Measuring Arm and Hand Joint Kinematics to Estimate Impairment During a Functional Reach and Grasp Task after Stroke.

BACKGROUND: Current approaches to characterizing deficits in upper limb movements after stroke typically focus either on changes in a functional measure, for example, how well a patient can complete a task, or changes in impairment, for example, isolated measurements of joint range of motion. However, there can be notable dissociations between static measures of impairment versus those of function. OBJECTIVE: We develop a method to measure upper limb joint angles during performance of a functional task and use measurements to characterize joint impairment in the context of a functional task. METHODS: We developed a sensorized glove that can precisely measure select finger, hand, and arm joints while participants complete a functional reach-to-grasp task involving manipulation of a sensorized object. RESULTS: We first characterized the accuracy and precision of the glove's joint angle measurements. We then measured joint angles in neurologically intact participants (n = 4 participants, 8 limbs) to define the expected distribution of joint angle variation during task execution. These distributions were used to normalize finger, hand, and arm joint angles in stroke participants (n = 6) as they performed the task. We present a participant-specific visualization of functional joint angle variance which illustrated that stroke participants with nearly identical clinical scores exhibited unique patterns of joint angle variation. CONCLUSIONS: Overall, measuring individual joint angles in the context of a functional task may inform whether changes in functional scores over recovery or rehabilitation are driven by changes in impairment or the development of compensatory strategies, and provide a quantified path toward personalized rehabilitative therapy.

Nanostructured films from hierarchical self-assembly of amyloidogenic proteins.

In nature, sophisticated functional materials are created through hierarchical self-assembly of simple nanoscale motifs. In the laboratory, much progress has been made in the controlled assembly of molecules into one-, two- and three-dimensional artificial nanostructures, but bridging from the nanoscale to the macroscale to create useful macroscopic materials remains a challenge. Here we show a scalable self-assembly approach to making free-standing films from amyloid protein fibrils. The films were well ordered and highly rigid, with a Young's modulus of up to 5-7 GPa, which is comparable to the highest values for proteinaceous materials found in nature. We show that the self-organizing protein scaffolds can align otherwise unstructured components (such as fluorophores) within the macroscopic films. Multiscale self-assembly that relies on highly specific biomolecular interactions is an attractive path for realizing new multifunctional materials built from the bottom up.

Fabrication and characterisation of protein fibril-elastomer composites.

Protein fibrils are emerging as a novel class of functional bionanomaterials. In this paper we make use of their rigidity by combining lysozyme fibrils with a silicone elastomer and demonstrating that at a filling ratio of 10%, the protein fibril composite is at minimum 2 times stiffer than a CNT elastomeric composite of the same filling ratio. We also show that when the elastomer is patterned such that the lysozyme fibrils can be spatially modulated within the elastomer, anisotropic moduli varying by a factor of 2 is produced. By using shear mixing as the fabrication process, the modulus of a 2 wt.% insulin fibril composite is equivalent to a CNT composite with the same filling ratio. In conclusion, we have presented the fabrication and mechanical characterisation of a class of elastomer/protein fibril composite material.