Micro-electro-physiology @ HAIP, Ljubljana
Contents
Background Info
Electrochemistry of Plant Life
Video of extracellular measurement of action potential of the venus flytrap
Protocols
On Measuring
Analog to Digital Converter (ADC)
Arduino
Using the arduino we can measure analog voltages using the 6 Inputs ADC. The analog voltage between 0 and 5 V is converted into a 10bit digital number, from 0 to 1023. this can be used to read a value from a sensor, eg a temperature sensor such as the TMP36, a potentiometer or from the electrodes.
Sound Card - Line In
If the potentials we want to measure are mostly changes/modulations in voltages, we can also use the analog-to-digital converter from the sound card. Although that means we cannot measure static voltages, but only fast changes changes, frequencies above ~ 1hz. The sound card is a very fast and precise ADC (single if mono, or double for stereo), sampling at 44khz or up to 96khz and 24 bit resolution.
Amplification
If the signals are to low, such as µV in the example of potentials in plants, we need to amplify the signal and make sure we do not have too much noise or other garbage in our signals. INA118 is a high end instrumental amplifier, with low noise. But maybe cheaper amp might do the trick aswell, such as the LM386
Multiplexing
If we want to measure more inputs we can multiplex them. meaning we measure one input at the time using a chip (4051), which got 8 inputs which are then routed to one single input on the arduino. read more about using the 4051 multiplexer/demultiplexer
Shielding
because every conducting wire, electrode or other parts of a measurement setup are also acting kinda as "antennas", its easy to pick up some artefacts, noise, humms from the electromagnetic environment. typical stuff the measure are the 50Hz humming from all the electric power and lamps or "biipbuupbiiiiip" from mobile phones. to prevent these one can use shielded cables or build a faraday cage around the whole setup.
DIY Glass Pipette Electrodes
Micro Electrode Arrays (MEA)
DIY Microscopy
To be able to observe the pipette we can build our own hacked digital microscopes, using cheap webcams, surveillance video cams or the PS3 eye. see more on the hackteria page.
Slime Mold
preparation of growth media
culture method
Further links to Slimes
paper about growing slime mold as a map of japan
Plant S.M.E.L.A
Setup
Experiments
Venus Fly Trap
Slime Mold
Recordings
testing the microsphone input from webcam as ADC
slime-recording, but measuring something else
we made it, measuring potentials from venus fly trap
Patches for measuring
LineIn Oscilloscope
Participants
Marc Dusseiller, dusjagr labs
Špela Petrič,
Andrej Meglič,
rough schedule
Wednesday
- Introduction
- Experiments in manufacturing DIY electrodes
- intro into DIY microscopy
- using audio and pd for data measurement
- using arduino and pd the measure/visualize data
- start fungi cultures and preparations of plants
- Setup of measurement setup
Thursday
- Preparation of amplifiers and multiplexers
- Setup of measurement setup
- Experiments with plant recordings
Friday
- Wrap-up Workshop: Introduction into all techniques developed
- Preparations of individual pages for a publication using the diffusion layout.
Material for the Book
Example of book about DIY microscopy for Kids (german only)
Interesting Links
http://ediacaran.mech.northwestern.edu/neuromech/index.php/Main_Page