Team:Valencia/Hardware

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Latest revision as of 03:23, 22 October 2009

LEC activation

Our team prides itself in finding ways to link electronics to biology in a direct and innovative fashion. As a consequence we spent considerable time developing circuits and equipment allowing for quick and robust control of cellular physiology.

Electrostimulation for yeast

Our team has developed an electronic circuit capable of applying a voltage between 0 V and 24 V with a precision of 0.1 volts and during time intervals of up to 20 ms. to yeast cultures. This circuit has been used in a first stage to characterize the part BBa_K222000 or what we call LEC. In the characterization, this system supplies the initial estimulation conditions for the cells for the different experiments very precisely, making the results obtained with the luminometer of great confidence.

The experimental device is composed of the following parts:

The first one is made of a voltage source and two electrodes to stimulate the cultures.

The second one is an optocoupler performing the function of an electronic switch. It is composed of a led diode and a phototransistor. The phototransistor will allow to voltage signal while the diode is illuminated.

The last part is the responsible of the fine control of the time period in which the voltage is applied. To do that we stimulate the diode with a PC sound card (it has a precise voltage signal that is transformed by the loudspeakers to reproduce sound) controlled by the function “sound” of the MatLab software.

The output signal of the sound card was modified by a rectifier-filter and then passed through two operational amplifiers (one as an amplifier and the other as a tension follower) in order to produce a very precise signal able to activate the optocoupler. The amplifiers are powered by 5 volts and ground, so we will have 5 volts at the output of the operational when the sound card is active, and 0 volts when idle.

This design allows the stimulus of one channel, one LEC. In order to make a working screen, we will need an array of electrodes connected to a multiplexer. For that, see the next section...

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+        }
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-<div align="justify" style="position:relative; top:-5px; left:70px; width:500px">
+<br>
-== '''Hardware''' ==
+<div align="justify" style="position:relative; margin-top:-265px; margin-left:190px; width:700px; font-size:10pt; font-family: Verdana">
-[under construction. Feel free to read an article while its being developed]
+=='''LEC activation'''==
+<br>
-<span style="color:black; align:justify; font-size:10pt; font-family: Verdana">
+Our team prides itself in '''finding ways to link electronics to biology in a direct and innovative fashion.''' As a consequence we spent considerable time developing circuits and equipment allowing for quick and robust control of cellular physiology.
-Our team prides itself in finding ways to link electronics to biology in a direct and innovative fashion. As a consequence we spent considerable time developing circuits and equipment allowing for quick and robust control of cellular physiology.
 <br><br>
-*'''Direct electrical stimulation of cells'''
+<!-- cite -->
+<br>
+==='''Electrostimulation for yeast'''===
-The first part of hardware design is an electronic amplifier capable of delivering range of voltages between 0 and 13 volts. It is based on an inverting amplifier (fig. 1).
+Our team has developed '''an electronic circuit''' capable of applying a '''voltage between 0 V and 24 V with a precision of 0.1 volts and during time intervals of up to 20 ms.''' to yeast cultures. This circuit has been used in a first stage to characterize the part [http://partsregistry.org/wiki/index.php?title=Part:BBa_K222000 BBa_K222000] or what we call LEC. In the characterization, this system supplies the initial estimulation conditions for the cells for [https://2009.igem.org/Team:Valencia/WetLab/YeastTeam/Results the different experiments] very precisely, making the results obtained with the luminometer of great confidence.<br>
-The input voltage comes from a sound card – a commonly accessible and low cost digital to analog converter. It allows us to control the waveform in an arbitrary fashion using a simple Matlab script.
-[[Image:V_SoundCircuit.jpg|200px|center]]
+The experimental device is composed of the following parts:<br>
-<!-- [photo of the device connected to a sound card] -->
+*The first one is made of '''a voltage source and two electrodes''' to stimulate the cultures.
-The output is connected to platinum electrodes inserted into a buffer over either muscular, neuronal or yeast cells.  We stimulate cells with delta-function pulses every second (or a few of them) to get continuous calcium influx. While muscular and neuronal cells respond to this kind of stimulus naturally, yeast will require some work. We hope that electrical stimulation of yeast could be obtained thanks to a heat-shock response (read more in modeling section) or reported calcium response to electroporation.
+*The second one is '''an optocoupler performing the function of an electronic switch'''. It is composed of a led diode and a phototransistor. The phototransistor will allow to voltage signal while the diode is illuminated.
-<!-- cite -->
+*The last part is '''the responsible of the fine control of the time period in which the voltage is applied'''. To do that we stimulate the diode with a PC sound card (it has a precise voltage signal that is transformed by the loudspeakers to reproduce sound) '''controlled by the function “sound” of the MatLab software'''.<br>
-This design only allows for stimulating one channel at once. While it is useful for proof-of-principle experiments, if we want to make a working screen, we will need an array of electrodes connected to a multiplexer. We are currently developing a device capable of stimulating tens of pixels at once.<br>
+The output signal of the sound card was modified by a rectifier-filter and then passed through two operational amplifiers (one as an amplifier and the other as a tension follower) in order to produce '''a very precise signal able to activate the optocoupler'''. The amplifiers are powered by 5 volts and ground, so we will have 5 volts at the output of the operational when the sound card is active, and 0 volts when idle.
-Chemical stimulation controlled by a computer.<br>
+[[Image: V_ElectroYeast.png|700px]]
+<br><br>
-We are also developing a chemical stimulator – allowing for dropping calcium-wave inducing chemicals onto cells. This is a backup approach in case electrical stimulation does not give us satisfactory results.
+'''This design allows the stimulus of one channel, one LEC. In order to make a working screen, we will need an array of electrodes connected to a multiplexer'''. For that, see [https://2009.igem.org/Team:Valencia/Hardware/iLCD the next section...]<br><br>
-The best approach currently is use of a printer cartridge which can drop 300 hundred picoliter-sized droplets within a fraction of a second. Such a cartridge controlled by a computer allows us to literarily “print” the image on the cells by a single mouse click.
-</span>