Team:Valencia/Hardware

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=='''Experimental Set Up''' ==
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<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">[under construction. Feel free to read an article while its being developed]
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=='''LEC activation'''==
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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.
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<span style="color:black; align:justify; font-size:11pt; 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.
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*<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">'''Direct electrical stimulation of cells'''
 
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<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">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).
 
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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.
 
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[[Image:V_SoundCircuit.jpg|200px|center]]
 
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<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">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.
 
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Electroestimulador para levadura.
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==='''Electrostimulation for yeast'''===
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Nuestro equipo ha desarrollado un circuito electrónico capaz de enviar impulsos eléctricos a la levadura, en un gran rango de voltajes  [0-100] V , y gran precisión en el tiempo de aplicación de estos, ya que pueden llegar hasta los unos pocos milisegundos.Al igual que nuestro diseño inicial para neuronas y músculos ( el cual estaba más restringido en cuanto a voltajes y potencias), este circuito solo sirve para controlar un pixel de forma independiente, pero pude controlarse fácilmente desde cualquier ordenador.
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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> 
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En este circuito hay dos partes bien diferenciadas;
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The experimental device is composed of the following parts:<br>
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La parte de aplicación, donde destaca  una fuente de tensión regulable y los electrodos mediante los cuales estimularemos nuestras células.  
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*The first one is made of '''a voltage source and two electrodes''' to stimulate the cultures.
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La otra parte es la de control, ambas están acopladas mediante un optoacoplador, que hace la función de interruptor electrónico y está formado por un diodo led (en la parte de control) y un fototransistor (parte de aplicación). Este deja pasar corriente de colector a emisor mientras el diodo esté iluminado.  Para estimular el diodo controlando el tiempo de aplicación con precisión, utilizamos la tarjeta de sonido (que tiene una elevada frecuencia) comandada mediante la función “sound” de Matlab, pero como la naturaleza del sonido es sinusoidal y por lo tanto también la tensión que sale de la tarjeta de sonido, necesitamos incorporar a nuestro circuito de control un rectificador-filtro, para conseguir que nuestra señal sea lo más continua posible. Además la tensión que proporciona la tarjeta de sonido es insuficiente para activar el optoacoplador, es por eso que utilizamos dos amplificadores operacionales, uno como amplificador y otro simplemente como seguidor de tensión. Los amplificadores están alimentados con 5 voltios y masa, de esta forma tendremos 5 voltios a la salida del operacional, cuando la tarjeta de sonido este activa y 0 voltios cuando este inactiva.  
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*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.
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*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>
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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.
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<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">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>
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[[Image: V_ElectroYeast.png|700px]]
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'''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>
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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 [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 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.

V ElectroYeast.png

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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