Foldscope to visualize magnetic nano/micro particle motion

Dear all,

First, I would like to thank Prof. Manu and his lab for providing us an opportunity to use Foldscope. It is a wonderful invention.

Now coming to my work on Foldscope:

We work on manipulating magnetic nano particle (MNP) using permanent magnets for drug delivery applications. The magnets are big and strong about 1 to 2 Tesla. A typical bar magnet placed near a glass slide is shown in Figure 1 (0.4 Tesla magnet) and Figure 2 (1 Tesla magnet).

0.4 Tesla magnet.
Fig 1: 0.4 Tesla magnet.
1 Tesla magnet strength.
Fig 2: 1 Tesla magnet strength.

As the magnets are stronger, we found it hard to place them near microscope to capture videos of MNP motion when subjected to magnetic fields. Therefore we needed a system to easily visualize the particle motion with no metal nearby the magnets.

We used Foldscope to visualize MNP and a simple experimental setup is shown in Figure 3. where a small magnet along with the glass slide is also placed near the Foldscope. The video of MNP motion are captured by placing phone camera.

Small magnet placed near foldscope to pull magnetic nanoparticles.
Figure 3: Small magnet placed near Foldscope to pull magnetic nano/micro particles.

Experiments showed MNP motion under high mag lens using both small and big bar magnet. We used two types of particles during experiment (video attached):

  1. Nanoparticle: nano-screen-magr-chitosan-prednisolone (300 nm size-nominal diameter)

Video 1: pulling 300 nm nanoparticle

Video 2: Pulling of 300 nm nanoparticle

Video 3: Pulling of 300 nm size nanoparticle

2. Particle type: piercetm-protein-a-magnetic-beads  (1 um size-nominal diameter)

Video: pulling 1 micron size nanoparticle

We are further looking to work on much bigger magnets such as : Brick magnet (our lab’s previous work). These magnets are bigger than those used for our Foldscope experiments. However, if we try to move the mobile phone closer to the foldscope with the magnet in the vicinity, due to the magnetic field interference phones are turning off. We are currently trying to solve this issue. Any alternative ideas you might have to resolve this issue are welcome and will be appreciated.

Again thank you for Prof. Manu Prakash for providing us with Foldscopes, which turned out to be a handy tool during our experiments. We are planning on carrying out more experiments in the near future using Foldscope to record MNP motion.

Best regards,

Prateek Benhal

2 Comments Add yours

  1. laksiyer says:

    Wow!!! You can see Brownian motion in addition in Video 3. It would be great to study collisions in fluids, what if you put some baker’s yeast ( to simulate say RBCs), or magnetized vs unmagnetized particles.

    The image capturing device need not be a phone camera, if it helps ( I think someone has used a Rasberry Pi).
    Actually, I think it would be interesting if you try this with projection and a remote camera. You might know that the image can be projected quite easily and you could study the particles from the projected image. Given that this will be sufficiently far away from the magnet you could even capture it..

    If you look at Video 2 in the following post, here we projected the image onto a table or a wall and captured it using a phone camera from a distance.

    1. PRATEEK says:

      Thank you so much for the reply. Yes, we can see Brownian motion in Video 3. I worked with yeast cells using electric fields and they reacted well, and it is interesting to see if they react to the magnetic fields.

      I will try using projection, but we require motion of MNPs for quantitative analysis. Hence, will be requiring good HD videos. If projector idea works, then it is going to be amazing. Thank you for the links on nematode.

      Best regards,

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