Skin Humidity Research Articles

Gas‐Permeable Highly Sensitive Nanomesh Humidity Sensor for Continuous Measurement of Skin Humidity

AbstractOn‐skin humidity sensors can be used to measure the sweat rate on the human skin surface. However, it is challenging to realize a precise, long‐term skin humidity measurement. The main challenge is to develop an on‐skin humidity sensor that has gas permeability, high sensitivity, and flexibility simultaneously. Porous materials and electrodes can enhance the properties of the humidity sensor for fulfilling continuous monitoring. Herein, a humidity sensor composed of nanomesh Au electrodes and nanomesh humidity‐sensitive materials, is reported. The porous structure makes the sensor flexible and gas permeable, increases the surface area, and leads to high sensitivity. The sensor has a high sensitivity of 640 000% in the relative‐humidity range of over 40–100%, together with a gas permeability similar to that of an open environment. The gas permeability suppresses the skin inflammation, endows natural evaporation of sweat, and brings an identical condition with bare skin. To evaluate the utility of the nanomesh sensor, on‐skin humidity measurements are performed, and the humidity change due to sweating after exercise is recorded.

(Invited, Digital Presentation) Heterogeneously Integrated Nanomaterial-Based Multimodal Flexible Sensor Sheets

Human interaction is of great interests for a next class of human society to realize convenient, comfortable, and safe life. For this purpose, multimodal sensing is one of the most important functionalities. Furthermore, without sacrificing the original shape change or uncomfortability to attach or wear the sensor systems onto the targeted surface, respectively, ultrathin and mechanically flexible sensor is required. To address these requirements together, one potential material system is inorganic nanomaterials, which allows it to achieve a variety of material integrated formation on a film and mechanical flexibility due to ultra-small dimensions with high performance. However, the challenges to utilize the nanomaterials for the practical flexible device applications are still remained such as scalability, long-time stability, and multi-functional integrations. In my group, we are trying to develop the heterogeneously integrated nanomaterial-based sensors on flexible films to overcome all challenges to move forward to building the new sensor platforms.In this talk, as the progress on our research activity to contribute the flexible sensor community and IoT applications, multimodal flexible sensors using mainly nanomaterials formed by solution-based and laser-induced methods are discussed for wearable healthcare/medical applications. In addition to the flexible sensors, wireless system and signal processing for the feedback alarm function when the abnormal signal is detected are introduced as the potential flexible sensor application. In particular, electrocardiogram (ECG), skin temperature, and skin humidity flexible sensors and their integration on a flexible film are explained by using fundamental characteristics.This study focuses on the heterogeneously integrated multimodal flexible sensors for the application of remote healthcare applications. Although additional functional sensors and systems to realize more useful and convenient home-use healthcare system is required, the approaches may contribute the further developments to open a next class of electronics for IoT.

Antimicrobial second skin using copper nanomesh

The functional support and advancement of our body while preserving inherent naturalness is one of the ultimate goals of bioengineering. Skin protection against infectious pathogens is an application that requires common and long-term wear without discomfort or distortion of the skin functions. However, no antimicrobial method has been introduced to prevent cross-infection while preserving intrinsic skin conditions. Here, we propose an antimicrobial skin protection platform copper nanomesh, which prevents cross-infectionmorphology, temperature change rate, and skin humidity. Copper nanomesh exhibited an inactivation rate of 99.99% for Escherichia coli bacteria and influenza virus A within 1 and 10 min, respectively. The thin and porous nanomesh allows for conformal coating on the fingertips, without significant interference with the rate of skin temperature change and humidity. Efficient cross-infection prevention and thermal transfer of copper nanomesh were demonstrated using direct on-hand experiments.

Construction and Performance of a Nanocellulose–Graphene-Based Humidity Sensor with a Fast Response and Excellent Stability

Humidity sensors have been widely applied in environmental monitoring, respiratory monitoring, electronic skin, noncontact switch, etc. However, weak interface interactions between a flexible substrate and conductive fillers will deteriorate the sensing performance. Herein, a flexible, rapid-response, and durable humidity sensor was proposed via employing cellulose nanofiber (CNF)-dispersed graphene (Gr) as a humidity sensing layer, which could be easily filtered onto a coessential CNF film (CNFF) to form the humidity sensor. CNFs as a dispersant and bonder strengthened the adhesion of graphene on the surface of the CNFF substrate. Simultaneously, CNFs as a reservoir provided abundant adsorption sites to capture water molecules and promoted electron transfer from adsorbed water molecules to graphene, further amplifying electrical signals by a hygroscopic expansion of the sensing layer under humidity conditions. Benefiting from this unique composition and structure, the prepared humidity sensor exhibited a rapid response (45 s) and recovery time (33 s), low hysteresis (4%), wide RH detection range (15–99%), and long-term stability (15 days). Further, the sensor could monitor the humidity of human skin and human breath, indicating a versatile noncontact humidity sensing function by altering its component proportion of CNF-to-Gr on demand.

Flexible highly-sensitive humidity sensor based on CGO/SMPLAF for wearable human skin humidity detection

Conventional humidity sensors have poor flexibility and low sensitivity, which makes them difficult for wearable electronic device applications. This study aims to fabricate a flexible, high-sensitivity and breathable humidity sensor for skin humidity monitoring. The sensor includes two parts, i.e., shape memory polylactic acid fiber (SMPLAF) as the substrate and crumpled graphene oxide (CGO) membrane as the top humidity-sensitive layer. SMPLAF was firstly stretched and then heated to restore its original shape to obtain the CGO membrane. The unique crumpled morphology of CGO membrane provides a large specific surface area and high capillary force, which facilitates the rapid exchange of water molecules between the sensing CGO membrane and the external environment. Accordingly, the sensor exhibits excellent humidity sensitivity, fast response time (<5 s) and long term stability (15 days). Moreover, the CGO-based sensor demonstrates excellent flexibility. Bent at 120°, the response almost unchanged, whereas the response of the sensor without CGO decreased from 0.89 to 0.66. Though the sensor has the disadvantage of unstable performance at high RH, it could be overcome by controlling the wavelength of the crumpled structure of CGO. Due to the above superior properties, the sensor shows promising potentials for human breath monitoring and skin humidity test.

Highly Sensitive and Stable Humidity Sensor Based on the Bi-Layered PVA/Graphene Flower Composite Film.

Two-dimensional (2D) materials and their composites have gained significant importance as the functional layer of various environmental sensors and nanoelectronics owing to their unique properties. This work reports for the first time a highly sensitive, fast, and stable humidity sensor based on the bi-layered active sensing area composed of graphene flower (GF) and poly (vinyl alcohol) PVA thin films for multifunctional applications. The GF/PVA humidity sensor exhibited stable impedance response over 15 days, for a relative humidity (RH) range of (40–90% RH) under ambient operating conditions. The proposed bi-layered humidity sensor also exhibited an ultra-high capacitive sensitivity response of the 29 nF/%RH at 10 kHz and fast transient response of 2 s and 3.5 s, respectively. Furthermore, the reported sensor also showed a good response towards multi-functional applications such as non-contact skin humidity and mouth breathing detection.

Optical Microfibers for Sensing Proximity and Contact in Human-Machine Interfaces.

The monitoring of proximity-contact events is essential for human-machine interactions, intelligent robots, and healthcare monitoring. We report a dual-modal sensor made with two functionalized optical microfibers (MFs), which is inspired by the somatosensory system of human skin. The integrated sensor with a hierarchical structure gradationally detects finger approaching and touching by measuring the relative humidity (RH) and force-triggered light intensity variations. Specifically, the RH sensory part shows enhanced evanescent absorption, achieving a sensitive RH measurement with a fast response (110 ms), a high resolution (0.11%RH), and a wide working range (10-100%RH). Enabled by the transition from guided modes into radiation modes of the waveguiding MF, the force sensory part exhibits a high sensitivity (6.2%/kPa) and a fast response (up to 1.5 kHz). By using a real-time data processing unit, the proximity-contact sensor (PCS) achieves continuous detection of the full-contact events, including finger approaching, contacting, pressing, releasing, and leaving. As a proof of concept, the electromagnetic-interference-free PCS enables a smart switch system to recognize the proximity and contact of bare/gloved fingers. Moreover, skin humidity detection and respiration monitoring are realized. These initial results pave the way toward a category of optical collaborative devices ranging from human-machine interfaces to multifunctional on-skin healthcare sensors.

High performance humidity sensor based on 3D mesoporous Co3O4 hollow polyhedron for multifunctional applications

In this work, the three-dimensional (3D) hollow mesoporous Co3O4 was successfully prepared by calcining the Co-based zeolitic imidazolate framework-67 (ZIF-67). As-obtained Co3O4 inherited the rhombohedral framework structure of ZIF-67 and possessed mesoporous and hollow structure. Further, the humidity sensor based on Co3O4 was fabricated, and its humidity sensing properties were investigated at room temperature (25 °C). The results indicated that the Co3O4 humidity sensor exhibited high humidity sensing performance with a wide linear detection range (10%−95% relative humidity (RH)), small humidity hysteresis (2.6% RH), and fast response/recovery times (1.0/13.5 s). In particular, the Co3O4 humidity sensor was of high detection resolution (1% RH). The excellent performance was attributed to the strong hydrophilicity and the unique 3D porous structure of Co3O4. In addition, the potential applications of the fabricated Co3O4 humidity sensor in skin humidity, simulated diaper, human breathing, and non-contact switch were demonstrated. This work provides a promising humidity sensing material for fabricating high-performance humidity sensors.

Two dimensional Zirconium diselenide based humidity sensor for flexible electronics

Transition metal dichalcogenides (TMDCs), a class of two-dimensional (2D) materials with layered structures, have recently gained a lot of attention for highly sensitive humidity sensing applications. Hence, for the first time, it proposes a highly sensitive and fast humidity sensor based on the 2D Zirconium Diselenide (ZrSe2) material with unique humidity sensing performance via printed technologies. The spin coating technique was used to deposit the 2D ZrSe2 flakes onto the inter-digital electrodes (IDEs). Herein, the bulk ZrSe2 powder was exfoliated into the 2D flakes via wet grinding. The proposed sensor shows a high sensitivity of 68 kΩ / %RH (where RH is relative humidity) with a wide detection range of (15–80%) RH having good linearity and stability over 360 min. The sensor showed a transient response of 1 s and 2 s for impedance while 3 s and 6 s for capacitance. Hence, the fabricated sensor can be exhibited an ultra-high sensitivity and quick response in various applications: contactless humidity sensing, water spraying test, and skin humidity test. From these exceptional performances, the proposed sensor can be applied in multiple humidity sensing applications.

Профілактика і лікування пролежнів у відділенні інтенсивної терапії (огляд літератури)

У статті з позиції Міжнародної національної нарадо-рекомендаційної ради з пролежнів, Європейської рекомендаційної ради з пролежнів, Всесвітнього альянсу з проблем пролежнів наведено питання термінології, статистики, факторів ризику розвитку, міжнародної класифікації, основних напрямків профілактики, диференціальної діагностики, інспекції шкірних покривів і документування; наведено шкали для прогнозування ризику розвитку пролежнів (PUSH Toll, 2008); викладені вузлові питання інтенсивної терапії залежно від результатів категорії пролежнів; надано правило SPECIAL; рекомендації робочої групи ICSI. Наведено практичні рекомендації Американської колегії фізіотерапевтів. Особливу увагу приділено принципам нутритивної терапії за наявності пролежнів.

A flexible humidity sensor based on self-supported polymer film

Self-supported polymer films were fabricated by the thiol-ene click cross-linking reaction in this work. The cross-linked frameworks were used to guarantee the stability the films. The hydrophilic monomer with different contents were introduced into the self-supported thick films and uniformly dispersed in the polymer frameworks. The interdigitated electrodes were screen printed with silver paste on the self-supported films to obtain humidity sensors. Herein, the self-supported film acts as both the sensor substrate and the humidity-sensing material. The humidity sensing performances of the obtained sensors were systematically researched. By optimizing the ratio of hydrophilic monomer in the polymer films, the sensitivities of the sensors were enhanced from 1.58 to 103.75 (in the humidity from 11% RH to 95% RH), the response under low RH environment was significantly improved with good linearity. The response/recovery times of the sensor within the humidity range are measured to be 12.5 s and hundreds of seconds. The prepared flexible sensors possess certain mechanical properties, and exhibit good stability under bending and long-term tests up to 60 days. The applications of the as-prepared sensor in the detection of non-contact human skin humidity, human respiration and relative humidity of green plant were explored. The sensor shows excellent sensing performance in various applications and indicates the potential application in wearable and multifunctional devices.

Оценка эффективности лечения мелазмы по биофизическим показателям кожи

This article presents an assessment of the effectiveness of treatment of melasma according to the biophysical indicators of skin 176 patients who applied to the DIVA EFFECT private cosmetology clinic in Bishkek (Kyrgyzstan) in 2018–2020. The control group included 85 women without facial skin pigmentation. Criteria for inclusion in the study of patients: age 20–60 years, skin pigmentation for 1–12 years, residence in Kyrgyzstan, informed consent and consent to procedures for diagnosis, treatment. Amounts of sebum on skin surface, level of skin moisture and pigmentation, acid-alkaline balance of skin are determined. Despite the lack of sebum in all types of melasma, greater fat content was detected at 20–29 years old, including in the control group. The treatment helped to increase skin humidity, but with different intensities. Treatment slightly increased skin humidity, but only dry skin was characteristic of patients, both in the experimental and control groups. In patients of the control group, skin pH was from 4.1±0.5 to 4.8±0.5. The acid-alkaline balance of the skin in patients was mainly lower than normal, with the exception of the age group of 20–29 years, 30–39 years with dermal melasma. After treatment, the melanin content was within normal range at all types of melasma compared to the control group. The treatment performed reduced skin greasiness in epidermal and dermal type, acid-alkaline skin balance in dermal and mixed type. Melanin levels decreased and skin humidity increased slightly with all types.

Nanoporous naphthalene diimide surface enhances humidity and ammonia sensing at room temperature

We report fabrication and characterisation of humidity and ammonia sensors based on a nanoporous naphthalene diimide (NDI) thin layer, the active material coded as NDI-1, operating at room temperature. A thin layer of NDI-1 as an organic semiconducting sensing material was deposited onto the interdigitated electrodes using the spin-coating technique. Surface morphology investigations of the thin film using atomic force microscopy and scanning electronic microscopy revealed a uniform nanoporous surface. Structural and thermal behaviour studies of the NDI-1 using X-ray diffraction and thermogravimetric analyses confirmed the crystallinity and thermal stability, respectively. The capacitive type NDI-1 humidity sensor displayed a sensitivity of 10.13 pF/%RH, quick response and recovery (20.1/6.28 s), low hysteresis (0.72%), long-term stability and more importantly, a wide working range of relative humidity (10–95%) at 250 Hz. Interestingly, the developed sensor was sensitive enough to monitor respiration rate and demonstrated an excellent non-contact skin humidity sensing performance. The amperometric response of the sensor towards ammonia was also investigated. An increase in the sensor current was recorded when exposed to different ammonia concentrations (25, 37.5 and 50 ppm). The sensor showed high selectivity and good sensitivity (27.7%) towards 50 ppm ammonia with 200 s and 350 s response and recovery times, respectively.

Flexible, non-contact and multifunctional humidity sensors based on two-dimensional phytic acid doped co-metal organic frameworks nanosheets

The development of high-performance humidity sensors is of great significance to explore their practical applications in the fields of environment, energy saving and safety monitoring. Herein, a flexible, non-contact and multifunctional humidity sensor based on two-dimensional Co-metal organic frameworks (Co-MOF) nanosheets is proposed, which is fabricated by simple bottom-up synthesis method. Furthermore, environmentally friendly, renewable and abundant biomass phytic acid (PA) is modified on the surface of Co-MOF nanosheets, which releases free protons being capable of etching the framework of MOF to improve the hydrophilicity and conductivity of MOF. Compared with Co-MOF-based sensor, the Co-MOF@PA-based sensor exhibits significantly enhanced sensitivity and broadened response range within 23–95% relative humidity (RH). The humidity sensor has an excellent humidity sensing response over 2 × 103. The Co-MOF@PA-based sensor shows good flexibility and humidity sensing properties, endowing it with multifunctional applications in real-time facial respiration monitoring, skin humidity perception, cosmetic moisturizing evaluation and fruit freshness testing. Four respiration patterns, including slow breath, deep breath, normal breath and fast breath are wirelessly monitored in real time by Co-MOF@PA-based sensor and recorded by mobile phone software. The research work presents potential applications in human–machine interactions (HMI) devices in future.

Skin-electrode iontronic interface for mechanosensing

Electrodermal devices that capture the physiological response of skin are crucial for monitoring vital signals, but they often require convoluted layered designs with either electronic or ionic active materials relying on complicated synthesis procedures, encapsulation, and packaging techniques. Here, we report that the ionic transport in living systems can provide a simple mode of iontronic sensing and bypass the need of artificial ionic materials. A simple skin-electrode mechanosensing structure (SEMS) is constructed, exhibiting high pressure-resolution and spatial-resolution, being capable of feeling touch and detecting weak physiological signals such as fingertip pulse under different skin humidity. Our mechanical analysis reveals the critical role of instability in high-aspect-ratio microstructures on sensing. We further demonstrate pressure mapping with millimeter-spatial-resolution using a fully textile SEMS-based glove. The simplicity and reliability of SEMS hold great promise of diverse healthcare applications, such as pulse detection and recovering the sensory capability in patients with tactile dysfunction.

Flexible humidity sensor based on modified cellulose paper

Abstract It is of great significance to exploit a simple, cost-effective and environmentally friendly preparation method of multifunctional humidity sensors. However, most humidity sensors need complex manufacturing processes, high cost and narrow usage range. Herein, humidity sensors based on glycidyl trimethyl ammonium chloride (EPTAC) modified cellulose paper via a facile solution method were fabricated, among which the paper is used for the purpose of the humidity sensing material and the sensor substrate. The sensitivity of the obtained sensor was improved by the modification of EPTAC, the response time was decreased to 25 s, which is equivalent to the first-rate paper-based humidity sensors. In addition, the paper-based humidity sensor is provided with well flexibility and biocompatibility, and it exhibits multifunctional applications in respiratory monitoring, non-contact switch and skin humidity monitoring. The low cost and facile preparation technique in this work could provide a useful strategy for developing multifunctional humidity sensor.

All range highly linear and sensitive humidity sensor based on 2D material TiSi2 for real-time monitoring

Nowadays, two-dimensional (2D) materials with layered structures, known as transition metal dichalcogenides (TMDCs), are highly appealing in humidity sensing applications. Herein, the humidity sensor based on the 2D material titanium disillicide (TiSi2) is exploited for the first time with high sensing performances for the continuous monitoring of various human interactive activities such as breath monitoring and contactless skin humidity sensing. It proposes a highly sensitive humidity sensor with excellent all range linear humidity sensing performance through printed technologies. Inter-digital electrodes (IDEs) are fabricated through a screen printing process, and the 2D TiSi2 the active layer is coated on the electrodes through the spin-coating process. Furthermore, the TiSi2 ink is prepared through a wet grinding process to achieve the 2D nano-flakes. The proposed sensor has a decent linear response over an ultra-wide detection range of (0 %–100 %) RH with a fast transient response of 0.9 s and 8 s for impedance while 3 s and 4 s for capacitance. The sensor shows high impedance sensitivity of 63 kΩ / %RH at 1 kHz, having good stability for 360 min. Hence, the fabricated sensor also showed fast response and sensitivity towards various real-time applications such as water spraying test, and real time monitoring. These outstanding performances of the proposed sensor can open new horizons for the variety of humidity sensing applications.

Ultrafast-response/recovery capacitive humidity sensor based on arc-shaped hollow structure with nanocone arrays for human physiological signals monitoring

Abstract Flexible humidity sensors have attracted substantial attention due to the promising application in medical health monitoring. Up to now, the realization of such devices with ultrafast response/recovery and controllable morphology via a facile and cost-effective approach still remains a severe challenge. Herein, a high-performance flexible capacitive humidity sensor by creating the arc-shaped hollow structure with the poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)] nanocone arrays is developed. Particularly, a facile method based on combining the hot-pressing method and the anodized aluminum oxide template transfer method is proposed to realize the large-scale preparation of the nanostructure arrays with controllable morphology. Benefiting from the open arc-shaped hollow structure and the large-area P(VDF-TrFE) nanocone arrays, the proposed humidity sensor shows several conspicuous features, such as ultrafast response/recovery time (3.693/3.430 s), long-term stability (25 days), excellent bending stability (10,000 cycles), unaffected capacitance response to humidity in a certain temperature range (20−50℃) and high selectivity toward water vapor. The above salient superiorities enable the proposed humidity sensor to be successfully utilized in extraction of a variety of physiological signals including breathing detection, skin noncontact sensing, and real-time monitoring of diaper wetting process and skin humidity, which reveals great potential value in prevention and diagnosis of many diseases.

Formulation and activity test of extract seaweed lip balm (sargassum binderi) and oil kenanga ( cananga oil ) as lip moisturizer

Cosmetics are preparations or combination of ingredients that ready to be used on the outside of body such as epidermis, hair, nails, lips, teeth and oral cavity. It has a function to clean, increase the attractiveness, change the appearance and protect it to keep the condition in a good state, improve body odor but not intended to cure a disease. The extraction method used to obtain seaweed extract is the maceration method using 96% ethanol solvent. The test method for hydration test uses TEWL within the Derma lab combo tool. Meanwhile, the hedonic test used 20 panelists to determine the level of suitability in lip balm preparations. This Research is about formulation and activity test of seaweed extract (Sargassum binderi) and sunflower oil kenaga (Cananga oil) as lip moisturizer. The purpose of this study was to utilize natural ingredients and determine the evaluation of lipbalm from seaweed and cananga flower oil which has a function to increase the moisture level of lip. The formulation of lipbalm was made by three concentrations, formulation 1, formulation 2 and formulation 3. Evaluation was done to test the skin irritation, skin hydration and hedonic test. The method of skin hydration helps to enhancer and moisture the skin by TEWL (transepodermal water loss) tool of derma lab combo. The result of this research showed that all the formulas does not irritate the skin, moisturize and preferred by the panelists. In the third formula, it has a result to increase the humidity of skin within the high significant differences among the three formulas.

Multifunctional and Ultrasensitive-Reduced Graphene Oxide and Pen Ink/Polyvinyl Alcohol-Decorated Modal/Spandex Fabric for High-Performance Wearable Sensors.

Sensitive and flexible sensors capable of monitoring physiological signals of human body for healthcare have been developed in recent years. It is still a challenge to fabricate a wearable sensor-integrated multifunctional performances and a good fit to human body. Here, an rGO and pen ink/PVA-layered strain-humidity sensor based on MS fabric is prepared through a cost-effective and scalable solution process. The conductive fabric as a strain sensor has a workable strain range (∼300%), ultrahigh sensitivity (maximum gauge factor of 492.8), great comfort, and long-term stability. Notably, a step increase in relative resistance variation will be achieved by controlling the coverage of an ink layer. Moreover, the reliable linear humidity-dependent resistance void of hysteresis and excellent repeatability renders conductive fabrics an opportunity as humidity sensors. Based on these superior multifunctions, the resultant conductive fabric can be applied to detect both human motions and skin humidity, showing potential in applications of wearable electronics for professional athletes.