Low Leakage Research Articles

Review of Bioinspired Composites for Thermal Energy Storage: Preparation, Microstructures and Properties

Bioinspired composites for thermal energy storage have gained much attention all over the world. Bioinspired structures have several advantages as the skeleton for preparing thermal energy storage materials, including preventing leakage and improving thermal conductivity. Phase change materials (PCMs) play an important role in the development of energy storage materials because of their stable chemical/thermal properties and high latent heat storage capacity. However, their applications have been compromised, owing to low thermal conductivity and leakage. The plant-derived scaffolds (i.e., wood-derived SiC/Carbon) in the composites can not only provide higher thermal conductivity but also prevent leakage. In this paper, we review recent progress in the preparation, microstructures, properties and applications of bioinspired composites for thermal energy storage. Two methods are generally used for producing bioinspired composites, including the direct introduction of biomass-derived templates and the imitation of biological structures templates. Some of the key technologies for introducing PCMs into templates involves melting, vacuum impregnation, physical mixing, etc. Continuous and orderly channels inside the skeleton can improve the overall thermal conductivity, and the thermal conductivity of composites with biomass-derived, porous, silicon carbide skeleton can reach as high as 116 W/m*K. In addition, the tightly aligned microporous structure can cover the PCM well, resulting in good leakage resistance after up to 2500 hot and cold cycles. Currently, bioinspired composites for thermal energy storage hold the greatest promise for large-scale applications in the fields of building energy conservation and solar energy conversion/storage. This review provides guidance on the preparation methods, performance improvements and applications for the future research strategies of bioinspired composites for thermal energy storage.

Thermally Conductive Shape-Stabilized Phase Change Materials Enabled by Paraffin Wax and Nanoporous Structural Expanded Graphite

Paraffin wax (PW) has significant potential for spacecraft thermal management, but low thermal conductivity and leakage issues make it no longer sufficient for the requirements of evolving spacecraft thermal control systems. Although free-state expanded graphite (EG) as a thermal conductivity enhancer can ameliorate the above problems, it remains challenging to achieve higher thermal conductivity (K) (>8 W/(m·K)) at filler contents below 10 wt.% and to mitigate the leakage problem. Two preparations of thermally conductive shape-stabilized PW/EG composites, using the pressure-induced method and prefabricated skeleton method, were designed in this paper. The expanded graphite formed a nanoscale porous structure by different methods, which enhanced the capillary action between the graphite flake layers, improved the adsorption and encapsulation of EG, and alleviated the leakage problem. The thermal conductivity and the latent heat of the phase-change materials (PCM) prepared by the two methods mentioned above are 9.99 W/(m·K), 10.70 W/(m·K) and 240.06 J/g, 231.67 J/g, respectively, at EG loading by 10 wt.%, and the residual mass fraction was greater than 99% after 50 cycles of high and low temperature. In addition, due to the excellent thermal management capability of PW/EG, the operating temperature of electronic components can be stably maintained at 68–71 °C for about 15 min and the peak temperature can be reduced by at least 23 °C when the heating power of the electronic components is 10 w. These provide novel and cost-effective methods to further improve the management capability of spacecraft thermal control systems.

Development of Hollow Fiber Membranes Suitable for Outside-In Filtration of Human Blood Plasma

Hemodialysis (HD) is a critical treatment for patients with end-stage kidney disease (ESKD). The effectiveness of conventional dialyzers used there could be compromised during extended use due to limited blood compatibility of synthetic polymeric membranes and sub-optimal dialyzer design. In fact, blood flow in the hollow fiber (HF) membrane could trigger inflammatory responses and thrombus formation, leading to reduced filtration efficiency and limiting therapy duration, a consequence of flowing the patients’ blood through the lumen of each fiber while the dialysate passes along the inter-fiber space (IOF, inside-out filtration). This study investigates the development of HF membranes for “outside-in filtration” (OIF) in HD. In OIF, blood flows through the inter-fiber space while dialysate flows within the fiber lumens, reducing the risk of fiber clogging and potentially extending treatment duration. For the OIF mode, the membrane should have a blood-compatible outer selective layer in contact with the patient’s blood. We develop HFs for OIF via liquid-induced phase separation using PES/PVP (polyethersulphone/polyvinylpyrrolidone) blends. The fibers’ surface morphology (SEM, scanning electron microscopy), chemistry (ATR-FTIR—attenuated total reflection-Fourier transform infrared spectroscopy, XPS—X-ray photoelectron spectroscopy), transport properties, and uremic toxin removal from human plasma are evaluated and compared to commercial HFs. These membranes feature a smooth, hydrophilic outer layer, porous lumen, ultrafiltration coefficient of 13–34 mL m2 h−1 mmHg−1, adequate mechanical properties, low albumin leakage, and toxin removal performance on par with commercial membranes in IOF and OIF. They offer potential for more efficient long-term HD by reducing clogging and systemic anticoagulation needs and enhancing treatment time and toxin clearance.

Improving the Thermal Stability of Indium Oxide n-Type Field-Effect Transistors by Enhancing Crystallinity through Ultrahigh-Temperature Rapid Thermal Annealing.

Ultrathin indium oxide films show great potential as channel materials of complementary metal oxide semiconductor back-end-of-line transistors due to their high carrier mobility, smooth surface, and low leakage current. However, it has severe thermal stability problems (unstable and negative threshold voltage shifts at high temperatures). In this paper, we clarified how the improved crystallinity of indium oxide by using ultrahigh-temperature rapid thermal O2 annealing could reduce donor-like defects and suppress thermal-induced defects, drastically enhancing thermal stability. Not only does more crystalline indium oxide depict the high stability of threshold voltage in stringent high-temperature test environments and under positive bias, but it also shows much less degradation under forming gas annealing than as-deposited transistors. Furthermore, we also successfully solved the channel length-dependent threshold voltage problem, which is often observed in oxide transistors, by suppressing defects induced by the metal deposition process and metal doping.

Attoampere Level Leakage Current in Chemical Vapor Deposition-Grown Monolayer MoS2 Dynamic Random-Access Memory in Trap-Assisted Tunneling Limit.

MoS2, one of the most researched two-dimensional semiconductor materials, has great potential as the channel material in dynamic random-access memory (DRAM) due to the low leakage current inherited from the atomically thin thickness, high band gap, and heavy effective mass. In this work, we fabricate one-transistor-one-capacitor (1T1C) DRAM using chemical vapor deposition (CVD)-grown monolayer (ML) MoS2 in large area and confirm the ultralow leakage current of approximately 10-18 A/μm, significantly lower than the previous report (10-15 A/μm) in two-transistor-zero-capacitor (2T0C) DRAM based on a few-layer MoS2 flake. Through rigorous analysis of leakage current considering thermionic emission, tunneling at the source/drain, Shockley-Read-Hall recombination, and trap-assisted tunneling (TAT) current, the TAT current is identified as the primary source of leakage current. These findings highlight the potential of CVD-grown ML MoS2 to extend the retention time in DRAM and provide a deep understanding of the leakage current sources in MoS2 1T1C DRAM for further optimization to minimize the leakage current.

High rectification and gate-tunable photoresponse in 1D-2D lateral van der waals heterojunctions

<p>The self-passivating surfaces and reduced tunneling leakage current enable the creation of ideal Schottky contacts in van der Waals (vdW) semiconductor heterojunctions. However, simultaneously achieving high rectification ratios, low reverse leakage currents, and rapid photoresponse remains challenging. Here, we present a one-dimensional (1D)/two-dimensional (2D) mixed-dimensional heterostructure photodiode to address these challenges. The significant valence band offset and minimal electron affinity difference in this structure ensure high rectification ratios and efficient charge collection. Additionally, the dimensional disparity between the 1D and 2D materials, characterized by a smaller contact area and significant thickness difference, results in low reverse leakage current and a high current on-off ratio. Moreover, it enables gate-tunable band structure transitions. Our device exhibits an exceptional rectifying ratio of 4.7 × 10<sup>7</sup> and a high on-off ratio of 5 × 10<sup>7</sup> (<i>V</i><sub>ds</sub> = 2 V and, <i>V</i><sub>g</sub> = 30 V) at room temperature. Under a gate voltage of 20 V, the photodiode achieves a specific detectivity (<i>D</i><sup><i>*</i></sup>) of 4.9 × 10<sup>14</sup> Jones, a rapid response time of 14 μs, and an extended operational wavelength approaching to <styled-content style-type="number">1550</styled-content> nm. The strategic combination of mixed-dimensional design and band engineering yields a 1D-2D p-n heterojunction photodiode with remarkable sensitivity, repeatability, and fast response, underscoring the potential of vdW semiconductors for advanced optoelectronic applications.</p>

Effects of cellulose nanofibrils on the mechanical and thermal properties of phase change foams based on polyethylene glycol/cellulose nanofibrils/waterborne polyurethane.

Incorporating phase change materials (PCM) into three-dimensional porous network structures could effectively address the leakage problem. In this study, by investigating the effects of different cellulose nanofibrils (CNF) contents on the mechanical and thermal properties of polyethylene glycol (PEG)/CNF/waterborne polyurethane (WPU) phase change foams, a series of leak-proof, lightweight, and stable PEG/CNF/WPU phase change foams were synthesized. Utilizing CNFs as porous support materials could effectively mitigate the leakage of PCMs. Meanwhile, the incorporation of WPU dispersions leads to the formation of CNFs/WPU composite network structure, which enhances the mechanical strength of the phase change foams and further reduces the leakage of PEG. The morphological, crystallographic, chemical, mechanical, and thermal characteristics of PEG/CNF/WPU phase change foams with varying CNF concentrations were comprehensively assessed using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), mechanical testing, and differential Scanning calorimetry (DSC). The research results indicate that phase change latent heat of PEG/CNF/WPU phase change foam containing 0.8 wt% CNF reached 150.54 J·g-1 and demonstrated superior compressive strength, compressive yield stress, and compressive modulus with a remarkably low leakage rate of just 8.57 % after enduring a 30-day leakage test.

Damage mitigation as a strategy to achieve high ferroelectricity and reliability in hafnia for random-access-memory

This study presents a low-damage metallization process for ultra-thin hafnia-based ferroelectric films, achieving high polarization, low leakage currents, and reduced wake-up effect, paving the way for scalable and reliable FeRAM applications.

Performance enhancement of InSnZnO thin-film transistors by modifying the dielectric-semiconductor interface with colloidal quantum dots.

Thin film transistors (TFTs) with InSnZnO (ITZO) and Al2O3 as the semiconductor and dielectric layers, respectively, were investigated, aiming to elevate the device performance. Chemically synthesized CuInS2/ZnS core/shell colloidal quantum dots (QDs) were used to passivate the semiconductor/dielectric interface. Compared with the pristine device, the device with the integrated QDs demonstrates remarkably improved electrical performance, including a higher electron mobility and a lower leakage current. Moreover, the integration of QDs largely mitigates hysteresis in the bidirectional transfer characteristics of the device. Improved negative bias stress stability is also observed in the device with QDs. The performance enhancement is ascribed to the reduction of the trap states induced by the defects in Al2O3, and the screening of electrical dipoles at the Al2O3/ITZO interface. This work proposes a new strategy to passivate the semiconductor/dielectric interface, which not only improves TFT performance, but also holds potential for optoelectronic applications.

Overexpression of StBBX14 Enhances Cold Tolerance in Potato

Potato (Solanum tuberosum L.) is an important food crop, but low temperature affects the potato growth and yield. In this study, the expression level of StBBX14 was significantly increased over 1 h and then gradually decreased under cold stress. The subcellular localization of the StBBX14 protein took place in the nucleus. The OE-StBBX14 transgenic lines showed less leaf damage and significantly lower electrolyte leakage compared with the WT under cold stress, indicating that the overexpression of StBBX14 in the potato enhanced the cold resistance. A transcriptome analysis showed that a total of 2449 and 6274 differentially expressed genes were identified in WT-1 h and WT-12 h, respectively, when compared with WT-0h. A Gene Ontology enrichment analysis revealed that photosynthesis, cell wall, thylakoid, transcription regulator activity, oxidoreductase activity and glucosyltransferase activity were significantly enriched in OE-StBBX14 and WT. A total of 14 distinct modules were generated by a WGCNA analysis based on all differentially expressed genes (DEGs). Four major modules with cold-related genes were isolated. RT-qPCR analysis showed that the expression patterns of eight DEGs were consistent between the qPCR and RNA-seq. These findings illustrate that the StBBX14 played an important role in cold stress in potato and provided a data basis for the genetic improvement of cold resistance traits of potato.

X-Ray Performance of SiC NPN Radiation Detector

In this paper, a silicon carbide (SiC) phototransistor based on an open-base structure was fabricated and used as a radiation detector. In contrast to the exposed and thin sensitive region of traditional photo detectors, the sensitive region of the radiation detector was much thicker (30 μm), ensuring the high energy deposition of radiation particles. The response properties of the fabricated SiC npn radiation detector were characterized by high-energy X-ray illumination with a maximum X-ray photon energy of 30 keV. The SiC npn detector featured stable and clear response to the X-ray within 0.0766 Gy∙s−1 to 0.766 Gy∙s−1 below 300 V. Due to to the low leakage current of less than 1 nA and the fully depleted sensitive region, the bipolar-transistor-modeled SiC npn detector exhibited a clear common-emitter current gain of 5.85 at 200 V (under 0.383 Gy∙s−1), where the gain increased with bias voltage due to the Early effect and reached 7.55 at 300 V. In addition, the transient response of the SiC npn detector revealed a longer delay time than the SiC diode of the same size, which was associated with the larger effective capacitance of the npn structure. The npn detector with internal gain showed great potential in radiation detection.

Surface passivation strategies for CsPbBr3 quantum dots aiming at nonradiative suppression and enhancement of electroluminescent light-emitting diodes.

With many fascinating characteristics, such as color-tunability, narrow-band emission, and low-cost solution processability, all-inorganic lead halide perovskite quantum dots (QDs) have attracted keen attention for electroluminescent light-emitting diodes (QLEDs) and display applications. However, the performance of perovskite QLED devices is intrinsically limited by the inefficient electrical carrier transport capacity. Herein, one facile but effective method is proposed to enhance the perovskite QLED performance by incorporating a short carbon chain ligand of 2-phenethylammonium bromide (PEABr) to passivate the CsPbBr3 QD surface. With the PEABr ligand, the Br- vacancies are passivated, which could eliminate nonradiative recombination of perovskite QDs; thus their optical properties are enhanced. Meanwhile, PEABr can interact with perovskite QDs to adjust the perovskite film morphology, resulting in low current leakage and efficient electron injection. After the PEABr treatment, the CsPbBr3 QD film exhibits strong green emission located at 516 nm, with an average photoluminescence lifetime of 45.71 ns and a photoluminescence quantum yield of up to 78.64%. In addition, the surface roughness of the CsPbBr3 QD film is reduced from 3.61 nm to 1.38 nm, which is essential to prepare a QD film with high surface coverage. As a result, the QLED device with PEABr treated CsPbBr3 QDs exhibits a maximum current efficiency of 32.69 cd A-1 corresponding to an external quantum efficiency of 9.67%, 3.88-fold higher than that of the control device (pure QDs as an emission layer). This research provides an effective strategy for the improvement of the perovskite QLED performance and may be helpful for extending their actual applications.

Leakage and rotordynamic coefficients of labyrinth-scallop seals

Reducing leakages and improving the rotor-dynamic damping characteristics of annular seals is an essential problem of sealing technology. A whole range of damping seals are used to seal the shafts of turbomachines, such as honeycomb, hole pattern, pocket, and scallop seals. To reduce the cost and production time, the scallop seals are increasingly used. They showed quite good dynamic and leakage characteristics in the modernization of compressors in the chemical industry. Some designs of scallop seals are able not only to increase dynamic performance (additional use of swirl brakes in the form of semi-open scallops at the inlet) but also thanks to the hybrid design of the scallop and labyrinth seal made of PEEK material, which ensures a minimum clearance between the seal and the shaft, reduce leakages of pumped fluid. This paper presents the results of calculating the rotordynamic and flow rate characteristics of scallop and labyrinth-scallop seals depending on the operating parameters using computational fluid dynamics (CFD) methods. The CFD was used to calculate the hydrodynamic and rotordynamic characteristics of the seal with shaft whirl. The rotordynamic coefficients were obtained using the frequency excitation method. The obtained characteristics were compared with experimental data available from the literature for annular and labyrinth seals. The study confirmed the relatively low leakages, the high dynamic characteristics of the labyrinth-scallop seals, and the frequency dependence of the stiffness and damping coefficients. It has been confirmed that sickle-shaped scallops create obstacles to the circumferential flow of the working medium. Reducing the circumferential gas flow increases the hydraulic resistance in the grooves and simultaneously minimizes the circulation forces that create shaft whirl, increasing vibration

Development of blue-light GaN based micro light-emitting diodes using ion implantation technology

This study fabricated 10 μm chip size μLEDs of blue-light GaN based epilayers structure with different mesa processes using dry etching and ion implantation technology. Two ion sources, As and Ar, were applied to implant into the LED structure to achieve material isolation and avoid defects on the mesa sidewall caused by the plasma process. Excellent turn-on behavior was obtained in both ion-implanted samples, which also exhibited lower leakage current compared to the sample fabricated by the dry etching process. Additionally, lower dynamic resistance (Rd) and series resistance (Rs) were obtained with Ar implantation, leading to a better wall-plug efficiency of 10.66% in this sample. Consequently, outstanding external quantum efficiency (EQE) values were also present in both implant samples, particularly in the sample implanted with Ar ions. This study proves that reducing defects on the mesa sidewall can further enhance device properties by suppressing non-radiative recombination behavior in small chip size devices. Overall, if implantation is used to replace the traditional dry etching process for mesa fabrication, the ideality factor can decrease from 11.89 to 2.2, and EQE can improve from 8.67 to 11.03%.

Band Alignment of Stacked Crystalline Si/GaN pn Heterostructures Interfaced with an Amorphous Region Using X-Ray Photoelectron Spectroscopy.

The energy band alignment of a stacked Si/GaN heterostructure was investigated using X-ray photoelectron spectroscopy (XPS) depth profiling, highlighting the influence of the amorphous interface region on the electronic properties. The crystalline Si/GaN pn heterostructure was formed by stacking a Si nanomembrane onto a GaN epi-substrate. The amorphous layer formed at the stacked Si/GaN interface altered the energy band of the stacked heterostructure and affected the injection of charge carriers across the junction interface region. This study revealed the interfacial upward energy band bending of the stacked Si/GaN heterostructure with surface potentials of 0.99 eV for GaN and 1.14 eV for Si, attributed to the formation of the amorphous interface. These findings challenge the conventional electron affinity model by accounting for interfacial bonding effects. Electrical measurements of the stacked Si/GaN pn heterostructure diode exhibited a rectifying behavior, consistent with the XPS-determined energy band alignment. The diode outperformed early design with a low leakage current density of 5 × 10-5 A/cm2 and a small ideality factor of 1.22. This work underscores the critical role of the amorphous interface in determining energy band alignment and provides a robust methodology for optimizing the electronic performance of stacked heterostructures. The XPS-based approach can be extended to analyze and develop multi-layered bipolar devices.

Inhibition of hepatocellular carcinoma progression by methotrexate-modified pH-sensitive sorafenib and schisandrin B micelles

Due to the lack of specific symptoms, hepatocellular carcinoma (HCC) is often detected in advanced stages. However, pharmacological systemic therapy, a common clinical treatment for advanced HCC, is prone to serious toxic side effects. To address these issues, we designed a pH-sensitive sorafenib and schisandrin B micelle modified by methotrexate (MTX-SOR/SchB micelles), a nanosystem that combines the advantages of targeted delivery and pH sensitivity, and is capable of improving drug bioavailability and mitigating drug toxic side effects. Firstly, we characterized the physical and chemical properties of micelles, including particle size, Zeta potential, encapsulation efficiency, pH sensitivity and stability. Hepa1-6 cells and fluorescence imaging were used to investigate the targeting ability of MTX-SOR/SchB micelles. Anti-hepa1-6 cell proliferation, invasion, migration, and pro-apoptotic effects were evaluatedin vitro. In addition, HCC tumor-bearing mouse and lung metastasis mouse models were established to investigate the anti-HCC ability of MTX-SOR/SchB micelles, and finally their biological safety was evaluated. We found that the particle size of MTX-SOR/SchB micelles was uniformly distributed, could effectively encapsulation of the drug, had low leakage rate, sensitive pH response, and perfect stability. And MTX-SOR/SchB micelles could target HCC cells with high expression of folate receptorin vitroandin vivo. Moreover, MTX-SOR/SchB micelles could inhibit the proliferation, invasion and metastasis of HCCin vitroandin vivoand promote apoptosis. MTX-SOR/SchB micelles also show good biosafety. In conclusion, MTX-SOR/SchB micelles can effectively enhance the therapeutic effect of HCC, reduce systemic toxicity of drugs, which is expected to be used in clinical treatment.

Layered Deep-UV Optical Crystal KZn₂BO₃Br₂ as a High-κ Dielectric for 2D Electronic Devices.

The development of dielectrics with atomic planes and van der Waals (vdW) interfaces is essential for enhancing the performance of 2D devices. However, vdW dielectrics often have smaller bandgaps compared to traditional 3D dielectrics, limiting their options. This study introduces AZBX (AZn₂BO₃X₂, where A=K or Rb, X=Cl or Br), a nonlinear deep-ultraviolet optical crystal, as a quasi-vdW layered dielectric ideal for 2D electronic devices. Focusing on KZBB, it's excellent dielectric properties, including a wide bandgap, high dielectric constant (high-κ), and smooth interfaces are demonstrated. When used as the top gate dielectric in a KZBB/MoS₂ field-effect transistor (FET) with MoS₂ channels and graphene contacts, the device exhibits outstanding performance, with a steep subthreshold swing (≈ 73mVdec-1), high on/off ratio (≈ 10⁷), negligible hysteresis (0-8 mV), and stable, low leakage current (≈10⁻⁷ Acm- 2) before breakdown. This work expands the 2D material and dielectric landscape and highlights the strong potential of AZBX as high-performance dielectrics.

A Coplanar Crystalline InGaO Thin Film Transistor with SiO2 Gate Insulator on ZrO2 Ferroelectric Layer: A New Ferroelectric TFT Structure

AbstractFerroelectric transistors with a large memory window (MW) and operational stability have been of increasing interest recently. In this study, a ferroelectric thin‐film transistor (FE‐TFT) with a novel metal‐insulator‐semiconductor‐ferroelectric (MISF) structure is proposed. With the ferroelectric layer located under the semiconductor, the TFT process can be similar to a conventional coplanar structure with a SiO2 gate insulator (GI). In this work, both FE and active semiconductors are deposited by spray pyrolysis which is beneficial for large‐area and low‐cost manufacturing. The FE ZrO2 by spray pyrolysis has a nanocrystalline phase, and the semiconductor InGaO shows a polycrystalline structure. The TFT exhibits a MW of 5.6 V with an operating voltage range of −10–10 V. The device shows a low leakage current of 10−12 A, and thus the on/off ratio is >107 at VDS = 1.0 V. The device shows stable performance with increasing temperatures up to 80 °C. The endurance of the device is 5000 cycles at 0.1 Hz pulse with a negligible variation of MW less than 0.1 V, indicating excellent operational stability.

A novel hydraulic swing actuator with high torque density for legged robots

Abstract Hydraulic swing cylinders have tremendous potential in legged robots for their direct heavy torque output to the joints. However, the practical usage faces the obstacles such as internal leakage, oversized shape, and redundant weight, which limit the dynamic performance of legged robots. To solve the above problems, this paper proposes a novel swing hydraulic actuator with a compact size and high torque-to-mass ratio by bending the hydraulic linear actuator, named a circular swing actuator. First, the basic principle of the circular swing cylinder is introduced, then the mechanical structure considering machinability is given, and the ultimate dimension is φ153×70 mm3. The mechanical properties of the circular swing cylinder are verified by numerical simulation and experiments. Its torque-to-weight ratio reaches 471.7 Nm/kg, and the lower internal leakage and zero external leakage are satisfied with the customized sealing system. The step response and position control experiments are conducted, and the frequency and tracking accuracy meet the demands of hydraulically actuated legged robot joints. The proposed hydraulic circular swing actuator offers a good joint actuator choice to design a legged robot with agile motion ability.

Levitation Performance of Radial Film Riding Seals for Gas Turbine Engines

Turbomachinery in gas turbines uses seals to control the leakage between regions of high and low pressure, consequently enhancing engine efficiency and performance. A film riding seal hybridizes the advantages of contact and non-contact seals, i.e., low leakage and low friction and wear. The literature focuses on the leakage performance of these seals; however, one of their fundamental characteristics, i.e., the gap between the rotor and seal surface, is scarcely presented. The seal pad levitates due to the deflection of the springs at its back under the influence of hydrodynamic forces. This study develops a test rig to measure the levitation of film riding seals. A high-speed motor rotates the rotor and gap sensors measure the levitation of the seal pads. Measurements are also compared with the predictions from a Reynolds equation-based theoretical model. Tests performed for the increasing rotor speed indicated that, initially, until a certain rotor speed, the pads adjust their position, then rub against the rotor until another rotor speed is reached, before finally starting levitating with further increased rotor speeds. Moreover, both the measured and predicted results show that pads levitated the most when located 90° clockwise from the positive horizontal axis (bottom of seal housing) compared to other circumferential positions.