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2.
Nat Commun ; 12(1): 5008, 2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34429436

RESUMO

Capabilities for continuous monitoring of pressures and temperatures at critical skin interfaces can help to guide care strategies that minimize the potential for pressure injuries in hospitalized patients or in individuals confined to the bed. This paper introduces a soft, skin-mountable class of sensor system for this purpose. The design includes a pressure-responsive element based on membrane deflection and a battery-free, wireless mode of operation capable of multi-site measurements at strategic locations across the body. Such devices yield continuous, simultaneous readings of pressure and temperature in a sequential readout scheme from a pair of primary antennas mounted under the bedding and connected to a wireless reader and a multiplexer located at the bedside. Experimental evaluation of the sensor and the complete system includes benchtop measurements and numerical simulations of the key features. Clinical trials involving two hemiplegic patients and a tetraplegic patient demonstrate the feasibility, functionality and long-term stability of this technology in operating hospital settings.


Assuntos
Técnicas Biossensoriais/métodos , Fontes de Energia Elétrica , Pressão , Temperatura , Tecnologia sem Fio , Adulto , Idoso , Idoso de 80 Anos ou mais , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Pele , Termografia/instrumentação , Termografia/métodos
3.
Adv Healthc Mater ; 10(9): e2001461, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33694309

RESUMO

Conventional flexible pressure sensors are not suitable for high-pressure applications due to their low saturation pressure. In this study, an ultra-wide range pressure sensor is designed based on the optimized microstructure of the polyimide/carbon nanotubes (PI/CNT) nanocomposite film. The sensing range of the pressure sensor is expanded by adopting polyimide (PI) with a high elastic modulus as a matrix material and its sensitivity is improved through functional sensing film with tip-flattened microdome arrays. As a result, the pressure sensor can measure a wide pressure range (≈ 0-3000 kPa) and possesses the sensitivity of ≈ 5.66 × 10-3 -0.23 × 10-3 kPa-1 with high reliability and durability up to 1000 cycles. The proposed sensor is integrated into the hand and foot pressure monitoring systems for workout monitoring. The representative values of the pressure distribution in the hands and feet during the powerlifting are acquired and analyzed through Pearson's correlation coefficient (PCC). The analyzed results suggest that the pressure sensor can provide useful real-time information for healthcare and sports performance monitoring.


Assuntos
Nanocompostos , Nanotubos de Carbono , Dispositivos Eletrônicos Vestíveis , Pressão , Reprodutibilidade dos Testes
4.
Langmuir ; 36(30): 8939-8946, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32610911

RESUMO

Soft strain sensors have attracted significant attention in wearable human motion monitoring applications. However, there is still a huge challenge for decoupled measurement of multidirectional strains. In this study, we have developed a biaxial and stretchable strain sensor based on a carbon nanotube (CNT) film and a microdome array (MA)-patterned elastomeric substrate. The MA structures lead to generating localized and directional microcracks of CNT films within the intended regions under tensile strain. This mechanism allows a single sensing layer to act as a strain sensor capable of decoupling the biaxial strains into axial and transverse terms. The ratio of resistance change between two perpendicular axes is about 960% under an x-directional strain of 30%, demonstrating the biaxial decoupling capability. Also, the proposed strain sensor shows high stretchability and excellent long-term reliability under a cyclic loading test. Finally, wearable devices integrated with the strain sensor have been successfully utilized to monitor various human motions of the wrist, elbow, knee, and fingers by measuring joint bending and skin elongation.


Assuntos
Nanotubos de Carbono , Dispositivos Eletrônicos Vestíveis , Humanos , Movimento (Física) , Reprodutibilidade dos Testes
7.
ACS Sens ; 5(2): 481-489, 2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-32020796

RESUMO

In this research, an ultrathin, biocompatible, and flexible pressure sensor with a wide pressure range has been developed and applied in biomedical applications. The pressure sensing mechanism is based on the variation of contact resistance between an electrode and a three-dimensional microstructured polyimide/carbon nanotube composite film. The sensor has a thickness of about 31.3 µm, a maximum sensitivity of 41.0 MPa-1, and a sensing range of 10-500 kPa. Moreover, in situ temperature measurement by an integrated resistive temperature detector enables data correction for varying temperature conditions. In order to show the advantages of the fabricated sensor, it is attached to the human body and integrated with the surface of a radiofrequency ablation (RFA) needle with small radius of curvature. In the experiments, the proposed pressure sensor measured subtle pressure levels (pulse pressure) and high pressure levels (fingertip pressure) without losing conformal contact with the skin. In addition, when the pressure-sensor-integrated RFA needle was inserted into a bovine liver, successful detection of steam popping phenomenon was observed.


Assuntos
Técnicas Biossensoriais/métodos , Humanos
8.
ACS Appl Mater Interfaces ; 12(11): 13338-13347, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32073247

RESUMO

Despite various advantages and usefulness of semiconductor metal oxide gas sensors, low selectivity and humidity interference have limited their practical applications. In order to resolve these issues, we propose a new concept of a selective gas filtering structure that increases the gas selectivity and decreases the moisture interference of metal oxide gas sensors by coating metal organic frameworks (MOFs) on a microporous elastomer scaffold. Cu(BTC) with an excellent selective adsorption capacity for carbon monoxide (CO) compared to hydrogen (H2) and MIL-160 with an excellent moisture adsorption capacity were uniformly coated on the microporous polydimethylsiloxane (PDMS) structure through a squeeze coating method, resulting in a high content of MOFs with a large effective surface area. A Cu(BTC)-coated microporous PDMS filter showed an excellent adsorption efficiency (62.4%) for CO, thereby dramatically improving the selectivity of H2/CO by up to 2.6 times. In addition, an MIL-160 coated microporous PDMS filter showed a high moisture adsorption efficiency (76.2%).

9.
ACS Appl Mater Interfaces ; 12(1): 1698-1706, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31825585

RESUMO

Wearable pressure sensors have been attracting great attention for a variety of practical applications, including electronic skin, smart textiles, and healthcare devices. However, it is still challenging to realize wearable pressure sensors with sufficient sensitivity and low hysteresis under small mechanical stimuli. Herein, we introduce simple, cost-effective, and sensitive capacitive pressure sensor based on porous Ecoflex-multiwalled carbon nanotube composite (PEMC) structures, which leads to enhancing the sensitivity (6.42 and 1.72 kPa-1 in a range of 0-2 and 2-10 kPa, respectively) due to a synergetic effect of the porous elastomer and percolation of carbon nanotube fillers. The PEMC structure shows excellent mechanical deformability and compliance for an effective integration with practical wearable devices. Also, the PEMC-based pressure sensor shows not only the long-term stability, low-hysteresis, and fast response under dynamic loading but also the high robustness against temperature and humidity changes. Finally, we demonstrate a prosthetic robot finger integrated with a PEMC-based pressure sensor and an actuator as well as a healthcare wristband capable of continuously monitoring blood pressure and heart rate.


Assuntos
Técnicas Biossensoriais , Determinação da Pressão Arterial/instrumentação , Monitorização Fisiológica , Nanotubos de Carbono/química , Elastômeros/química , Humanos , Fenômenos Mecânicos , Porosidade , Têxteis , Dispositivos Eletrônicos Vestíveis
10.
Adv Healthc Mater ; 8(22): e1900978, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31596545

RESUMO

Wearable pressure sensors capable of sensitive, precise, and continuous measurement of physiological and physical signals have great potential for the monitoring of health status and the early diagnosis of diseases. This work introduces a 3D-printed rigid microbump-integrated liquid metal-based soft pressure sensor (3D-BLiPS) for wearable and health-monitoring applications. Using a 3D-printed master mold based on multimaterial fused deposition modeling, the fabrication of a liquid metal microchannel and the integration of a rigid microbump array above the microchannel are achieved in a one-step, direct process. The microbump array enhances the sensitivity of the pressure sensor (0.158 kPa-1 ) by locally concentrating the deformation of the microchannel with negligible hysteresis and a stable signal response under cyclic loading. The 3D-BLiPS also demonstrates excellent robustness to 10 000 cycles of multidirectional stretching/bending, changes in temperature, and immersion in water. Finally, these characteristics are suitable for a wide range of applications in health monitoring systems, including a wristband for the continuous monitoring of the epidermal pulse rate for cuffless blood pressure estimation and a wireless wearable device for the monitoring of body pressure using a multiple pressure sensor array for the prevention of pressure ulcers.


Assuntos
Impressão Tridimensional , Dispositivos Eletrônicos Vestíveis , Pressão , Temperatura , Tecnologia sem Fio
11.
ACS Appl Mater Interfaces ; 11(26): 23639-23648, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31180635

RESUMO

Flexible and wearable pressure sensors have attracted a tremendous amount of attention due to their wider applications in human interfaces and healthcare monitoring. However, achieving accurate pressure detection and stability against external stimuli (in particular, bending deformation) over a wide range of pressures from tactile to body weight levels is a great challenge. Here, we introduce an ultrawide-range, bending-insensitive, and flexible pressure sensor based on a carbon nanotube (CNT) network-coated thin porous elastomer sponge for use in human interface devices. The integration of the CNT networks into three-dimensional microporous elastomers provides high deformability and a large change in contact between the conductive CNT networks due to the presence of micropores, thereby improving the sensitivity compared with that obtained using CNT-embedded solid elastomers. As electrical pathways are continuously generated up to high compressive strain (∼80%), the pressure sensor shows an ultrawide pressure sensing range (10 Pa to 1.2 MPa) while maintaining favorable sensitivity (0.01-0.02 kPa-1) and linearity ( R2 ∼ 0.98). Also, the pressure sensor exhibits excellent electromechanical stability and insensitivity to bending-induced deformations. Finally, we demonstrate that the pressure sensor can be applied in a flexible piano pad as an entertainment human interface device and a flexible foot insole as a wearable healthcare and gait monitoring device.


Assuntos
Técnicas Biossensoriais , Elastômeros/química , Nanotubos de Carbono/química , Dispositivos Eletrônicos Vestíveis , Elastômeros/uso terapêutico , Condutividade Elétrica , Humanos , Porosidade , Pressão
12.
ACS Appl Mater Interfaces ; 10(15): 12870-12877, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29578325

RESUMO

High-performance and low-power flexible Schottky diode-based hydrogen sensor was developed. The sensor was fabricated by releasing Si nanomembrane (SiNM) and transferring onto a plastic substrate. After the transfer, palladium (Pd) and aluminum (Al) were selectively deposited as a sensing material and an electrode, respectively. The top-down fabrication process of flexible Pd/SiNM diode H2 sensor is facile compared to other existing bottom-up fabricated flexible gas sensors while showing excellent H2 sensitivity (Δ I/ I0 > 700-0.5% H2 concentrations) and fast response time (τ10-90 = 22 s) at room temperature. In addition, selectivity, humidity, and mechanical tests verify that the sensor has excellent reliability and robustness under various environments. The operating power consumption of the sensor is only in the nanowatt range, which indicates its potential applications in low-power portable and wearable electronics.

13.
Sci Rep ; 8(1): 264, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29321531

RESUMO

A biopsy needle with electrical impedance sensor array based on stainless steel microelectrodes (EIS needle) was developed for real-time four electrode measurement and multi-spot sensing of tissues during the biopsy process. The sensor performance was characterized by using saline solutions with various concentrations, which proved accurate, stable and reliable electrical impedance measurement. The capability of impedance-based tissue sensing was verified by the conductivity measurement of agarose hydrogel based phantom mimicking cancer tissue. Furthermore, multi-spot impedance sensing during needle insertion was demonstrated using porcine meat with muscle and fat layers, which exhibited a clear discrimination between different types of tissues. Also, the electrical impedance difference between normal and fatty livers of mouse model was measured by the EIS needle. We could successfully demonstrate that the EIS needle can provide localized and accurate characterization of biological tissues at the needle tip.


Assuntos
Biópsia/métodos , Técnicas Biossensoriais , Impedância Elétrica , Microeletrodos , Agulhas , Animais , Biópsia/instrumentação , Desenho de Equipamento , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Suínos
14.
J Org Chem ; 73(20): 8106-8, 2008 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-18808183

RESUMO

Careful examination of nucleophilicity, basicity, and leaving group ability led us to discover the nucleophilic fluorination of triflates by weakly basic tetrabutylammonium bifluoride, which provides excellent yields with minimal formation of elimination-derived side products. Primary hydroxyl groups as well as secondary hydroxyl groups in acyclic chains or in five-membered rings are excellent substrates, whereas benzylic and aldol-type secondary hydroxyl groups give poor yields as a result of the instability of their triflates.


Assuntos
Compostos de Amônio Quaternário/química , Química Orgânica/métodos , Flúor/química , Halogenação
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