Junkai Xu

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A microfabricated titration calorimeter having nanowatt sensitivity is presented. The device is achieved by modifying a commercial, suspended-membrane, thin-film thermopile infrared sensor. Chemical reactions are studied by placing a 50.0 nL droplet of one reagent directly on the sensor and injecting nanoliter droplets of a second reagent through a(More)
A panoramic cardiac imaging system consisting of three high-speed CCD cameras has been developed to image the surface electrophysiology of a rabbit heart via fluorescence imaging using a voltage-sensitive fluorescent dye. A robust, unique mechanical system was designed to accommodate the three cameras and to adapt to the requirements of future experiments.(More)
BACKGROUND Increased physical activity can provide numerous health benefits. The relationship between physical activity and health assumes reliable activity measurements including step count and distance traveled. This study assessed step count and distance accuracy for Nike+ FuelBand, Jawbone UP 24, Fitbit One, Fitbit Flex, Fitbit Zip, Garmin Vivofit,(More)
Wavefront propagation in cardiac tissue is affected greatly by the geometry of the wavefront. We describe a computer-controlled stimulator system that creates reproducible wavefronts of a predetermined shape and orientation for the investigation of the effects of wavefront geometry. We conducted demonstration experiments on isolated perfused rabbit hearts,(More)
The foot progression angle is an important measurement related to knee loading, pain, and function for individuals with knee osteoarthritis, however current measurement methods require camera-based motion capture or floor-embedded force plates confining foot progression angle assessment to facilities with specialized equipment. This paper presents the(More)
Arm motion timing is critical during basketball shooting. This study used a body-worn, sensorized basketball sleeve to identify arm motion timing characteristics during basketball free throw and jump shot shooting for trained and novice shooters. Current basketball shooting research has typically focused on arm kinematic angles, while shot timing has(More)
Gait retraining is an important rehabilitation method for re-establishing health gait patterns resulting from disease or injury. Optical marker-based motion capture systems are effective for sensing but aren't used widely, due to cost and lack of portability. Moreover, to perform gait retraining, feedback is needed in addition to sensing. This paper(More)
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