Assembly of BactoMotor


Our BactoMotor comprises of three devices –Micro-Motor, Direction Controller and Speed Controller.

As their names indicate, the Micro-Motor is the core part of the BactoMotor, and it is small (micrometer scale). The Direction Controller ensures that the propelling force generated by the bacteria translates into a coordinated and directional rotation of the motor. The Speed Controller is used to control the speed of the Bacto-motor

Each device is designed, engineered and tested separately, and functional on its own. After testing and fine-tuning, the devices are assembled to form the final System BactoMotor. The end-results is a micrometer-scale BactoMotor with unidirectional rotation, its speed controllable.


Step 1. Installation of Micro-Motor

The Micro-Motor will be installed into a microchip container (Fig.1a, 1b) with separated chambers. Only one side of the arms of the motor is coated with Biotin (see the Directional Controller).
Figure 1a: Photos of the microchips for micro-motor installation; A: A photo showing the chambers and the valve systems; B: Valve 3 closed; C: Valves 4, 5, 6 and 7 are closed while water is injected into the channel; D: Valve 1 and 7 closed, enclosing the crystal violet solution in the lower 4 chambers; E: The photo of the chamber system
Figure 1b: A diagram showing the Micro-Motor Module installed into a chamber inside the microchip.

Step 2. Introduction of Bacteria

The Bacteria with both Directional Controller and Speed Controller Modules implemented will be introduced to the Micro-Motor (Figure 2).
Figure 2: Introduction of Bacteria into the Micro-Motor

Step 3. Action of Directional Controller

Under the effect of the Direction Controller, all bacteria will only bind onto the sides coated with biotin on each blade of the Micro-Motor.(Fig.3a, 3b)
Fig.3a: The bacteria bounded to the Micro-Motor through action of the Direction Controller Module (Plan View)
Fig.3b: A microscopic view of the Direction Controller Module at work.

Step 4. Removing Excessive Bacteria

The extra bacterial cells will be removed by medium flush. (Fig. 4)
Fig.4: Bacteria not binding to the Micro-Motor will be flushed away by medium flush.

Step 5. BactoMotor in Action

As the Bacteria swims, they will push the motor into rotation. (clockwise as demonstrated in Fig. 5a, 5b)
Fig.5a: The Directional Rotation of the Micro-Motor achieved by the Directional Controller Module
Fig.5b: An animation showing the BactoMotor in action.

Step 6. Using the Speed Controller

To utilize the Speed Controller Module, inducer aTc is added to the Microchip containing the Micro-Motor. Increase in concentration of the inducer aTc will lead to an overall increase in rotational speed of the Bacto-Motor. (Fig. 6a, 6b)
Fig.6a: On additional of 0.5 effective dose of inducer aTc
Fig.6b: On additional of 1.0 effective dose of inducer

On the other hand, dilution/chelation of the inducer will decrease the speed of the motor.