Integrating game-like elements into the classroom is becoming more common given the increasing popularity of video games. Early research shows that educational gamificationimplementing game-like elements into an activity-can increase students' motivation and engagement. The key objectives of this research are: a) investigating student perceptions about gamification within the demography of the authors' institution, and b) understanding if/how the students' overall learning of the course materials improve via gamification. Five engineering courses, all of which are either in the core or are elective classes of the electrical and computer engineering curricula or , were tested with game-like elements over the span of two semesters. The gamified contents were implemented in Moodle using recently available plugins that enabled activities such as badges, experience points tracking with levels, leaderboards, and quizzes with automated feedback. The results were derived from gathering students' views about gamification and course activities from an online survey that each student in the course had the option of completing.A brief summary of the results show that students identified a lack of time and poor timemanagement as key barriers to their learning. Furthermore, students viewed that immediate feedback, and having repeated attempts of similar but different questions (akin to gamified learning through trial and error) were very helpful in their learning. However, students also indicated that the game-like elements, on average, were minimally helpful towards their motivation. This is likely due, in part, to the limited amount of gamification that was incorporated into the courses at this time. The results also show that the combination of gaining experience points and "leveling up" (nor the two individually) is not a strong motivator. Instead, students recommended that activities be tied to extra credit such that they influence the course grade. Survey results also indicated that the groups' of students often played games to win. As such, creating more meaningful goals/challenges for the students to complete may also help with motivation.

A combined theoretical/experimental study of micron size aerosol flows through micro-capillaries of diameter about 100 μm and length about 1 cm is presented. It is shown that under proper conditions at a relatively high velocity of about 100 m/s such an aerosol flow reveals a new manifestation of microfluidics: the Saffman force acting on aerosol particles in gas flowing through a micro-capillary becomes significant thereby causing noticeable migration of particles toward the center line of the capillary. This finding opens up new opportunities for aerosol focusing, which is in stark contrast to the classical aerodynamic focusing methodologies where only particle inertia and the Stokes force of gas-particle interaction are typically used to control particle trajectories. A mathematical model for aerosol flow through a micro-capillary accounting for complicated interactions between particles and carrier gas is presented. This model describes the experimental observables obtained via shadowgraphy for aerosol beams exiting micro-capillaries. It is further shown that it is possible to design a micro-capillary system capable of generating a Collimated Aerosol Beam (CAB) in which aerosol particles stay very close to a capillary center line. The performance of such a CAB system for direct-write fabrication on a substrate is demonstrated. The lines deposited by CAB for direct-write fabrication are shown to exhibit widths of less than 5 μm — superior to ink-jet. Materials deposition based upon directed aerosol flow has the potential of finding application in the fields of flexible electronics, sensors, and solar cells. In this paper, the genesis of a new materials deposition method termed Collimated Aerosol Beam Direct-Write (CAB-DW) is discussed.

Cold spray is a material deposition process used to deposit metallic features for use in applications such as corrosion prevention, dimensional correction and repair, and wear resistant coatings. Micro Cold Spray Direct Write (MCS-DW) is a variant of the cold spray process in which metal particles are accelerated and focused to print fine features on flexible and rigid substrates with no postprocessing required. This paper presents results of numerical studies on the flow of 2 µm and 6 µm diameter silver particles through a converging-diverging micro nozzle with helium gas. The flow of helium was simulated by solving Navier Stokes equation using commercial software. The trajectory and velocity of the aerosol particles were determined using a Lagrangian particle tracking algorithm with a combination of Stokes drag force and Saffman lift force acting on the particles. A comparison of the effect of different corrections applied to Stokes and Saffman forces as well as the effect of Magnus force on the trajectory and velocity of aerosol particles is studied. The effect of particle rotation creating Magnus force is found negligibly small compared to Saffman force for particles of 2 µm diameter, however, the effect is found to be significant for particles of 6 µm diameter. A proposed converging-diverging nozzle is shown capable of accelerating silver particles to velocities as high as 600 m/s and enables aerosol beam widths as thin as 50 µm.

Aerosol flow through a long and tapered micro-capillary (MC) for direct write (DW) technology is typically used with small particles of sizes ranging from 0.2 μm to 10 μm at velocities up to 100 m/s. Earlier research showed that the particles coming through a long MC experience Saffman force that moves the particles towards the center of the beam other than the geometric convergence (due to Stokes drag); thus creating a collimated aerosol beam. It was also established that the additional Saffman force becomes more effective with certain particle diameters and velocities. Therefore, for experimental validation, it is important to accurately measure the particle size distribution and velocities coming out of the long MC. However, the current sizing methods are incapable of measuring particles less than 5 μm due to optical limitations. The current paper presents results using a micro-shadowgraphy system from LaVision Inc. to characterize the flow field. A modification of the particle-sizing algorithm is proposed to measure particles of sub-micron sizes. The modified algorithm can be used to accurately size particles of 1μm diameter.

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