}$</tex-math></inline-formula> for the two- and four-inlay configurations. Sensor sensitivity is tunable through sensor size and internal architecture, ranging from <inline-formula><tex-math>$-1.067$</tex-math></inline-formula> to <inline-formula><tex-math>$-0.251,mathrm{% ; kPa^{-1}}$</tex-math></inline-formula> for sensor sizes between 2.5 and <inline-formula><tex-math>$7.5 ,text{cm}$</tex-math></inline-formula> and from <inline-formula><tex-math>$-0.678$</tex-math></inline-formula> to <inline-formula><tex-math>$-0.180,mathrm{% ; kPa^{-1}}$</tex-math></inline-formula> by varying spacer inlays and resistive yarn plies, while maintaining linear responses up to <inline-formula><tex-math>$60 ,text{kPa}$</tex-math></inline-formula>. Stable operation over <inline-formula><tex-math>$10{ }000$</tex-math></inline-formula> loading cycles and preserved electrical integrity after ten washing cycles confirm suitability for long-term wearable and nonwearable pressure sensing applications. The real-world applicability of the proposed spacer-knitted pressure-sensitive structures is further demonstrated by a knee cuff and a 2 × 2 sensor matrix.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"2503104-2503107"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148506306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpretable Sensor Channel Attribution for Wearable Activity Recognition via xLSTM-Backed Decision Trees","authors":"Lei Zhang;Ying Zhang","doi":"10.1109/LSENS.2026.3702086","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3702086","url":null,"abstract":"Wearable sensor-based human activity recognition is critical for healthcare monitoring, yet the inherent opacity limits the diagnosis of sensor signal contributions. To address this, we propose a hybrid framework comprising an extended long short-term memory-backed decision tree and a temporal-feature bivariate integrated gradients module. Unlike traditional methods that aggregate data over time, this approach decomposes decision contributions into specific temporal phases and sensor axes for granular traceability. Crucially, we validate the interpretability through a dual protocol. The occlusion analysis confirms that masking identified signal features explicitly weakens decision certainty, while parameter randomization tests prove that the attribution logic relies on learned signal dynamics rather than statistical artifacts. Furthermore, evaluations on the human activity and postural transitionsand opportunity datasets yield competitive accuracies of 92.18% and 89.91%, respectively. These results validate the framework as a diagnostic tool that could inform future energy-efficient hardware design.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"7003504-7003504"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148442787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemiluminescence Portable Device Integrated With Microfluidic Chip for Free Chlorine Detection in Tap Water","authors":"Kavita P. Manekar;Meghana A. Hasamnis;Pravin Manekar","doi":"10.1109/LSENS.2026.3698893","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3698893","url":null,"abstract":"Rapid on-site monitoring of free chlorine is precarious for maintaining drinking water quality and public health. This work presents a portable microfluidic integrated chemiluminescence (L) device for free chlorine detection in tap water with a compact, smartphone-based optical readout. The microfluidic architecture enables efficient on-chip mixing of the water sample and CL reagents within a small reaction volume, ensuring reproducible signal generation with minimal reagent consumption. CL emission from the chlorine-induced reaction is captured with a smartphone camera in a 3D-printed device, and quantitative analysis is performed via image-based intensity extraction. The performance of the proposed device was systematically evaluated using both tap water and deionized (DI) water to assess matrix effects. A clear concentration-dependent CL response was obtained in both media, with a wider linear range of 20–100 μM and a lower limit of detection of 16.4 μM for tap water, compared to a linear range of 20–70 μM and a detection limit of 15.1 μM for DI water. The experimental results demonstrate the robustness and practical applicability of the developed portable CL platform for field-deployable free chlorine monitoring under real water conditions.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"3503604-3503604"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148504922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biaxial Optical Cantilever Combining On-Chip Patterned Laser and Sampling Moiré Method","authors":"Soya Sato;Toshihiro Shiratori;Kazuyoshi Hirose;Hiroki Kumon;Hiroki Kamei;Shu Honma;Yuki Okamoto;Yusuke Takei;Hidetoshi Takahashi","doi":"10.1109/LSENS.2026.3699273","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3699273","url":null,"abstract":"The optical lever method is a widely used high-resolution displacement sensing technique in various micro- and nanoscale sensing systems. In this method, cantilever displacement is evaluated by detecting changes in the position of reflected light using a photodiode; however, precise optical alignment is required during setup. To address this issue, optical lever systems combining a cantilever with the sampling Moiré (SM) method have been proposed. More recently, approaches using on-chip pattern lasers that directly project periodic patterns have attracted attention, as they simplify both system configuration and cantilever fabrication. In many applications, not only normal displacement but also torsional deformation must be measured to evaluate multiaxis forces and moments. Although the SM method is well suited for analyzing 2-D periodic patterns, generating well-defined 2-D lattice patterns using mechanical gratings is technically challenging. In this study, we propose a biaxial optical cantilever sensor that integrates the SM method with an on-chip pattern laser capable of directly projecting a 2-D checkerboard pattern. The projected pattern was captured using a lens-less camera and analyzed using the SM method. Experimental results confirmed that the checkerboard pattern shifted independently in two directions depending on the force application point. The achieved resolutions were 32.4 nN for the normal force <inline-formula><tex-math>${{F}_z}$</tex-math></inline-formula>and 201 μN·μm for the bending moment <inline-formula><tex-math>${{M}_x}$</tex-math></inline-formula>, demonstrating the feasibility of simple and high-resolution two-axis force measurement.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"2503504-2503504"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148505039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IEEE Sensors Letters Publication Information","authors":"","doi":"10.1109/LSENS.2026.3710954","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3710954","url":null,"abstract":"","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"0201901-0201901"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11614967","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148627318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetoelectric Sensor With Sensitive Unit Based on Composite Structure of Magneto-Sensitive Elastomer and Polyvinylidene Fluoride for Rotational Speed Detection","authors":"Benxiang Ju;Song Li;Benyuan Fu;Qi Mai;Bing Lv","doi":"10.1109/LSENS.2026.3694484","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3694484","url":null,"abstract":"Rotational speed sensors are critical for operational monitoring and fault diagnosis across various domains, including automotive engineering, industrial machinery, and aerospace. This letter presents a sensitive unit composed of a magneto-sensitive elastomer (MSE) and polyvinylidene fluoride (PVDF), hereafter referred to as the MSE/PVDF sensitive unit (MPSU). Owing to the excellent magneto-sensitive properties of MSE, the PVDF component within the designed MPSU generates a piezoelectric effect when the MSE was exposed to a magnetic field. By processing this output signal, the rotational speed can be accurately determined. Dynamic magnetoelectric performance tests and speed detection experiments were conducted to thoroughly evaluate its sensing capability. Experimental results indicate that, in contrast to conventional Hall sensors, the proposed MPSU delivers highly accurate rotational speed detection while operating independent of external power supply. This design offers a promising pathway for deploying rotational speed sensors in energy-constrained environments.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"2502804-2502804"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148442516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Detection of Naproxen Surface Residue Using FTIR Spectroscopy and Partial Least Squares Regression","authors":"Mehdi Faraz;Jukka Heikkonen;Tuomas Ranti;Anna Savola;Susanna Heikkinen;Eero Kiljunen;Tuomas Mäkilä","doi":"10.1109/LSENS.2026.3697991","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3697991","url":null,"abstract":"Cleaning validation is essential in pharmaceutical manufacturing to prevent cross-contamination, yet traditional wipe-sampling and chromatographic methods are labor-intensive and time-consuming. This study demonstrates handheld Fourier transform infrared (FTIR) spectroscopy combined with partial least squares (PLS) regression as a rapid, nondestructive alternative for quantifying naproxen surface residue on stainless steel. A total of 293 FTIR spectra were collected from stainless steel coupons spiked with naproxen (0 to 5.15 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>) over 650 cm<inline-formula><tex-math>$^{-1}$</tex-math></inline-formula>–4000 cm<inline-formula><tex-math>$^{-1}$</tex-math></inline-formula>. After outlier removal (IQR method), 263 spectra were retained and preprocessed using Savitzky–Golay smoothing and standard normal variate (SNV) normalization. The global PLS model (fivefold CV) achieved <inline-formula><tex-math>$R^{2} = 0.854$</tex-math></inline-formula>, RMSE = 0.491 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>, limit of detection (LOD) = 1.95 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$ ^{-2} $</tex-math></inline-formula>, and limit of quantification (LOQ)= 5.92 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>. Interval PLS identified the 1646–1810 cm<inline-formula><tex-math>$^{-1}$</tex-math></inline-formula> region (naproxen C = O stretch) as most predictive, yielding markedly improved performance: <inline-formula><tex-math>$R^{2} = 0.973$</tex-math></inline-formula>, RMSE = 0.211 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>, LOD = 0.716 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>, and LOQ = 2.169 <inline-formula><tex-math>$mu$</tex-math></inline-formula>g cm<inline-formula><tex-math>$^{-2}$</tex-math></inline-formula>. These results demonstrate that chemometric interval selection substantially enhances sensitivity and chemical interpretability, establishing handheld FTIR-interval partial least squares as an efficient, nondestructive alternative for routine pharmaceutical cleaning verification.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"4502004-4502004"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11537396","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148504925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"For Miniaturized Gas Chromatographs: An Acquisition Module With a High-Stability Constant-Current Source for Microthermal Conductivity Detectors","authors":"Shunlong Xu;Shaojie Ma;Wenbo Li;Zhirui Li;Fei Feng","doi":"10.1109/LSENS.2026.3701970","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3701970","url":null,"abstract":"Miniaturized gas chromatographs (GCs) are ideal for in situ detection due to their compact size and low power consumption. The microelectromechanical systems-based micro-thermal conductivity detector (μTCD) is widely used in these systems. Its acquisition module typically includes an excitation source, protection circuitry, and differential acquisition circuitry. A constant current excitation reduces signal nonlinearity more effectively than constant voltage excitation, while its high stability significantly suppresses output noise. This letter presents a voltage-controlled constant-current source (VCCS) and analyzes the factors influencing its stability. Experimental results demonstrated that the VCCS outperformed commercial alternatives. At 50 mA, the current fluctuation remained within 3 <italic>μ</i>A over 12 h—approximately one-tenth that of commercial products. The VCCS achieved a maximum accuracy of 0.0035% full scale and a relative standard deviation (RSD) of 0.0011%. This module provides a reliable solution for miniaturized GC design. Tests using light hydrocarbons (20–2000 ppm) showed a peak area RSD below 3.8% and excellent linearity with concentration. Comparative tests with a commercial GC module showed that, at an excitation current of 50 mA and a 10 ppm gas concentration, the proposed module provided better detection capabilities. It enabled clear observation of chromatographic peaks and achieved a limit of detection of 6 ppm for propane.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"2503004-2503004"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148505766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate On-Body Distance Estimation Using BLE RSSI and IMU Sensor Fusion","authors":"Aksh Rajput;Anik Sarker;Alan T. Asbeck","doi":"10.1109/LSENS.2026.3701850","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3701850","url":null,"abstract":"It is useful to estimate on-body distances for human motion tracking and rehabilitation monitoring. We perform accurate short-range (<inline-formula><tex-math>$&lt; $</tex-math></inline-formula>1 m) distance estimation by fusing bluetooth low energy received signal strength indicator (RSSI) with inertial measurement unit (IMU) orientation data. We developed a custom wearable system using ESP32 microcontrollers and IMUs and conducted a study with N = 6 participants performing a series of defined arm movements. We trained a long short-term memory (LSTM) model, termed QuaternionRNN, which leverages temporal sequences of normalized quaternions and RSSI to predict the distance between sensors on the waist and wrist. The model achieved a median absolute distance error of ~3 cm on a generalized dataset, and between 4 and 7 cm in subjectwise cross-validation. We compared this to unscented Kalman filters with RSSI alone and RSSI plus orientation, and an RSSI-only LSTM, and found QuaternionRNN to have 2–4x lower errors. This work establishes a cost-effective and accurate solution for short-range nonline-of-sight distance sensing.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"6006504-6006504"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148442707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Noise-Limited Broadband Optical Sensing Performance in Si1-xGex Nanowire Schottky-Barrier Reconfigurable Phototransistors","authors":"Vikash Sharma;Nitish Kumar;Ankur Gupta;Samaresh Das","doi":"10.1109/LSENS.2026.3701772","DOIUrl":"https://doi.org/10.1109/LSENS.2026.3701772","url":null,"abstract":"A complementary metal–oxide–semiconductor (CMOS)-compatible Schottky barrier (SB)-based Si_1-xGe_x nanowire reconfigurable phototransistors (RPTs) are demonstrated for broadband ultraviolet (UV), visible, and near-infrared optical sensing. The device operates via SB modulation: reverse bias thermionic emission increases through optical generation and barrier lowering, while forward bias results in field-emission-dominated conduction with negligible photoresponse. The energy bandgap is systematically modulated by varying the Ge content (x = 0, 0.52, 0.72, 0.89, and 1), thereby enhancing the spectral response. For n-type operation, the peak responsivity shifts from 308 mA/W at 350 nm for Si (x = 0) to 357 mA/W at 500 nm, while a responsivity of 99.4 mA/W is achieved at 710 nm for Ge (x = 1), compared to ∼3 mA/W for Si, thereby expanding the effective spectral bandwidth by ∼184 nm. Very low noise is observed as a function of frequency, initially showing a plateau followed by Lorentzian behavior, with minimum noise-equivalent power values of 1.2 × 10⁻¹² W/Hz^1/2 for Si and 2.81 × 10⁻¹⁰ W/Hz^1/2 for Ge, yielding peak specific detectivity of ∼3 × 10⁶ Jones in the UV region. Despite an ultra-scaled active area (∼10⁻¹¹ cm²), the SB-RPT offers high-sensitivity broadband optical sensing suitable for weak signals in CMOS-integrated photonic platforms.","PeriodicalId":13014,"journal":{"name":"IEEE Sensors Letters","volume":"10 7","pages":"3503704-3503704"},"PeriodicalIF":2.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148505034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}