Flexible Micro-Scale Sensor Array for Non-Contact Electric Potential Imaging

Flexible triboelectric sensor array based on 3D printed bead-on-string sacrificial layer for human-machine interactions

Flexible planar electromagnetic sensor array fabricated with printing electronic technology

Flexible pressure sensor arrays have emerged as a key enabling technology in the era of the Internet of Things and artificial intelligence, offering real-time, distributed, and multidimensional sensing capabilities. The micro/nano-engineered sensor arrays, composed of numerous integrated sensing units, show tremendous potential in human-machine interactions. However, meeting the increasing demands for high-resolution, high-performance area sensing presents critical challenges, including the fabrication of high-density arrays, mitigation of signal crosstalk, and the integrated optimization of sensing performance. This paper briefly summarizes and reviews the existing research strategies of flexible sensor arrays, from high-density sensor array manufacturing technology, anti-crosstalk design of multi-pixel units, performance control methods for sensing units, to intelligent human-machine interaction applications. Finally, a future outlook is proposed in light of the current state to promote the wider application of sensing arrays in human-machine interactions.

An interactive surface using bending gestures as the input is proposed by integrating a flexible strain sensor array and a flexible display screen. To create such a flexible strain sensor array, formation of a reliable interconnection between the elastic sensitive regions and the rigid contact regions is vital to achieve required sensitivity and durability. In this work, a new design with an added interconnect layer on top of the interface regions is used to reduce the bending induced local stress. A stretchable conductive composite by blending carbon black (CB) with polydimethylsiloxane (PDMS) and Ecoflex (CB‐PDMS/Ecoflex) is developed for the interconnect layer. CB‐PDMS/Ecoflex is compatible with the blade coating for facile processing, and demonstrates a similar low Young's modulus as that of the sensitive region composed of silver nanowires and PDMS. Printing processes are developed to fabricate a 4 × 9 flexible strain sensor array based on the proposed design and the interconnect layer. It is shown that the sensor with CB‐PDMS/Ecoflex interconnect layer can sustain more than 3000 bending cycles. Finally, the sensor array is integrated with a flexible active‐matrix organic light‐emitting diode display to construct the bendable interactive surface, demonstrating the capability of controlling the ball movement via bending gestures.

This study presents an unique process to integrate the temperature sensing/heating elements, multi-layer through-hole vias (THVs), and electrical routings on parylene substrate to implement a multi-functional flexible temperature sensor array. Moreover, the polymer-staking processes with 3D electrical routings enable the further integration of various devices. In application, this study also demonstrates the implementation and integration of flexible temperature sensor array by: (1) temperature distribution and contour measurement using 4×4 temperature sensor array, (2) temperature monitoring and control using the integration of Pt-sensor and Pt-heater, (3) heterogeneous integration of temperature sensor array with LED-chip for LED temperature monitoring, and (4) 3D integration of temperature sensor array with LED and micro-lens and micro chamber.

Electrostatic discharge prevention system via body potential control based on a triboelectric nanogenerator

Achieving a balance between high spatial resolution, minimal crosstalk, and long-term stability remains a critical challenge in the design of flexible tactile sensor arrays for robotic applications. While increasing array density enhances perception, it often compromises signal integrity due to mechanical coupling. To address these conflicting objectives, this paper proposes a multi-objective co-design strategy for a finger-interdigitated piezoresistive sensor based on carbon nanotubes and polyimide. Using the COMSOL Multiphysics simulation platform, the performance of three array density configurations—2 × 2, 3 × 3, and 4 × 4—under static pressure and creep conditions was systematically analyzed. A key theoretical finding is that the normalized piezoresistive sensitivity remains independent of array density, demonstrating the excellent scalability of the proposed architecture. Performance trade-offs, however, are significant: the low-density (2 × 2) array offers superior mechanical isolation but suffers from greater long-term drift, while the high-density (4 × 4) array provides the best creep resistance and wide-range stability at the cost of higher crosstalk. A comprehensive evaluation reveals that the 3 × 3 array achieves an optimal balance, with moderate crosstalk and excellent stability, making it the most suitable configuration for practical applications such as robotic fingers that require both sensing accuracy and reliability. This study provides a theoretical foundation and design guidelines for optimizing the trade-offs in high-density flexible skins.

This paper presents the first multiparametric flexible sensor arrays system for in situ immediate diagnosis of glossitis, which may furnish clues for certain systemic diseases. The system includes a multiparametric flexible sensor array and accompanying signal processing circuitry. The flexible sensor arrays are obtained by facile micro-fabrication and chemical modifications. The sensors are affixed to the tongue mucosa for simultaneous monitoring the signals of sodium, potassium, pH, and temperature variations, which are transmitted to a smart terminal via the circuitry. In vitro tests have demonstrated excellent response linearity, sensitivity, selectivity, and reproducibility of this sensor arrays system. The signal processing circuitry provides reliable support for integrated testing of multiparametric sensors. Simulating the tongue state with agar, the system significantly detected changes in marker levels from the exudate on the agar surface. The multiparametric flexible sensor arrays system is expected to tackle the “black box” issues in several clinical diagnostics in the future.

A large area and mechanically flexible active matrix image sensor array is made by integrating organic photo diode (OPDs) onto a high resolution organic thin-film transistor (OTFT) backplane on plastic substrate. The maximum process temperature is less than 100 °C. The sensor array has an imaging area of 130 mm × 130 mm and resolution of 1536 ×1536 (~300 ppi), which, to our best knowledge, is a state-of-the-art result among all reported all organic active matrix image sensor arrays.

Detecting volatile organic compounds (VOCs) in human breath is critical for the early diagnosis of diseases. Good selectivity of VOC sensors is crucial for the accurate analysis of VOC biomarkers in human breath, which consists of more than 200 types of VOCs. In this paper, a flexible virtual sensor array (FVSA) was proposed based on a sensing layer of MXene and laser-induced graphene interdigital electrodes (LIG-IDEs) for detecting VOCs in exhaled human breath. The fabrication of LIG-IDEs avoids the costly and complicated procedures required for the preparation of traditional IDEs. The FVSA's responses of multiple parameters help build a unique fingerprint for each VOC, without a need for changing the temperature of the sensing element, which is commonly used in the VSA of semiconductor VOC sensors. Based on machine learning algorithms, we have achieved highly precise recognition of different VOCs and mixtures and accurate prediction (accuracy of 89.1%) of the objective VOC's concentration in variable backgrounds using this proposed FVSA. Moreover, a blind analysis validates the capacity of the FVSA to identify alcohol content in human breath with an accuracy of 88.9% using breath samples from volunteers before and after alcohol consumption. These results show that the proposed FVSA is promising for the detection of VOC biomarkers in human exhaled breath and early diagnosis of diseases.

Flexible hot film sensor array was developed for underwater applications. To minimize conductive heat loss to substrate, heighten sensitivity and shorten response time nickel thin film resistors are fabricated on polyimide substrate. Fully flexible structure and very low thickness of the sensing belt enable it possible to be taped on highly curved surfaces to measure fluid parameters with minimal invasion. Polymer compatible micromachining technologies with further consideration of waterproof coating were developed. High temperature coefficient of resistance (TCR) and low time constant of sensor were obtained. A hydrodynamic experimental setup was established, and a demonstration indicated flow velocity can be measured with the sensor.

A Flexible Self-Powered Occlusal Force Sensor Array for Assisting Oral Occlusion Reconstruction

Recent progress in high-resolution tactile sensor array: From sensor fabrication to advanced applications

In this paper, we present a novel flexible sensor array manufacturing process that involves transfer printing methods using a chip mounter with a vacuum collet. We successfully transfer-printed continuously very fragile microelectromechanical systems (MEMS)-based 5-mm-long, 1-mm-wide, 5-µm-thick high-aspect-ratio ultra-thin PZT(1.9µm)/Si(3µm) strain sensors onto a polyimide based flexible printed-circuit (FPC) substrate with etched Cu wiring. Then, we connected the sensors to the Cu wiring by printing insulating and conductive pastes using a screen printer. The output voltage based on the deformation behavior of the test plate was generated from the flexible piezoelectric strain sensor array attached to the plate. Therefore, the developed piezoelectric sensor array is capable of easily performing the distribution measurement of the strain leading to damage such as cracks.

Sorts of Li-ion batteries (LIB) have been becoming important energy supply and storage devices. As a long-standing obstacle, safety issues are limiting the large-scale adoption of high-energy–density batteries. Strategies covering materials, cell, and package processing have been paid much attention to. Here, we report a flexible sensor array with fast and reversible temperature switching that can be incorporated inside batteries to prevent thermal runaway. This flexible sensor array consists of PTCR ceramic sensors combined with printed PI sheets for electrodes and circuits. Compared to room temperature, the resistance of the sensors soars nonlinearly by more than three orders of magnitude at around 67 °C with a 1 °C/s rate. This temperature aligns with the decomposition temperature of SEI. Subsequently, the resistance returns to normal at room temperature, demonstrating a negative thermal hysteresis effect. This characteristic proves advantageous for the battery, as it enables a lower-temperature restart after an initial warming phase. The batteries with an embedded sensor array could resume their normal function without performance compromise or detrimental thermal runaway.