Silicon Strain Research Articles

Design and fabrication of ultrathin silicon-based strain gauges for piezoresistive pressure sensor

Ultra-thin (20 μm) silicon strain gauges were fabricated with silicon-on-insulator (SOI) wafer by a newly-conceived wet etching process. Buffered oxide etchant (BOE, NH4F: HF = 6:1) solution with additives of octylamine and octanol was used for wet etching process in which the operating temperature was 50°C. Photoresist as a passivation layer was deposited on the upper side of SOI wafer to minimize strain gauge damage by chemical etchants. Small amount of octylamine and octanol were added to BOE solution to improve surface wettability and SiO2/Si selectivity. The fabricated strain gauges were attached to the pressure diaphragm and the performance of strain gauge was investigated by measuring with the hydraulic pressure system. The resistance changed linearly with tensile and compressive strains. Maximum values of non-linearity, hysteresis, thermal coefficient of resistance (TCR) and sensitivity were -0.341 %, 0.909 %, 4128 ppm/°C and 34.22 mV/V respectively. The fabricated strain gauges might be well applicable to the hydrogen pressure sensor which is detectable for high pressure range (0–900 bar).

Flexible Superconducting Wiring for Integration with Low-Temperature Detector and Readout Fabrication

We present a method of creating high-density superconducting flexible wiring on flexible thin silicon substrates. The flexible wiring, called SOI flex, is created by depositing superconducting wiring on a silicon-on-insulator (SOI) wafer, selectively etching away the thicker silicon section handle layer, and bending the thinner silicon device layer. We show measurements of superconducting transition temperature and critical current for Mo, Nb, and Al on SOI flex. We discuss the expected advantages of SOI flex for low-temperature detector applications, as well as the role of stress and strain in bent silicon and niobium.

Valley splitting by extended zone effective mass approximation incorporating strain in silicon

Valley splitting by extended zone effective mass approximation incorporating strain in silicon

Substrate-Free Transfer of Silicon- and Metallic-Based Strain Sensors on Textile and in Composite Material for Structural Health Monitoring.

New technologies to integrate electronics and sensors on or into objects can support the growth of embedded electronics. The method proposed in this paper has the huge advantage of being substrate-free and applicable to a wide range of target materials such as fiber-based composites, widely used in manufacturing, and for which monitoring applications such as fatigue, cracks, and deformation detection are crucial. Here, sensors are first fabricated on a donor substrate using standard microelectronic processes and then transferred to the host material by direct transfer printing. Results show the viability of composites instrumented by strain gauges. Indeed, dynamic and static measurements highlight that the deformations can be detected with high sensitivity both on the surface and at various points in the depth of the composite material. Thanks to this technology, for the first time, a substrate-free piezoresistive n-doped silicon strain sensor is transferred into a composite material and characterized as a function of strain applied on it. It is shown that the transfer process does not alter the electrical behavior of the sensors that are five times more sensitive than extensively used metallic ones. An application designed for monitoring the deformation of a rudder foil with a classic NACA profile in real time is presented.

Analysis of Failure Mechanism and Reliability Enhancement of Silicon Strain Gauge-Based Pressure Sensor for Automotive Applications

Hydrogen fuel cell vehicles have gained more attention as future automobiles due to their environmental benefits and extended driving ranges. Concurrently, the global hydrogen sensor market is also experiencing substantial growth. These sensors are integrated into vehicles to detect hydrogen leakage and concentration, thereby ensuring the safety of hydrogen fuel cell vehicles. In particular, hydrogen pressure sensors, commonly installed on the manifold and regulator of vehicles, can measure hydrogen pressure and diagnose safety concerns caused by hydrogen leakage in advance. In this paper, we identify the vulnerable points of hydrogen pressure sensors when exposed to vehicle driving environments, investigate failure mechanisms, and provide process optimization techniques. Specifically, our reliability modeling verifies that the components of a printed circuit board (PCB) exposed to humid environments undergo corrosion due to ion migration, leading to the generation of extrinsic series or parallel resistances, which in turn cause fluctuations of output voltage. Through structural and elemental analysis, we pinpoint process-related factors that make components vulnerable to humidity, thereby suggesting recommendations for enhancing the manufacturing process. Based on this analysis in the development stage, we can proactively address and improve reliability and further safety-related issues for future automobiles, thus preventing real field issues.

Design of flexible sensor for wind pressure monitoring of stay cables

Strong winds can make a bridge’s cable-stayed cables produce violent vibrations, leading to fatigue of the cable-stayed cables and damaging the cable-stayed bridge’s structure. Accurately and effectively obtaining data on the wind loads applied to the cable-stayed cables is important for assessing the cable-stayed cables’ health. The existing sensing elements for detection include diffusion silicon piezoresistive sensor, strain gauge, and other rigid sensors. However, most of them present such disadvantages as rigidity, difficult to fit the curved surface, high cost and low sensitivity. And it cannot be directly installed on the surface of the cable. In this paper, a conductive hydrogel flexible pressure sensor based on TA/CB@PDMS was developed, using carbon black (CB) as the main conductive medium, with good electrical conductivity, high sensitivity (0.65 kPa−1) and excellent tensile properties (210% tensile breakage). Meanwhile, a salt permeation method (Soak the sensor in LiBr solution) was used to effectively inhibit the sensor’s water from being evaporated and frozen. Its substrate incorporates tannic acid to increase the sensor’s adhesion so that it adheres well to the diagonal cable’s surface. In this paper, the wind speed variation around the diagonal cable and the force distribution on the surface with considering the fluid-structure coupling effect are analyzed by ANSYS WORKBECH finite element simulation. Wind tunnel experiments simulate the sensor’s force response when the inclined cable is subjected to different wind speeds, and the detection accuracy reaches 96.17%. The results show the sensor developed in this paper can realize accurate wind pressure detection of the inclined cable. This study provides a new method for wind pressure detection and health inspection of diagonal cables.

Orientation-dependent extreme shear strain in single-crystalline silicon - from elasticity to fracture

Measuring strain accurately at small length scales poses a significant challenge, making it difficult to obtain precise elastic properties of small materials. This becomes particularly pronounced for test geometries beyond micro-pillars and for materials with high elastic limits and high Peierls stresses. This study investigates the elastic strain limits and strain distribution in micro double shear tests conducted on single-crystalline silicon with different crystallographic orientations. In situ scanning electron microscopy images were used to obtain full-field strain maps using digital image correlation. This local strain analysis approach revealed that the shear zones of the test geometry are not solely under pure shear conditions, but also experience superimposed bending. The local strain analysis approach increases the precision of measured elastic properties to ±15% of the literature value compared to deviations of 75-80% using the traditional global strain analysis approach. This study highlights the limitations of the global strain analysis approach in complex specimen geometries and demonstrates the effectiveness of digital image correlation in accurately determining elastic strain at the small length scale. Furthermore, both the low defect density in the samples as well as the small length scales allow for the exploration of orientation dependent strength levels close to the theoretical limit.

Enhancing cardiomyocytes contraction force measuring in drug testing: Integration of a highly sensitive single-crystal silicon strain sensor into SU-8 cantilevers

The development of efficient tools for predicting drug-induced cardiotoxicity in the preclinical phase would greatly benefit the drug development process. This study presents an SU-8 cantilever integrated with a single-crystal silicon strain sensor to enhance force sensitivity in toxicity screening methods based on changes in the contraction force of cardiomyocytes. The proposed cantilever device enables real-time measurements of cardiomyocytes contraction force with high sensitivity, thereby facilitating the assessment of drug cardiotoxicity. The experimental results obtained herein demonstrate the responsiveness of the proposed platform in detecting forces smaller than 0.02 μN with a force sensitivity that is nearly 17 times higher than those of conventional metal-based strain sensors. Moreover, the integration of strain sensors demonstrates the potential for manufacturing cantilever arrays that can be used in high-throughput screening applications. The developed methodology successfully facilitates in vitro culturing of cardiomyocytes and allows for continuous monitoring of their contraction force. The practical applicability of the proposed platform is further validated through cardiotoxicity analysis. The cultured cardiomyocytes are treated with two cardiovascular drugs, namely verapamil (an L-type calcium channel blocker) and isoproterenol (a sympathomimetic drug targeting β1 and β2 adrenergic receptors), to analyze the drug induced effects in the cardiomyocytes.

Half-Bridge Silicon Strain Gauges with Arc-Shaped Piezoresistors.

Half-bridge silicon strain gauges are widely used in the fabrication of diaphragm-type high-pressure sensors, but in some applications, they suffer from low output sensitivity because of mounting position constraints. Through a special design and fabrication approach, a new half-bridge silicon strain gauge comprising one arc gauge responding to tangential strain and another linear gauge measuring radial strain was developed using Silicon-on-Glass (SiOG) substrate technology. The tangential gauge consists of grid patterns, such as the reciprocating arc of silicon piezoresistors on a thin glass substrate. When two half-bridges are connected to form a full bridge with arc-shaped gauges that respond to tangential strain, they have the advantage of providing much higher output sensitivity than a conventional half-bridge. Pressure sensors tested under pressure ranging from 0 to 50 bar at five different temperatures indicate a linear output with a typical sensitivity of approximately 16 mV/V/bar, a maximum zero shift of 0.05% FS, and a span shift of 0.03% FS. The higher output level of pressure sensing gauges will provide greater signal strength, thus maintaining a better signal-to-noise ratio than conventional pressure sensors. The offset and span shift curves are quite linear across the operating temperature range, giving the end user the advantage of using very simple algorithms for temperature compensation of offset and span shift.

(Best Paper Award, Invited) Manufacturing of Nanosheets and Multilayer Nanogaps in Silicon

Nanogap technology is the basic concept for many promising devices such as localized SOI, multichannel FETs, and resonant tunneling diodes.It will be shown that intrinsic bulk strain in single crystalline silicon can be used to create homogeneous nanogaps with a few nanometer gap distance. The strain has been created by epitaxial growth of Si1-xGex/Si multi-layer stacks on 200 mm (100) silicon wafers. The stacks were patterned by RIE to reveal the side walls for subsequent lateral etching with gaseous hydrochloric acid. In accordance with former investigations [1] we found that a selectivity up to 1000:1 for Si1-xGex/Si can be achieved for Ge-concentrations >30% and growth temperatures T<650°C. XRD measurements, SEM pictures and wagon wheel test structures prove that for the anisotropic lateral etching behavior intrinsic strain is the dominant factor. Furthermore, the crystal orientation plays a dominant role (Fig. 1). Based on this behavior multilayer nanogaps with spacings <10 nm had been fabricated.In a subsequent process nanogaps down to 5 nm have been successfully filled completely with dielectrics and/or metals by low temperature (T<450°C) plasma oxidation, LPCVD as well as ALD (Fig. 2). The resulting nanosheets can be used for device applications.Vertical diodes and lateral MOS transistors with nanogaps and nanosheets have been fabricated. Diodes with a SiO2 gap filling show perfect Fowler-Nordheim tunneling, which proves the high quality of the gap filling process. The electrical properties of nanogap-MOSFETs and various nanogap-diodes will be presented.[1] Destefanis et al., Semiconductor Sci. Technol. 23, 1 (2008) Fig. 1: Wagon wheel structure showing the etch anisotropy of 8 nm SiGe layer in Si Fig. 2: SEM cross section of a multistack of 6 SiGe layers selectively etched and completely filled with LPCVD oxide

Mechanical characteristics and deformation behavior of Al polycrystal reinforced with SiC particles

Molecular dynamics models are established to investigate the influence of silicon carbide (SiC) particle size and strain rate on the mechanical characteristics and deformation behavior of aluminum (Al)/SiC composite. The results show that the ultimate strength of the Al/SiC composite increases from 0.788 to 0.910 GPa as the SiC reinforcement particle size increases from 10 to 30 Å, due to load transfer effects and barriers to dislocation motion. Plastic deformation of Al/SiC composite decreases with increasing SiC particle size, manifested by a lower proportion of atoms subjected to high shear strain for larger SiC particles. The SiC particle size also influences the change in crystal structure during deformation, as shown by the larger particles better supporting the Al matrix in minimizing the dislocation movement. The study shows that the grain boundary and Al/SiC interface play a significant role in the mechanical properties of the composite by impeding the evolution of dislocation and stacking fault. Moreover, the higher strain rates lead to increased ultimate strength and flow stress due to a greater rate of deformation and energy storage. The distribution of shear strain in the composite shows concentrated deformation at the grain boundary, and the large shear-strain region decreases as the strain rate increases. Additionally, higher strain rate leads to more formation of hexagonal-close-packed and amorphous structures, increased dislocation density, and material failure.

Raman strain–shift measurements and prediction from first-principles in highly strained silicon

This work presents how first-principles simulations validated through experimental measurements lead to a new accurate prediction of the expected Raman shift as a function of strain in silicon (Si). Structural relaxation of a strained primitive cell is first performed to tackle the relative displacement of the Si atoms for each strain level. Density functional perturbation theory is then used to compute the energy of the optical phonon modes in highly strained Si and retrieve the strain–shift trend. The simulations are validated by experimental characterization, using scanning electron microscopy (SEM) coupled with backscattering Raman spectroscopy, of silicon microbeams fabricated using a top-down approach. The beams are strained up to 2% thanks to the internal tensile stress of silicon nitride (Si3N4) actuators, allowing a validation of the perturbation theory in high-strain conditions. The results are compared with the phonon deformation potentials theory, and the uncertainty caused by the various parameters found in the literature is discussed. The simulated strain–shift coefficients of $$-175.77\,{\text {cm}}^{-1}$$ (resp. $$-400.85\,{\text {cm}}^{-1}$$ ) and the experimental one of $$-160.99\,{\text {cm}}^{-1}$$ (resp. $$-414.97\,{\text {cm}}^{-1}$$ ) are found for the longitudinal optical LO (resp. transverse optical TO $$_{1}$$ ) mode, showing good agreement.

Multiparameter Single Sensor for Space Silicone Adhesive Monitoring Under High-Vacuum Ultraviolet Exposure

Tilted fiber Bragg grating (TFBG) sensors were demonstrated to simultaneously measure the material thermomechanical and refractometric state in which they are embedded. In this work, for the first time, TFBGs are investigated for three-parameter monitoring of space-qualified NuSil® CV16-2500 silicone operating during high-vacuum ultraviolet (UV) exposure. The first part of the work is focused on the ultraviolet effect on the TFBG spectrum when the sensor is 1) directly exposed to the radiation, 2) covered by a thin cover glass, and with a Kapton layer on top. Successively, the silicone is used as an adhesive in a sandwich structure in which the TFBGs are embedded and exposed under high vacuum to various UV/vacuum UV intensity radiations and durations. The sensors’ spectra were acquired and demodulated to detect the silicone strain–temperature–refractive index variations and correlate the silicone refractometric changes with the equivalent exposure solar hours. The second part of the paper is on silicone degradation state evaluation using the same sensor but during a direct exposure of the adhesive to the radiation. This allowed the UV effects on the silicone to be enhanced but needed a method to compensate for the damaging effect of UV radiation on the TFBG spectrum.

Reciprocating Arc Silicon Strain Gauges.

Currently, silicon-strain-gauge-based diaphragm pressure sensors use four single-gauge chips for high-output sensitivity. However, the four-single-gauge configuration increases the number of glass frit bonds and the number of aluminum wire bonds, reducing the long-term stability, reliability, and yield of the diaphragm pressure sensor. In this study, a new design of general-purpose silicon strain gauges was developed to improve the sensor output voltage while reducing the number of bonds. The new gauges consist grid patterns with a reciprocating arc of silicon piezoresistors on a thin glass backing. The gauges make handling easier in the bonding process due to the use of thin glass for the gauge backing. The pressure sensors were tested under pressure ranging from 0 to 50 bar at five different temperatures, with a linear output with a typical sensitivity of approximately 16 mV/V/bar and an offset shift of -6 mV to 2 mV. The new approach also opens the possibility to extend arc strain gauges to half-bridge and full-bridge configurations to further reduce the number of glass frit and Al wire bonds in the diaphragm pressure sensor.

Low-power silicon strain sensor based on CMOS current reference topology

A strain sensor inspired by a Widlar self-biased current source topology called β-multiplier is developed to obtain a strain-dependent reference current with high supply rejection. The sensor relies on the piezoresistive effect in the silicon MOS transistors that form the current reference circuit. The device behavior is analytically computed and verified with experimental measurements under four-point bending test. A basic implementation with an integrated resistor reaches a strain sensitivity of 2.54 nA/μϵ (gauge factor of 324) for a temperature sensitivity of 52.06 nA/°C. A more advanced full-transistor circuit based on current subtraction principle is furthered implemented in order to reach strain sensitivity up to 12.02 nA/μϵ (gauge factor of 1773) and temperature sensitivity of −28.72 nA/°C. This implementation includes a CMOS active load to tune the strain and temperature sensitivities with a total power consumption between 20 and 150 μW.

Stress-strain engineering of single-crystalline silicon membranes by ion implantation: Towards direct-gap group-IV semiconductors

The introduction of strain into semiconductors offers a well-known route to modify their band structure. Here, we show a single-step procedure for generating such strains smoothly and deterministically, over a very wide range, using a simple, easily available, highly scalable, ion implantation technique to control the degree of amorphization in and around single-crystal membranes. The amorphization controls the density of the material and thus the tension in the neighboring crystalline regions. We have demonstrated up to 3.1% biaxial tensile strain and 8.5% uniaxial strain in silicon, based on micro-Raman spectroscopy. This method achieves strain levels never previously reached in mesoscopic defect-free, crystalline silicon structures. The flexible, gently controllable, single-step process points toward very high mobility complementary metal-oxide-semiconductor devices and easy fabrication of direct-bandgap germanium for silicon-compatible optoelectronics.

Abstract 10810: CMR Feature Tracking Can Estimate Right Ventricular Functional Reserve in Rats with Pulmonary Arterial Hypertension

Introduction: Patient survival with pulmonary arterial hypertension (PAH) is determined from right ventricular (RV) function. CMR feature tracking (CMR-FT) is used to assess RV function. It is not determined, however, whether CMR-FT can assess RV functional reserve in patients with PAH. Hypothesis: We assessed the hypothesis that CMR-FT can estimate RV functional reserve in rats with PAH. Methods: Rats were received injections with monocrotaline (MCT-rats, n=19) or solvent (Ctr-rats, n=5). After four weeks, retrospective ECG-gated cine MR (16 phases/beat) was imaged using a 7-T MRI scanner, and RVEF, RV global longitudinal strain (RVGLS) and RV global circumferential strain (RVGCS) were measured before and after addition of 0.5~3 nmol endothelin-1 (ET-1). After the measurements, trabeculae were dissected from the RVs and electrically stimulated with 2-s intervals ([Ca 2+ ] o 2.0 mM, 24°C). Force and maximum dF/dt (dF/dt max ) were obtained using a silicon strain gauge in the absence and presence of 0.1 μM ET-1. Results: MCT-rats showed higher RV pressure (RVP), lower RVEF, lower RVGLS, lower developed force and lower dF/dt max . RVGLS showed a liner correlation with dF/dt max (r=0.53, p&lt;0.05) and had already been reduced in 5 MCT-rats with preserved RVEF (&gt;50%), suggesting that RVGLS reflects RV contractile properties and is reduced earlier than RVEF. Addition of ET-1 increased RVP in MCT-rats (49.0±19.3 to 59.7±16.8 mmHg, n=6) and Ctr-rats (17.3±7.5 to 20.4±7.8 mmHg, n=2) and increased developed force and dF/dt max in MCT-rats (12.2±5.7 to 17.4±3.1 mN/mm 2 , 0.08±0.03 to 0.14±0.06 mN/mm 2 /sec, n=6). When MCT-rats with preserved-RVEF (&gt;50%) were divided into 2 groups depending on RVGCS, addition of ET-1 further reduced RVGCS in reduced-RVGCS (&gt;-20%) group but not in increased-RVGCS (&lt;-30%) group, suggesting that RVGCS can reflect RV functional reserve. In addition, ET-1 killed MCT-rats with reduced-RVGCS and reduced-RVEF just after its addition. In contrast, ET-1 did not change RVGCS and RVEF in Ctr-rats. Conclusions: CMR-FT can estimate RV functional reserve earlier and more accurately with RVGLS and RVGCS in rats with PAH. Therefore, RV strain with CMR may become an important parameter to assess RV functional reserve in patients with PAH.

Abstract 10163: Ca 2+ Within the Mitochondria Can Affect the Occurrence of Triggered Arrhythmias in Rats with Right Ventricular Hypertrophy

Background: Ca 2+ within the sarcoplasmic reticulum affects the propagation of intracellular Ca 2+ (Ca i ) waves, and the velocity of Ca i waves play important roles in the occurrence of triggered arrhythmias. It is still unknown, however, whether Ca 2+ within the mitochondria (Ca m ) affects the velocity of Ca i wave and the occurrence of arrhythmias in right ventricular (RV) hypertrophy. Objective: To know the roles of Ca m in the velocity of Ca i waves and the occurrence of triggered arrhythmias in rats with RV hypertrophy. Methods: Rats were subcutaneously injected with 60 mg/kg monocrotaline (MCT-rats) or solvent (Ctr-rats). Four weeks after the injection, trabeculae were dissected from the RVs. The force was measured using a silicon strain gauge, Ca m using rhod-2, Ca i using microinjected fura-2 and a CCD camera, and production of reactive oxygen species (ROS) from the slope DCF fluorescence during electrical stimulation. Ca 2+ waves and arrhythmias were induced by electrical stimulation (24°C). Results: MCT-rats showed a higher RV pressure, a larger weight ratio of RV free wall to left ventricle (RV/LV), and faster and larger Ca i waves than Ctr-rats (p&lt;0.01). Among MCT-rats, Ru360 (10 μM), a mitochondrial calcium uniporter (MCU) inhibitor, decreased the occurrence of arrhythmias in trabeculae from rats with a higher RV pressure and a larger RV/LV (n=19). Ru360 decreased rhod-2 signal within trabeculae depending on the RV/LV (r=-0.85, p&lt;0.01, n=10) without changes in Ca i transients, suggesting that inhibition of MCU decreases Ca m in MCT-rats with more severe RV hypertrophy. In addition, Ru360 decreased the velocity of Ca i waves depending on systolic RV pressure (r=-0.60, n=6) and the RV/LV (r=-0.64, n= 7), suggesting that inhibition of MCU decreased the velocity of Ca i waves in MCT-rats with higher RV pressure and more severe RV hypertrophy. Ru360 decreased the slope of DCF fluorescence (p&lt;0.01, n=13). Conclusions: In the hearts with severe RV hypertrophy, inhibition of MCU can cause larger reduction of Ca m , decrease ROS production, and decrease the velocity of Ca i waves and arrhythmias. Thus, in the hearts with severe RV hypertrophy, more Ca 2+ may enter the mitochondria through the MCU, and higher Ca m may be involved in the occurrence of arrhythmias.

B-PO02-019 MITOCHONDRIAL CONNEXIN43 IS INVOLVED IN THE OCCURRENCE OF ARRHYTHMIAS WITH MODULATION OF MITOCHONDRIAL KATP CHANNELS

Connexin43 (Cx43) forms gap junctional channels in cardiac ventricles and exits as hemichannels in the inner mitochondrial membrane (mCx43). To examine whether mCx43 and mitochondrial KATP channels (mKATP) affect the occurrence of arrhythmias. To generate cardiac-specific Cx43-deficient (Cx43-/-) mice, Cx43flox/flox mice were crossed with α-myosin heavy chain (Myh6)-cre+/- mice. The resulting offspring, Cx43-/--mice and their littermates (Cx43+/+-mice) were used. Trabeculae were dissected from ventricles. Force was measured with a silicon strain gauge, Ca2+ within the mitochondria (Cam) with rhod-2, intracellular Ca2+ (Cai) with microinjected fura-2 (22°C). The minimal extracellular Ca2+ concentration (Caomin), at which arrhythmias were induced by electrical stimulation, was determined. Using isolated single ventricular myocytes, mitochondrial membrane potential (ΔΨm) was estimated with tetramethylrhodamine methylester (TMRM), ROS production with 2’,7’-dichlorofluorescein (DCF), and Ca2+ spark frequency with fluo-4 and confocal microscopy. Most of Cx43-/--mice died within 8 weeks (p<0.01). Cx43 was present in the inner mitochondrial membrane in Cx43+/+-mice but not in Cx43-/--mice. Developed force and Cai transients by 0.5 Hz electrical stimulation showed no difference between Cx43-/-- and Cx43+/+-mice (n=7). The Caomin in Cx43-/--mice was lower than that in Cx43+/+-mice (n=5, p<0.01) and was increased by diazoxide (DZX, n=4, p<0.05), suggesting that arrhythmogenesis is increased in Cx43-/--mice and is suppressed by DZX. Ca2+ spark frequency and DCF oxidation rate in Cx43-/--mice were higher (p<0.01) and were decreased by DZX (p<0.01). TMRM fluorescence was decreased after 1 Hz stimulation in Cx43-/--mice, and it was increased by DZX (p<0.01) and was decreased by 5-hydroxydecanoic acid (p<0.01). Rhod-2 signal was increased in Cx43-/--mice but not in Cx43+/+-mice at 4 - 6 mM extracellular Ca2+ (Cao). Cx43 deficiency depolarizes ΔΨm and increases Cam at higher Cao, ROS production, Ca2+ spark frequency, and arrhythmogenesis. All these changes in Cx43-/--mice are suppressed by DZX. Thus, with modulation of mKATP, mCx43 can be involved in the occurrence of arrhythmias.

CMR feature tracking cloud assess right ventricular functional reserve with pulmonary arterial hypertension

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): JSPS KAKENHI, Grant-in-Aid for Early-Career Scientists. Background Pulmonary arterial hypertension (PAH) remains a fatal disorder characterized by elevated pulmonary arterial pressure. Survival of the patients with PAH is determined from right ventricular (RV) function. CMR has become an attractive modality for following up and providing prognosis in such patients, and CMR feature tracking has been used as a newer useful parameter to assess RV function. However, it has not yet been determined whether CMR feature tracking can assess RV functional reserve in patients with PAH. Purpose We investigated whether CMR feature tracking can estimate RV functional reserve using a rat model with PAH. Methods Rats were received injections with monocrotaline (MCT-rats, n = 19) or solvent (Ctr-rats, n = 5). Four weeks after the injections, we performed CMR on 7-T MRI scanner and imaged retrospective ECG-gated cine MR (16 phases/beat). RV ejection fraction (RVEF) and RV strain were analyzed before and after addition of 0.5∼3 nmol endothelin-1 (ET-1). After the measurements, we dissected trabeculae (length = 1.45 ± 0.07 mm, width = 334 ± 27 µm, thickness = 114 ± 6 µm) from the RVs of rat hearts. Trabeculae were electrically stimulated with 2-s intervals at extracellular Ca2+ of 0.7 and 2.0 mmol/L (24°C). Force and maximum dF/dt (dF/dtmax) were then measured using a silicon strain gauge in the absence and presence of 0.1 µM ET-1. Results MCT-rats showed higher systolic RV pressure (RVP), lower RVEF, and lower RV global longitudinal strain (RVGLS) in CMR imaging and showed lower developed force and lower dF/dtmax in their trabeculae. Correlation between RVGLS and dF/dtmax was higher (r = 0.53, p &amp;lt; 0.05) than that between RVEF and dF/dtmax (r = 0.24). In 5 MCT-rats with preserved RVEF (&amp;gt;50%), RVGLS had already been reduced, suggesting that RVGLS is reduced earlier than RVEF. ET-1 increased developed force and dF/dtmax in trabeculae from MCT-rats (12.2 ± 5.7 to 17.4 ± 3.1 mN/mm2 and 0.08 ± 0.03 to 0.14 ± 0.06 mN/mm2/sec, respectively, n = 6), and ET-1 also increased RVP in MCT-rats and Ctr-rats (49.0 ± 19.3 to 59.7 ± 16.8 mmHg in MCT-rats, n = 6, 17.3 ± 7.5 to 20.4 ± 7.8 mmHg in Ctr-rats, n = 2). According to RV global circumferential strain (RVGCS) and RVEF, we could divide MCT-rats into three groups as follows: MCT-rats with reduced-RVGCS (&amp;gt; -20%)/preserved-RVEF (&amp;gt; 50%), MCT-rats with increased-RVGCS (&amp;lt; -30%)/preserved-RVEF and MCT-rats with reduced-RVGCS/reduced-RVEF. ET-1 reduced RVGCS in MCT-rats with reduced-RVGCS/preserved-RVEF, while ET-1 did not change RVGCS in MCT-rats with increased-RVGCS/preserved-RVEF. MCT-rats with reduced-RVGCS/reduced-RVEF died after injection of ET-1. In Ctr-rats, ET-1 did not change RVGCS and RVEF. These results suggest that RVGCS can be useful to assess RV functional reserve. Conclusion CMR feature tracking can estimate RV functional reserve earlier and more accurately than RVEF in rats with PAH. RV strain may become an important parameter to assess RV functional reserve in patients with PAH.