Bioelectronix

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BioElectronix Basics

A great resource about Practical Electronics on wikibooks.

The arduino playground gives a nice overview of electronic components.

Switches

Transistors

4066 QUAD Bilateral Switch

CMOS 4066.png

The CMOS chip 4066 is a quad bilateral switch intended for the transmission or multiplexing of analog or digital signals.

from Practical Electronics: The 4066 contains 4 analogue bilateral switches, each with an active-high enable input (A) and two input/outputs (X and Y). When the enable input is asseted (high), the X and Y terminals are connected by a low impedance; this is the on condition. When the enable is low, there is a high impedance path betwen X and Y, and the switch is off.

The 4066 is pin-compatible with the 4016, but has a significantly lower on impedance and more constant on resistance over the full range of input voltage. Therefore, the 4066 is preferable to the 4016 in most cases.

File:Datasheet 4066.pdf


High Power/Current appliances

H-Bridge

Relais

Relay closeup.jpg
              5v
              |
            relais
              |
  ---[R]----|<
              |
              gnd

Relay connections.jpg

Measuring things

Amplifiers

Op Amp is a short hand term for Operational Amplifier. An operational amplifier is a circuit component that amplifies the difference of two input voltages.

Op-Amps on Practical Electronics

Audio Amplifier, LM386

Multiplexing using 4051 chip

CMOS 4051.jpg



Silicone (PDMS) Bioelectronic Devices

to facilitate the combination of electronics, such as magnets, sensors and LEDs and the cultivation of biological microorganisms we developed a number of prototypes by casting of a transparent silicone rubber. Polydimethylsiloxan PDMS, which can be ordered from dow corning, product name is sylgard 184.

PDMS preparation

  • mix the two components at a ratio of 10:1. a plastic cup is useful for a container.
Base
Curing agent
  • stir and mix thouroughly
P1010183mitgwicht.jpg
  • leave it sit for 2-3 hours to get rid of the bubbles. if you have access to a vacuum you could do it in a few minutes.

PDMS curing

the PDMS will be processable for about 24 hours if you leave it at roomtemperature. for curing its est to put it in an oven at around 60 to 80° C for about 1 h at least. full curing should be achieved after 4 h.

assembling and casting of the bioelectronic device

we prepared all the electronic parts by soldering insulated copper wire to them and attaching a standard connector on the other end.

preparation of parts

first we glued the electronics to a plastic petridish, so they can be fixed and positioned. then a first layer of PDMS is cast on it and left at roomtemperature for 1-2 hours to get rid of bubbles coming out of the magnets. then its cured in the oven for 1 hour. if needed you can cast and cure a second layer on top of it to cover all the electronics.

after casting the second layer

then a well has to be cut or punched out in the middle to hold the microorganisms and the liquids. and finally a small drop of PDMS is poured into the well to seal it. you can allways fill the well again with pdms and cut out a new well.