Ionic hydrogels, a class of intrinsically stretchable and conductive materials, are widely used in soft electronics. However, the easy freezing and drying of water-based hydrogels significantly limit their long-term stability. Here, a facile solvent-replacement strategy is developed to fabricate ethylene glycol (Eg)/glycerol (Gl)-water binary antifreezing and antidrying organohydrogels for ultrastretchable and sensitive strain sensing within a wide temperature range. Because of the ready formation of strong hydrogen bonds between Eg/Gl and water molecules, the organohydrogels gain exceptional freezing and drying tolerance with retained deformability, conductivity, and self-healing ability even stay at extreme temperature for a long time. Thus, the fabricated strain sensor displays a gauge factor of 6, which is much higher than previously reported values for hydrogel-based strain sensors. Furthermore, the strain sensor exhibits a relatively wide strain range (0.5−950%) even at −18 °C. Various human motions with different strain levels are monitored by the strain sensor with good stability and repeatability from −18 to 25 °C. The organohydrogels maintained the strain sensing capability when exposed to ambient air for nine months. This work provides new insight into the fabrication of stable, ultrastretchable, and ultrasensitive strain sensors using chemically modified organohydrogel for emerging wearable electronics.

An ultrastretchable thermistor that combines intrinsic stretchability, thermal sensitivity, transparency, and self-healing capability is fabricated. It is found the polyacrylamide/carrageenan double network (DN) hydrogel is highly sensitive to temperature and therefore can be exploited as a novel channel material for a thermistor. This thermistor can be stretched from 0 to 330% strain with the sensitivity as high as 2.6%/°C at extreme 200% strain. Noticeably, the mechanical, electrical, and thermal sensing properties of the DN hydrogel can be self-healed, analogous to the self-healing capability of human skin. The large mechanical deformations, such as flexion and twist with large angles, do not affect the thermal sensitivity. Good flexibility enables the thermistor to be attached on nonplanar curvilinear surfaces for practical temperature detection. Remarkably, the thermal sensitivity can be improved by introducing mechanical strain, making the sensitivity programmable. This thermistor with tunable sensitivity is advantageous over traditional rigid thermistors that lack flexibility in adjusting their sensitivity. In addition to superior sensitivity and stretchability compared with traditional thermistors, this DN hydrogel-based thermistor provides additional advantages of good transparency and self-healing ability, enabling it to be potentially integrated in soft robots to grasp real world information for guiding their actions.

Fabrication of stretchable chemical sensors becomes increasingly attractive for emerging wearable applications in environmental monitoring and health care. Here, for the first time, chemically derived ionic conductive polyacrylamide/carrageenan double-network (DN) hydrogels are exploited to fabricate ultrastretchable and transparent NO 2 and NH 3 sensors with high sensitivity (78.5 ppm −1 ) and low theoretical limit of detection (1.2 ppb) in NO 2 detection. The hydrogels can withstand various rigorous mechanical deformations, including up to 1200% strain, large-range flexion, and twist. The drastic mechanical deformations do not degrade the gas-sensing performance. A facile solvent replacement strategy is devised to partially replace water with glycerol (Gly) molecules in the solvent of hydrogel, generating the water−Gly binary hydrogel with 1.68 times boosted sensitivity to NO 2 and significantly enhanced stability. The DN-Gly NO 2 sensor can maintain its sensitivity for as long as 9 months. The high sensitivity is attributed to the abundant oxygenated functional groups in the well-designed polymer chains and solvent. A gas-blocking mechanism is proposed to understand the positive resistance shift of the gas sensors. This work sheds light on utilizing ionic conductive hydrogels as novel channel materials to design highly deformable and sensitive gas sensors.

BackgroundHidden blood loss is a major concern for patients undergoing hip surgery for intertrochanteric fracture. The objective of this study was to investigate whether tranexamic acid (TXA) could reduce postoperative hidden blood loss in patients undergoing hip surgery for intertrochanteric fracture.MethodsA total of 77 patients with intertrochanteric fracture were enrolled in this randomized controlled study. Patients received either 200 mL (1 g) of TXA (n = 37) or normal-saline (NS) (n = 40) i.v. before hip surgery using proximal femoral nail anti-rotation (PFNA). Hemoglobin and hematocrit levels were measured preoperatively and postoperatively at day 1 and 3. Visible and hidden blood loss volumes were calculated at postoperative day 3.ResultsOn postoperative day 3, the transfusion rate was significantly lower in the TXA group compared to the NS group, although mean hemoglobin and hematocrit levels were not significantly different between the two groups. However, the estimated hidden blood loss volume (210.09 ± 202.14 mL vs. 359.35 ± 290.12 mL; P < 0.05) and total blood loss volume (279.35 ± 209.11 mL vs. 417.89 ± 289.56 mL; P < 0.05) were significantly less in the TXA group compared to the NS group, respectively.ConclusionTXA significantly reduced postoperative hidden blood loss in patients with intertrochanteric fracture who underwent PFNA.(Registration number: ChiCTR-INR-16008134).

Stretchable strain sensors have promising applications in health monitoring and human motion detection. However, only a few of the strain sensors reported to date have exhibited a multiscale strain range and a high gauge factor simultaneously. As such, most strain sensors cannot be used in applications that require both high sensitivity and a multiscale strain range. In this work, we develop a wearable multifunctional strain sensor using graphene and a new ionic conductor as the sensing material and Ecoflex as the encapsulant. In the ionic conductor, KCl and glycerol are used as the electrolyte and solvent, respectively. This deformable ionic conductor connects cracked graphene sheets electronically, enabling the strain sensor to be stretched to 300% of its original length with a moderate gauge factor of 25.2. The sensor can respond to various mechanical deformations including stretching, bending, and pressing. When attached to human body, the sensor can monitor large-scale strains (>50%) for joint movement and small-scale strains (<10%) for facial expressions and pulses. When stretched, the sensor also shows good sensitivity in static temperature sensing. Therefore, this multifunctional stretchable sensor has good prospect of applications in human motion detection and health monitoring.

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Background:Patients with dementia might have higher risk for hemorrhagic complications with anticoagulant therapy prescribed for atrial fibrillation (AF).Objective:This study assesses the risks and benefits of warfarin, antiplatelets, and no treatment in patients with dementia and AF.Methods:Of 49,792 patients registered in the Swedish Dementia Registry 2007–2014, 8,096 (16%) had a previous diagnosis of AF. Cox proportional hazards models were used to calculate the risk for ischemic stroke (IS), nontraumatic intracranial hemorrhage, any-cause hemorrhage, and death.Results:Out of the 8,096 dementia patients with AF, 2,143 (26%) received warfarin treatment, 2,975 (37%) antiplatelet treatment, and 2,978 (37%) had no antithrombotic treatment at the time of dementia diagnosis. Patients on warfarin had fewer IS than those without treatment (5.2% versus 8.7%; p < 0.001) with no differences compared to antiplatelets. In adjusted analyses, warfarin was associated with a lower risk for IS (HR 0.76, CI 0.59–0.98), while antiplatelets were associated with increased risk (HR 1.25, CI 1.01–1.54) compared to no treatment. For any-cause hemorrhage, there was a higher risk with warfarin (HR 1.28, CI 1.03–1.59) compared to antiplatelets. Warfarin and antiplatelets were associated with a lower risk for death compared to no treatment.Conclusions:Warfarin treatment in Swedish patients with dementia is associated with lower risk of IS and mortality, and a small increase in any-cause hemorrhage. This study supports the use of warfarin in appropriate cases in patients with dementia. The low percentage of patients on warfarin treatment indicates that further gains in stroke prevention are possible.

Nanomaterials with low-dimensional morphology have been explored for enhancing the performance of strain sensors, but it remains difficult to achieve high stretchability and sensitivity simultaneously. In this work, a composite structure strain sensor based on nanomaterials and conductive liquid is designed, demonstrated, and engineered. The nanowire-microfluidic hybrid (NMH) strain sensor responds to multiscale strains from 4% to over 400%, with a high sensitivity and durability under small strain. Metal nanowires and carbon nanotubes are used to fabricate the NMH strain sensors, which simultaneously exhibit record-high average gauge factors and stretchability, far better than the conventional nanowire devices. Quantitative modeling of the electrical characteristics reveals that the effective conductivity percolation through the hybrid structures is the key to achieving high gauge factors for multiscale sensing. The sensors can operate at low voltages and are capable of responding to various mechanical deformations. When fixed on human skin, the sensors can monitor large-scale deformations (skeleton motion) and small-scale deformations (facial expressions and pulses). The sensors are also employed in multichannel, interactive electronic system for wireless control of robotics. Such demonstrations indicate the potential of the sensors as wearable detectors for human motion or as bionic ligaments in soft robotics.