3-D kinematic comparison of treadmill and overground running.

Studies investigating the mechanics of human movement are often conducted using the treadmill. The treadmill is an attractive device for the analysis of human locomotion. Studies comparing overground and treadmill running have analyzed discrete variables, however differences in excursion from footstrike to peak angle and range of motion during stance have yet to be examined. This study aimed to examine the 3-D kinematics of the lower extremities during overground and treadmill locomotion to determine the extent to which the two modalities differ. Twelve participants ran at 4.0m/s in both treadmill and overground conditions. 3-D angular kinematic parameters during the stance phase were collected using an eight camera motion analysis system. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes, then compared using paired t-tests. Of the parameters analyzed hip flexion at footstrike 12° hip range of motion 17°, peak hip flexion 12.7°, hip transverse plane range of motion 8° peak knee flexion 5° and peak ankle excursion range 6.6°, coronal plane ankle angle at toe-off 6.5° and peak ankle eversion 6.3° were found to be significantly different. These results lead to the conclusion that the mechanics of treadmill locomotion cannot be generalized to overground

The influence of barefoot and barefoot inspired footwear on the kinetics and kinematics of running in comparison to conventional running shoes.

Barefoot running has experienced a resurgence in footwear biomechanics literature, based on the supposition that it serves to reduce the occurrence of overuse injuries in comparison to conventional shoe models. This consensus has lead footwear manufacturers to develop shoes which aim to mimic the mechanics of barefoot locomotion. This study compared the impact kinetics and 3-D joint angular kinematics observed whilst running: barefoot, in conventional cushioned running shoes and in shoes designed to integrate the perceived benefits of barefoot locomotion. The aim of the current investigation was therefore to determine whether differences in impact kinetics exist between the footwear conditions and whether shoes which aim to simulate barefoot movement patterns can closely mimic the 3-D kinematics of barefoot running. Twelve participants ran at 4.0 m.s-1±5% in each footwear condition. Angular joint kinematics from the hip, knee and ankle in the sagittal, coronal and transverse planes were measured using an eight camera motion analysis system. In addition simultaneous tibial acceleration and ground reaction forces were obtained. Impact parameters and joint kinematics were subsequently compared using repeated measures ANOVAs. The kinematic analysis indicates that in comparison to the conventional and barefoot inspired shoes that running barefoot was associated significantly greater plantar-flexion at footstrike and range of motion to peak dorsiflexion. Furthermore, the kinetic analysis revealed that compared to the conventional footwear impact parameters were significantly greater in the barefoot condition. Therefore this study suggests that barefoot running is associated with impact kinetics linked to an increased risk of overuse injury, when compared to conventional shod running. Furthermore, the mechanics of the shoes which aim to simulate barefoot movement patterns do not appear to closely mimic the kinematics of barefoot locomotion

Stimuli-Responsive Triblock Copolymer Hydrogels for Extrusion-Based Additive Manufacturing

Thesis (Ph.D.)--University of Washington, 2021Additive manufacturing (AM) is a rapidly expanding field that has revolutionized a number of diverse fields including medicine, construction, aerospace, and robotics. The hardware of AM has seen a dramatic improvement over the years, and there currently exists a vast array of technologies with unique advantages for different applications. Extrusion-based printers, specifically direct-ink write (DIW), are one such AM technology that has seen extensive use due to its relatively low cost and fast print speeds. Despite the rapid growth of AM, research has mostly focused on the adaptation of existing materials for AM applications- leaving material development lagging behind. This has provided an opportunity for materials scientists and engineers to develop novel materials specifically designed for AM applications. Hydrogels are one class of materials that has garnered significant attention for DIW AM. These soft materials mimic the extracellular matrices of cellular environments and have seen extensive use as cell laden inks for 3D bioprinting. Stimuli-responsive hydrogels respond to environmental cues, enabling both effective printing and providing post-print functionality. This thesis focuses on the development of a multi-stimuli-responsive hydrogel platform based on poly(alkyl glycidyl ether) triblock copolymers. Chapter 1 includes an overview of the field of AM and stimuli-responsive hydrogels for extrusion-based AM. Chapter 2 describes the development of the initial temperature- and shear- responsive triblock copolymer hydrogel platform. Chapter 3 further expands this platform through the photo-chemical crosslinking of the hydrogel network and its implementation for the additive manufacturing of catalytically active living materials (AMCALM). Lastly, Chapter 4 continues to advance the functionality the platform through the addition of thiol-reactive monomers for post-functionalization of the hydrogel material

Phosphazene High Polymers and Models with Cyclic Aliphatic Side Groups: New Structure–Property Relationships

Poly­(dichlorophosphazene) is a versatile precursor material for accessing new polymeric materials via the introduction of various side groups by chlorine replacement reactions. Herein, methods are described for the synthesis of a new series of phosphazene single- and mixed-substituent high polymers containing cyclic aliphatic rings, −C_<i>n</i>H_{2<i>n</i>–1} (where <i>n</i> = 4–8). These reactions were preceded by model reactions using small molecule cyclic trimeric phosphazenes. The new high polymers are amorphous, transparent, and film- and membrane-forming materials with a wide range of glass transition temperatures (−60 to +40 °C) depending on the side groups and cosubstituents. All are hydrophobic and resistant to hydrolytic breakdown

Prototype Development of a Temperature-Sensitive High-Adhesion Medical Tape to Reduce Medical-Adhesive-Related Skin Injury and Improve Quality of Care

Medical adhesives are used to secure wound care dressings and other critical devices to the skin. Without means of safe removal, these stronger adhesives are difficult to painlessly remove from the skin and may cause medical-adhesive-related skin injuries (MARSI), including skin tears and an increased risk of infection. Lower-adhesion medical tapes may be applied to avoid MARSI, leading to device dislodgement and further medical complications. This paper outlines the development of a high-adhesion medical tape designed for low skin trauma upon release. By warming the skin-attached tape for 10–30 s, a significant loss in adhesion was achieved. A C14/C18 copolymer was developed and combined with a selected pressure-sensitive adhesive (PSA) material. The addition of 1% C14/C18 copolymer yielded the largest temperature-responsive drop in surface adhesion. The adhesive film was characterized using AFM, and distinct nanodomains were identified on the exterior surface of the PSA. Our optimized formulation yielded 67% drop in adhesion when warmed to 45 °C, perhaps due to melting nanodomains weakening the adhesive–substrate boundary layer. Pilot clinical testing resulted in a significant decrease in pain when a heat pack was used for removal, giving an average pain reduction of 66%