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Demonstration of Flexible Energy Harvester

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Project Overviews

  In this project, we developed a flexible energy harvester based on nanofiber technology. Basically, when the device is squeezed or bent, it generates a changing voltage that generates energy. It has a lot of potential applications,  for example, people can install it on a carpet, and when someone walks by, they can collect the energy generated by it, which is an absolutely environmentally friendly energy source.

  More than that, we also investigated the effects of various factors that affect the voltage generated by the device, such as the ratio of the polymers and nanofibers and the polling time.

  Since I was a first-year student when I started this project, I met some challenges but finally I overcame it with the help of PhD Rajesh. Most importantly, I learned a lot of new knowledge, including theoretical knowledge of nanofibers and nanofibers' production. The whole fabrication process was done in SUTD Chemistry lab.

Fabrication of Nanofibers

Step 1 : Solution Making

1) Wash the magnets and put into the glass bottle.

2) Use a weighing scale to weigh 0.2g of NbCl2 (prevent toxic fume and be fast to prevent oxidation) and 0.667g of Potassium Sorbate and transfer to the glass bottle

3) Use 1ml pipette to transfer 3ml of methanol to a plastic test tube and then to the glass bottle, cap the bottle

4) Put the glass bottle on the vibrating platform, the magnets will stir for 5 min until the solution turns milky white.

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5) Centrifuge the solution to remove chloride for 5 min

6) Extract 3ml of clear solution using a pipette to transfer(1ml pipette for 3 times) to a measuring tube.

7) Then transfer to a small bottle with magnets inside.

8) Transfer 3ml of 2-methoxy ethanol and 0.4g of PVP polymer into the bottle, stir for few hours

Step 2 : Electrospinning

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1) Prepare 5ml clear solution.

2) Cut the needle of a 5ml syringe to make a flat needle top.

3) Use the syringe to store solution and stabilize it above the roller.

4) Wrap an aluminium foil on the roller and use tape to stabilize.

5) Push the syringe so that the volume of the solution is approximately 4.5ml.

6) Press Run bottom to waste several drops.

7) Wipe the needles

8) Switch on the bottom right green light button to on the machine.(adjust the temperature to 42 degrees)

9) Leave the machine for the whole night.

In this step, we just put the product from step 2 into the oven and heat up for 5 hours at 550 degree.

Step 3 : Crystallization 

Step 4 : Verification of the Nanofibers

In this step, we need to use SEM and EDX to verify we got the appropriate nanofibers. SEM will check the particle size of the nanofiber and EDX will check the components of the sample.

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SEM                                                                                                                  EDX

Fabrication of Device / Result

Materials used: ITO Film, PDMS Polymer and KNO Nanofiber

Steps: 

  1. Measure the polymer base and polymer agent ( 10:1 ), then mix them well.

  2. Add KNO nanofiber and mix them together

  3. Pour the solution to the ITO film slowly (avoid generate bubbles)

  4. Heating the product at 60 degrees until the KNO/PDMS become harder

  5. Put another ITO clip on the top

  6. Keep heating for at least 1 hour

  7. Check the conductivity of the product

  8. Then use strong electric field to correct the direction (piezoelectric effect)

  9. Polling at 3kV for different time

  10. Soldering then testing

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We realised there are 3 mean factors  which can affect the performance:

1. The ratio of KNO Nanofiber and PDMS Polymer 

2. The particle size of KNO Nanofiber

3. The Polling time

Now we assume the particle size are same in one sample and do several tests, then I summary what I found based on these experiments:

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Generally we can say that higher ratio of nanofibers  and polymers or longer polling time can generate higher ourtput voltage. 

Polling Process

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