Output voltage requirement for amplifier in Dropbot

#1

Dear DropBot developers,

We are a quite young group in Hong Kong and our group is a total chemists group. So it is rather difficult to start building such a system. We want to do some cell culture experiment with DMF and it seems that DropBot platform is very suitable for our project. Ryan mentioned somewhere that your cases typically work at 100-150 Vrms and 10kHz (which is +/- 212 V). But we went through a paper about BAY microbioreactor published by Sam H.Au but they used a much more high output voltage around 400-500Vrms.

We asked for the quote for Trek PZD700A ( ±700V, ±100mA output single channel). It is 5800USD and it is a little bit exceed our budget. So I come to ask that whether the PZD 2205(Output ±500V; ±80mA current stable only after 5ms) can be used for moving droplets contains cells around tens of micro-liter. Cause this model is much cheaper than PZD 700A.

Thank you so much for your help and sharing such an excellent design.

Wenting QIU

#2

Hi Wenting,

I’m not sure why they were using such high voltages in that BAY microbioreactor paper. It is an older paper there have been a number of improvements since then that could explain some of the voltage difference:

  1. They were using a larger gap height which requires higher voltages.

  2. They were using lower frequencies (1 kHz); things generally move more easily at higher frequencies (e.g., 10 kHz).

  3. They were using an older surfactant (F68) that is not as effective as newer ones (e.g., Tetronic 90R4).

I know that other people in the lab have moved bacteria and mammalian cell suspensions at 110-140 Vrms since this paper was published.

To answer your second question, I don’t have any personal experience with the PZD2205, but the max voltage/current outputs look fine. My biggest worry would be around capacitive loading. The following figure from our DropBot paper shows the change in amplifier gain with additional loading (i.e., adding more switching boards to the system). You can see that the amplifier gain is stable at frequencies up to ~1 kHz; beyond that, it requires the gain compensation feature:

Inline image 3

Comparing the amplifier loading curves for the PZD700A and
PZD2205, the
PZD2205 looks slightly worse, which may cause problems.

Inline image 1

Inline image 2

If you are not interested in building your own system, you could also check out the new DropBot v3 (http://sci-bots.com). Full disclaimer: I am one of the founders of the company (Sci-Bots) selling these systems.

-Ryan

···

On Fri, Feb 9, 2018 at 4:43 AM, wentin...@gmail.com wrote:

Dear DropBot developers,

We are a quite young group in Hong Kong and our group is a total chemists group. So it is rather difficult to start building such a system. We want to do some cell culture experiment with DMF and it seems that DropBot platform is very suitable for our project. Ryan mentioned somewhere that your cases typically work at 100-150 Vrms and 10kHz (which is +/- 212 V). But we went through a paper about BAY microbioreactor published by Sam H.Au but they used a much more high output voltage around 400-500Vrms.

We asked for the quote for Trek PZD700A ( ±700V, ±100mA output single channel). It is 5800USD and it is a little bit exceed our budget. So I come to ask that whether the PZD 2205(Output ±500V; ±80mA current stable only after 5ms) can be used for moving droplets contains cells around tens of micro-liter. Cause this model is much cheaper than PZD 700A.

Thank you so much for your help and sharing such an excellent design.

Wenting QIU

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#3

Dear Ryan,

Thank you so much for your reply. We finally decided to buy PZD 700A from TREK company.

I just looked through your website and I am very interested in it. But I didn’t find very much detail information about each component, like the quote or assemble guideline.

So you will also in charge of the sales? Maybe it is more convenient to talk through email. I will write you an email through in...@sci-bots.com about our demand.

Thank you.

Best regards,

Wenting

在 2018年2月13日星期二 UTC+8下午10:22:33，Ryan Fobel写道：

···

Hi Wenting,

I’m not sure why they were using such high voltages in that BAY microbioreactor paper. It is an older paper there have been a number of improvements since then that could explain some of the voltage difference:

  1. They were using a larger gap height which requires higher voltages.
  1. They were using lower frequencies (1 kHz); things generally move more easily at higher frequencies (e.g., 10 kHz).
  1. They were using an older surfactant (F68) that is not as effective as newer ones (e.g., Tetronic 90R4).

I know that other people in the lab have moved bacteria and mammalian cell suspensions at 110-140 Vrms since this paper was published.

To answer your second question, I don’t have any personal experience with the PZD2205, but the max voltage/current outputs look fine. My biggest worry would be around capacitive loading. The following figure from our DropBot paper shows the change in amplifier gain with additional loading (i.e., adding more switching boards to the system). You can see that the amplifier gain is stable at frequencies up to ~1 kHz; beyond that, it requires the gain compensation feature:

Inline image 3

Comparing the amplifier loading curves for the PZD700A and
PZD2205, the
PZD2205 looks slightly worse, which may cause problems.

Inline image 1

Inline image 2

If you are not interested in building your own system, you could also check out the new DropBot v3 (http://sci-bots.com). Full disclaimer: I am one of the founders of the company (Sci-Bots) selling these systems.

-Ryan

–
Ryan Fobel, PhD, CEO
Sci-Bots Inc. | http://sci-bots.com
Tel: +1.416.567.6824

On Fri, Feb 9, 2018 at 4:43 AM, went...@gmail.com wrote:

Dear DropBot developers,

We are a quite young group in Hong Kong and our group is a total chemists group. So it is rather difficult to start building such a system. We want to do some cell culture experiment with DMF and it seems that DropBot platform is very suitable for our project. Ryan mentioned somewhere that your cases typically work at 100-150 Vrms and 10kHz (which is +/- 212 V). But we went through a paper about BAY microbioreactor published by Sam H.Au but they used a much more high output voltage around 400-500Vrms.

We asked for the quote for Trek PZD700A ( ±700V, ±100mA output single channel). It is 5800USD and it is a little bit exceed our budget. So I come to ask that whether the PZD 2205(Output ±500V; ±80mA current stable only after 5ms) can be used for moving droplets contains cells around tens of micro-liter. Cause this model is much cheaper than PZD 700A.

Thank you so much for your help and sharing such an excellent design.

Wenting QIU

–

You received this message because you are subscribed to the Google Groups “dropbot-dev” group.

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