Flexible Sensor System Research Articles

Review of 3D-printing technologies for wearable and implantable bio-integrated sensors.

Thin-film microfabrication-based bio-integrated sensors are widely used for a broad range of applications that require continuous measurements of biophysical and biochemical signals from the human body. Typically, they are fabricated using standard photolithography and etching techniques. This traditional method is capable of producing a precise, thin, and flexible bio-integrated sensor system. However, it has several drawbacks, such as the fact that it can only be used to fabricate sensors on a planar surface, it is highly complex requiring specialized high-end facilities and equipment, and it mostly allows only 2D features to be fabricated. Therefore, developing bio-integrated sensors via 3D-printing technology has attracted particular interest. 3D-printing technology offers the possibility to develop sensors on nonplanar substrates, which is beneficial for noninvasive bio-signal sensing, and to directly print on complex 3D nonplanar organ structures. Moreover, this technology introduces a highly flexible and precisely controlled printing process to realize patient-specific sensor systems for ultimate personalized medicine, with the potential of rapid prototyping and mass customization. This review summarizes the latest advancements in 3D-printed bio-integrated systems, including 3D-printing methods and employed printing materials. Furthermore, two widely used 3D-printing techniques are discussed, namely, ex-situ and in-situ fabrication techniques, which can be utilized in different types of applications, including wearable and smart-implantable biosensor systems.

Active‐Matrix‐Based Flexible Optical Image Sensor

AbstractOwing to the demand for the development of Internet of things devices, multiple sensor platforms are of great interest to society and its future electronics. One of these emerging devices is a mechanically flexible sensor system that can attach and conform to nonplanar surfaces, unlike conventional inflexible sensor chips. To realize this concept, a variety of flexible sensor systems must be developed from materials to system integrations. This study proposes a flexible sensor system as one of the candidates: an active‐matrix‐based flexible optical image sensor that uses a stacked nanosheet film formed by a solution process and transistors. The results show that the sensor can be utilized as an optical imager because it detects enough optical stimuli. In addition to the sensitivity, the mechanical flexibility of the active‐matrix optical sensor is tested, and the results exhibit good electrical stability even after 1000 bending cycles and 0.85 cm bending radius. The mapping of light distribution is successfully demonstrated under both flat and curved conditions. This flexible optical sensor array shows the high possibility to image the light distribution for high‐resolution and low power mapping realized by active matrix circuit integration.

Sensation and Perception of a Bioinspired Flexible Smart Sensor System.

The somatosensory system helps the human body to become aware of various stimuli and to interact with its surroundings. Humans are able to identify and to process abundant sensory information quickly due to their unique perception characteristics. As the largest sensory organ, skin has a large number of discrete receptors to sense and to transform stimuli of touch, pressure, pain, temperature, etc. into electrical signals, which are preprocessed at various levels before reaching the brain, greatly reducing the computational burden on the central nervous system. In addition, the conduction speed varies for different stimulus information, which simplifies the parallel processing of a variety of information. In this Perspective, we discuss a bioinspired design for a flexible smart sensor system by simulating the human somatosensory system. In this design, sensors with selective responses, signals separated in time sequences, and hierarchical information processing are adopted to optimize the sensing and perceiving processes, to reduce power consumption, and to improve the speed of a flexible smart sensor system.

Wireless and Flexible Skin Moisture and Temperature Sensor Sheets toward the Study of Thermoregulator Center.

A disorder in the thermoregulator center in a human body leads to some potential diseases such as fever and hyperthyroidism. To predict these diseases early, monitoring the health condition of the human body due to the influence of thermoregulation disorders is important. Although extensive works are performed on sweat-rate detection by constructing microfluidic channels, skin-moisture evaporation before sweating remains unknown. This work proposes a wireless and flexible sensor sheet to investigate the thermoregulatory responses of different people under cold stimulation and exercise by measuring the temperature and moisture variations on the finger skin. An integrated flexible sensor system consists of a ZnIn2 S4 nanosheet-based humidity sensor and carbon nanotube/SnO2 temperature sensor. The results exhibit distinct thermoregulation abilities of five volunteers. Interestingly, the sudden increase in finger moisture that results from the excitation by the sympathetic nerve is observed during the cold-stimulus test. Although further studies are required to predict the potential diseases resulted from thermoregulation disorders in human body, this study provides a possibility of continuous and real-time monitoring of thermoregulatory activities via skin moisture and temperature detection using a flexible sensor sheet.

Multimodal Wearable Sensor Sheet for Health-Related Chemical and Physical Monitoring.

Continuous multiple data health monitoring has high potential to detect abnormal conditions or early stages of diseases in the future. To monitor a continuous small vital signal, one of the promising architectures is an attachable flexible multimodal sensor system, which can detect multiple health conditions from the skin surface. Recent breakthroughs have realized continuous sweat chemicals or physical conditions using flexible sensors. However, multimodal sensor integration to monitor chemical and physical information simultaneously and precisely is still a challenge. In this study, we present a multimodal wearable sensor sheet, which allows us to monitor sweat glucose, electrocardiograms, and skin temperature. Furthermore, to prevent the accumulation of glucose on the sensor surface for precise monitoring, a fluidic channel is also integrated to refresh the sweat from the sensor surface, resulting in the precise measurement of chemical substances in real time. This multimodal and flexible sensor platform takes a significant step toward realizing wearable healthcare applications to diagnose the early stages of diseases in advance.

Flexible Potentiometric Sensor System for Non-Invasive Determination of Antioxidant Activity of Human Skin: Application for Evaluating the Effectiveness of Phytocosmetic Products

In contemporary bioanalysis, monitoring the antioxidant activity (AOA) of the human skin is used to assess stresses, nutrition, cosmetics, and certain skin diseases. Non-invasive methods for skin AOA monitoring have certain advantages over invasive methods, namely cost-effectiveness, lower labor intensity, reduced risk of infection, and obtaining results in the real-time mode. This study presents a new flexible potentiometric sensor system (FPSS) for non-invasive determination of the human skin AOA, which is based on flexible film electrodes (FFEs) and membrane containing a mediator ([Fe(CN)6]3–/4–). Low-cost available materials and scalable technologies were used for FFEs manufacturing. The indicator FFE was fabricated based on polyethylene terephthalate (PET) film and carbon veil (CV) by single-sided hot lamination. The reference FFE was fabricated based on PET film and silver paint by using screen printing, which was followed by the electrodeposition of precipitate containing a mixture of silver chloride and silver ferricyanide (SCSF). The three-electrode configuration of the FPSS, including two indicator FFEs (CV/PET) and one reference FFE (SCSF/Ag/PET), has been successfully used for measuring the skin AOA and evaluating the impact of phytocosmetic products. FPSS provides reproducible (RSD ≤ 7%) and accurate (recovery of antioxidants is almost 100%) results, which allows forecasting its broad applicability in human skin AOA monitoring as well as for evaluating the effectiveness of topically and orally applied antioxidants.

A Wearable Body Condition Sensor System with Wireless Feedback Alarm Functions.

Emerging feedback systems based on tracking body conditions can save human lives. In particular, vulnerable populations such as disabled people, elderly, and infants often require special care. For example, the high global mortality of infants primarily owing to sudden infant death syndrome while sleeping makes request for extraordinary attentions in neonatal intensive care units or daily lives. Here, a versatile laser-induced graphene (LIG)-based integrated flexible sensor system, which can wirelessly monitor the sleeping postures, respiration rate, and diaper moisture with feedback alarm notifications, is reported. A tilt sensor based on confining a liquid metal droplet inside a cavity can track at least 18 slanting orientations. A rapid and scalable laser direct writing method realizes LIG patterning in both the in-plane and out-of-plane configurations as well as the formation of nonstick conductive structures to the liquid metal. By rationally merging the LIG-based tilt, strain, and humidity sensors on a thin flexible film, the multimodal sensor device is applied to a diaper as a real-time feedback tracking system of the sleeping posture, respiration, and wetness toward secure and comfortable lives. User-friendly interfaces, which incorporate alarming functions, provide timely feedback for caregivers tending to vulnerable populations with limited self-care capabilities.

Fully Flexible Textile Antenna-Backed Sensor Node for Body-Worn UWB Localization

A mechanically flexible textile antenna-backed sensor node is designed and manufactured, providing accurate personal localization functionality by application of Decawave’s DW1000 Impulse Radio Ultra-Wideband (IR-UWB) Integrated Circuit (IC). All components are mounted on a flexible polyimide foil, which is integrated on the backplane of a wearable cavity-backed slot antenna designed for IR-UWB localization in Channels 2 and 3 of the IEEE 802.15.4-2011 standard (3744 MHz–4742.4 MHz). The textile antenna’s radiation pattern is optimized to mitigate body effects and to minimize absorption by body tissues. Furthermore, its time-domain characteristics are measured to be adequate for localization. By combining the antenna and the bendable Printed Circuit Board (PCB), a mechanically supple sensor system is realized, for which the performance is validated by examining it as a node used in a complete localization system. This shows that six nodes around the body must be deployed to provide system coverage in all directions around the wearer. Even without using sleep mode functionalities, the measurements indicate that the system’s autonomy is 13.3 h on a 5 V 200 mAh battery. Hence, this system acts as a proof of concept for the joining of localization electronics and other sensors with a full-textile antenna into a mechanically flexible sensor system.

All-in-one, wireless, fully flexible sodium sensor system with integrated Au/CNT/Au nanocomposites

Abstract Advancements in functional nanomaterials and wearable electronics have demonstrated the use of solid-state ion-selective electrodes (SS-ISEs) for human health applications. Existing devices, however, still rely on separate and multiple components of flexible sensors, interconnectors, and rigid data acquisition units, which limits the wearability of the entire system on the skin for continuous analyte monitoring. Here, this paper introduces an all-in-one, wireless, fully flexible, sodium detection system that integrates gold-carbon nanotube-gold (Au/CNT/Au) sensors and flexible thin-film circuits, together on a soft elastomeric membrane. The nanocomposite sensor includes electrochemically deposited Au nanoparticles on a CNT transducer to improve the conductivity, capacitance, and interfacial contact between materials. A set of experimental electrochemical analysis confirms the high stability of the SS-ISE based on Au/CNT/Au nanocomposites. At the same time, the thin-film system shows mechanical robustness and reliability, even with repetitive bending up to 500 cycles. The fully flexible, sensor-circuit integrated system demonstrates stable sodium measurements when mounted on the skin with minimized motion artifacts. The measured sensitivity of the sodium sensor is 55.5 ± 0.3 mV/decade, along with less than 3% change when the entire device is mounted on the skin with continuous movements. Overall, the presented comprehensive study, including nanomaterials, nano-microfabrication, electrochemistry, and electronics, shows the enormous potential of the wireless all-in-one sensor system for seamless integration with various types of skin-mounted wearable health monitors.

Co@N-CNT/MXenes in situ grown on carbon nanotube film for multifunctional sensors and flexible supercapacitors.

The rapid development of human-machine interfaces and artificial intelligence is dependent on flexible and wearable soft devices such as sensors and energy storage systems. One of the key factors for these devices is the design of a flexible electrode with high sensitivity, fast response time, and a wide working range. Here, we report the fabrication of strain sensors and all-solid-state flexible supercapacitors using Co@N-CNT/MXenes as an electrode material. The manufactured sensor shows a high tensile range (strain up to 200%) and high stability. The resistance change caused by the fingers touching the sensor can be used to transmit the Morse code information. Flexible supercapacitors serving as power supply demonstrate excellent cycling stability (85 000 cycles) and coulombic efficiency (99.7%) for their high surface area and pseudocapacitance. A self-powered integrated system composed of the strain sensor and flexible supercapacitor is fabricated and operates stably in a wide strain sensing test range. Moreover, the flexible solar-charging self-powered integrated system could be attached to the human body for stable human motion detection. This study clearly shows that appropriate selection of a single functional material to enable it to be used in multi-functional sensors and supercapacitors can simplify the process and reduce the cost of manufacturing wearable devices.

Flexible and disposable gold nanoparticles-N-doped carbon-modified electrochemical sensor for simultaneous detection of dopamine and uric acid

Catalytic and electrocatalytic applications of supported metal nanoparticles are hindered due to an aggregation of metal nanoparticles and catalytic leaching under harsh operations. Hence, stable and leaching free catalysts with high surface area are extremely desirable but also challenging. Here we report a gold nanoparticles-hosted mesoporous nitrogen doped carbon matrix, which is prepared using bovine serum albumin (BSA) through calcination. BSA plays three roles in this process as a reducing agent, capping agent and carbon precursor, hence the protocol exhibits economic and sustainable. Gold nanoparticles at N-doped BSA carbon (AuNPs@NBSAC)-modified three-electrode strip-based flexible sensor system has been developed, which displayed effective, sensitive and selective for simultaneous detection of uric acid (UA) and dopamine (DA). The AuNPs@NBSAC-modified sensor showed an excellent response toward DA with a linear response throughout the concentration range from 1 to 50 μM and a detection limit of 0.05 μM. It also exhibited an excellent response toward UA, with a wide detection range from 5 to 200 μM as well as a detection limit of 0.1 μM. The findings suggest that the AuNPs@NBSAC nanohybrid reveals promising applications and can be considered as potential electrode materials for development of electrochemical biosensors.

Flexible Assemblies of Electrocapacitive Volume Tomographic Sensors for Gauging Fuel of Spacecraft

Gauging propellant fuel of spacecraft in outer space has been an issue, because their liquid fuels tend to float, slosh, adhere to the tank walls, and form bubbles under low-gravity conditions. For this reason, conventional fuel gauging techniques may not be an accurate way of gauging the fuel in space. In this paper, we report a flexible monolithic printed assembly of electrocapacitive volume tomography sensors, which can reconstruct the three-dimensional shape of the propellant fuel and promise to overcome the deficiencies of conventional fuel-gauging techniques. A commercial printer was used to transfer the patterns of the electrocapacitive volume tomography sensors and electric connections onto a flexible laminated copper. Feasibility of the three-dimensional volumetric reconstruction on water and a heat-transfer fluid showed that the National Institute of Standards and Technology’s flexible electrocapacitive volume tomography sensor system could successfully sense the changes in electrocapacitance due to the presence of these liquids. Based on those measured electrocapacitive volume tomography data, the three-dimensional shape of the fluid was reconstructed and matched with the real one used during laboratory testing.

Multimodal Plant Healthcare Flexible Sensor System.

The rising global human population and increased environmental stresses require a higher plant productivity while balancing the ecosystem using advanced nanoelectronic technologies. Although multifunctional wearable devices have played distinct roles in human healthcare monitoring and disease diagnosis, probing potential physiological health issues in plants poses a formidable challenge due to their biological complexity. Herein an integrated multimodal flexible sensor system is proposed for plant growth management using stacked ZnIn2S4(ZIS) nanosheets as the kernel sensing media. The proposed ZIS-based flexible sensor can not only perceive light illumination at a fast response (∼4 ms) but also monitor the humidity with a perdurable steady performance that has yet to be reported elsewhere. First-principles calculations reveal that the tunneling effect dominates the current model associated with humidity response. This finding guides the investigation on the plant stomatal functions by measuring plant transpiration. Significantly, dehydration conditions are visually recorded during a monitoring period (>15 days). This work may contribute to plant-machine biointerfaces to precisely manage plant health status and judiciously utilize limited resources.

Ultrathin Ion-Sensitive Field-Effect Transistor Chips with Bending-Induced Performance Enhancement.

Flexible multifunctional sensors on skin or wearables are considered highly suitable for next-generation noninvasive health care devices. In this regard, the field-effect transistor (FET)-based chemical sensors such as ion-sensitive FETs (ISFETs) are attractive as, with the ultrathin complementary metal oxide semiconductor technology, they can enable a flexible or bendable sensor system. However, the bending-related stress or strain could change the output of devices on ultrathin chips (UTCs), and this has been argued as a major challenge hindering the advancement and use of this technology in applications such as wearables. This may not be always true, as with drift-free ISFETs, we show that bending could also enhance the performance of UTCs. Through fine control of bending radius in the micrometer scale, the mechanically flexible RuO2-based ISFETs on UTCs (44.76 μm thickness) are shown to reproducibly enhance the performance even after 1000 bending cycles. The 1.3 orders of magnitude improved stability (the drift rate changed from −557 nA/min to −28 ± 0.16 nA/min) is observed over a time period of 417.3 s (∼7 min) at fixed biasing and temperature conditions and under different pH conditions. Finally, a compact macromodel is developed to capture the bending-induced improvements in flexible ISFETs. The performance enhancement by controlled bending of devices could generally benefit the rapidly growing field of flexible electronics.

Matrix-Addressed Flexible Capacitive Pressure Sensor With Suppressed Crosstalk for Artificial Electronic Skin

Matrix-addressed flexible pressure sensors, being able to accurately measure both local contact force and spatial distribution, are pursued for many electronic skin applications. One key issue to be addressed is that the local force being applied onto the target areas may be passed to the neighboring pixels through deformation of the touched top electrode layer. It causes significant signal crosstalk and also loss of measurement accuracy. A new top electrode layer structure is proposed with the development of processes for matrix-addressed pressure sensor systems. It is composed of a patterned layer of high Young’s modulus and a low-modulus encapsulation layer. The former is able to sustain a relatively high processing temperature for forming reliable and high-density electrical connections. The latter is to protect the patterned layer while having low Young’s modulus to minimize the spreading of local deformation at the pressed pixel to the surrounding ones. A $10 \times 10$ matrix-addressed flexible capacitive pressure sensor system is constructed to verify this design, showing effective suppression of the pixel-to-pixel signal crosstalk and improvement of measurement accuracy. The flexible pressure sensor system is integrated onto a prosthetic hand, showing capabilities of differentiating details of massage balls.

Wireless, Flexible, Ion-Selective Electrode System for Selective and Repeatable Detection of Sodium.

Wireless, flexible, ion-selective electrodes (ISEs) are of great interest in the development of wearable health monitors and clinical systems. Existing film-based electrochemical sensors, however, still have practical limitations due to poor electrical contact and material–interfacial leakage. Here, we introduce a wireless, flexible film-based system with a highly selective, stable, and reliable sodium sensor. A flexible and hydrophobic composite with carbon black and soft elastomer serves as an ion-to-electron transducer offering cost efficiency, design simplicity, and long-term stability. The sensor package demonstrates repeatable analysis of selective sodium detection in saliva with good sensitivity (56.1 mV/decade), stability (0.53 mV/h), and selectivity coefficient of sodium against potassium (−3.0). The film ISEs have an additional membrane coating that provides reinforced stability for the sensor upon mechanical bending. Collectively, the comprehensive study of materials, surface chemistry, and sensor design in this work shows the potential of the wireless flexible sensor system for low-profile wearable applications.

(Invited) Multi-Functional Flexible Sensor Sheets

Flexible and stretchable electronics are now widely studied for a next class of electric devices replaced from the silicon-based conventional inflexible devices. In particular, multi-functional e-skins can contribute to the applications for wearable healthcare devices and Internet of Things (IoT) concepts. For healthcare application, chemical information such as pH, glucose, sodium ion, and potassium ion levels are very important to monitor as well as physical information including activity, temperature, heartbeat, and electrocardiogram (ECG) signals. Furthermore, simultaneous multiple condition monitoring of physical and chemical information is a next class of wearable devices for convenient and safe human life. To realize the multi-functional flexible sensor system platforms, in this talk, flexible physical and chemical sensor sheets using mainly inorganic nanomaterials will be discussed by proposing low-cost, macroscale, and multi-functional material systems. Especially, human-interactive flexible sensors to detect human motion and health conditions are mainly introduced. After understanding the fundamental properties and mechanism of the flexible sensors such as a strain sensor, a temperature sensor, an ultraviolet sensor, a tactile pressure sensor, and a chemical sensor, integrated device applications with several sensors on a flexible film are demonstrated as proof-of-concepts for multi-functional e-skins. Although a lot of researches and developments are still required for practical application, these studies may help to open a door for the next step of flexible electronics.

Fully inkjet-printed multilayered graphene-based flexible electrodes for repeatable electrochemical response.

Graphene has proven to be useful in biosensing applications. However, one of the main hurdles with printed graphene-based electrodes is achieving repeatable electrochemical performance from one printed electrode to another. We have developed a consistent fabrication process to control the sheet resistance of inkjet-printed graphene electrodes, thereby accomplishing repeatable electrochemical performance. Herein, we investigated the electrochemical properties of multilayered graphene (MLG) electrodes fully inkjet-printed (IJP) on flexible Kapton substrates. The electrodes were fabricated by inkjet printing three materials – (1) a conductive silver ink for electrical contact, (2) an insulating dielectric ink, and (3) MLG ink as the sensing material. The selected materials and fabrication methods provided great control over the ink rheology and material deposition, which enabled stable and repeatable electrochemical response: bending tests revealed the electrochemical behavior of these sensors remained consistent over 1000 bend cycles. Due to the abundance of structural defects (e.g., edge defects) present in the exfoliated graphene platelets, cyclic voltammetry (CV) of the graphene electrodes showed good electron transfer (k = 1.125 × 10−2 cm s−1) with a detection limit (0.01 mM) for the ferric/ferrocyanide redox couple, [Fe(CN)6]−3/−4, which is comparable or superior to modified graphene or graphene oxide-based sensors. Additionally, the potentiometric response of the electrodes displayed good sensitivity over the pH range of 4–10. Moreover, a fully IJP three-electrode device (MLG, platinum, and Ag/AgCl) also showed quasi-reversibility compared to a single IJP MLG electrode device. These findings demonstrate significant promise for scalable fabrication of a flexible, low cost, and fully-IJP wearable sensor system needed for space, military, and commercial biosensing applications.

(Invited) Multi-Functional Flexible Physical and Chemical Sensor Sheets

Mechanically flexible and stretchable devices have been attracted much attention for a next class of electronics such as flexible photovoltaics, flexible displays, and wearable electronics. In particular, multiple sensors for potential applications such as wearable healthcare devices and Internet of Things (IoT) concepts are one of the most important components for moving forward to building the flexible sensor system platform. For healthcare application, chemical information such as pH, glucose, sodium ion, and pattaisum ion levles are very important to monitor as well as physical information such as activity, skin temperature, heartbeat, and electrocardiogram (ECG) signals. Furthermore, simultaneous multiple condition monitoring including physical and chemical information is a next class of wearable devices for convienient and safe human life. To address these challenges, in this talk, flexible physical and chemical sensor sheets using mainly inorganic nanomaterials will be introduced by proposing low-cost, macroscale, and multi-functional device integrations. Especially human-interactive flexible sensors to detect human motion, health condition, and room environment information are mainly discussed. In addition to the fundamental sensor characteristics of a strain sensor, a temperature sensor, an ultraviolet sensor, a tactile pressure sensor, and a chemical sensor, integrated device applications with several sensors on a flexible film are demonstrated as proof-of-concepts for multi-functional flexible healthcare sensor sheets. Although a lot of investigations and developments are still required for practical application as products, these studies may help to open a door for the next step of flexible electronics.

Analysis and monitoring of IoT-assisted human physiological galvanic skin responsefactor for smart e-healthcare

PurposeBackground: Every so often, one experiences different physically unstable situations which may lead to possibilities of suffering through vicious physiological risks and extents. Dynamic physiological activities are such a key metric that they are perceived by means of measuring galvanic skin response (GSR). GSR represents impedance of human skin that frequently changes based on different human respiratory and physical instability. Existing solutions, paved in literature and market, focus on the direct measurement of GSR by two sensor-attached leads, which are then parameterized against the standard printed circuit board mechanism. This process is sometimes cumbersome to use, resulting in lower user experience provisioning and adaptability in livelihood activities. The purpose of this study is to validate the novel development of the cost-effective GSR sensing system for affective usage for smart e-healthcare.Design/methodology/approachThis paper proposes to design and develop a flexible circuit strip, populated with essential circuitry assemblies, to assess and monitor the level of GSR. Ordinarily, this flexible system would be worn on the back palm of the hand where two leads would contact two sensor strips worn on the first finger.FindingsThe system was developed on top of Pyralux. Initial goals of this work are to design and validate a flexible film-based GSR system to detect an individual’s level of human physiological activities by acquiring, amplifying and processing GSR data. The measured GSR value is visualized “24 × 7” on a Bluetooth-enabled smartphone via a pre-incorporated application. Conclusion: The proposed sensor-system is capable of raising the qualities such as adaptability, user experience, portability and ubiquity for possible application of monitoring of human psychodynamics in a more cost-effective way, i.e. less than US$50.Practical implicationsSeveral novel attributes are envisaged in the development process of the GSR system that made it different from and unique as compared to the existing alternatives. The attributes are as follows: (i) use of reproductive sensor-system fabrication process, (ii) use of flexible-substrate for hosting the system as proof of concept, (iii) use of miniaturized microcontroller, i.e. ATTiny85, (iv) deployment of energy-efficient passive electrical circuitry for noise filtering, (v) possible use case scenario of using CR2032 coin battery for provisioning powering up the system, (vi) provision of incorporation of internet of things (IoT)-cloud integration in existing version while fixing related APIs and (vii) incorporation of heterogeneous software-based solutions to validate and monitor the GSR output such as MakerPlot, Arduino IDE, Fritzing and MIT App Inventor 2.Originality/valueThis paper is a revised version R1 of the earlier reviewed paper. The proposed paper provides novel knowledge about the flexible sensor system development for GSR monitoring under IoT-based environment for smart e-healthcare.