Electronic – What kind of motor is this? Looks more like a solenoid than a motor

A solenoid is sub-optimal for generating ongoing vibration. If the intent were to generate a single shock intermittently, then sure, a solenoid would be a good choice.

For mechanical vibrations (presumably for sensing by human touch), two options are popular:

1. Offset Weight motors, aka pager motors, vibration motors:

   • These are available down to very small sizes, and very low current and voltage ratings, such as 1.5 Volts, 10 mA in 3mm x 3mm x 5 mm, surface mounted.
   • Operating them from your circuit is simple, even trivial.
   • Downside: Very precise start and stop timing is not feasible, and vibration frequency is not simple to modify.
   • Mobile phones (and of course pagers in ancient times) typically use such motors for vibrating ring notification:
     
     _{(Source: eBay.com, Vibrating Micro Motor - 1 to 4.5 V - 13 mm x 7 mm)}

2. Piezoelectric benders aka coin-type speakers:

   • These exist in very small heights, down to under 0.5 mm, but diameter is usually 5 to 10 mm for effective output.
   • Actuated by a haptic driver or haptic controller IC, or even an oscillator at desired vibration frequency, these are a little more complex to drive. Some such haptic piezo actuators require tens or even hundreds of volts, although at minuscule current. The haptic drivers typically generate the required voltages internally.
   • Both vibration frequency and start/stop time can be controlled with great precision.
   • Mobile phone haptic feedback, i.e. the mild buzzing sensation some mobiles offer to indicate the press of a key on a touch screen, for instance, typically use this mechanism.
   • For an example of a piezo haptic driver with an integrated voltage boost converter, see the Texas Instruments DRV8662.
     
     _{(Source: eBay.com, 12mm Piezo Disc)}

You are on thin ice. I agree with your advisor.

What you should do is go back to your advisor and say that now that you have gotten further into the design, experimentation, and testing, that you feel it is more appropriate to use a solenoid instead of a motor. Depending on what lesson he is trying to teach, he might say that's fine, just revise your documentation accordingly, or no you can't do that since a motor was already specified and it's too late to change that.

If the second answer, suck it up and use a motor. Then learn from that to not write tight specs next time until you have done proper design, experimentation, and testing to know what exactly to spec. Writing specs properly is not trivial, and may in fact be what he is trying to have you learn. This sounds like a good lesson that early on in the process you spec what needs to be accomplished, not how. The how part happens later as part of the design.