Team:Valencia/Hardware

From 2009.igem.org

(Difference between revisions)

Revision as of 09:29, 17 October 2009

Experimental Set Up

[under construction. Feel free to read an article while its being developed]

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.

Direct electrical stimulation of cells

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). 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.

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.

Electrostimulation for yeast

Our team has developed an electronic circuit capable of sending electrical impulses to yeast in a large range of voltages [0-100] V and high accuracy at the time of application of these, as they can reach a few milliseconds. As our initial design for neurons and muscles (which was more restricted in terms of voltages and powers), this circuit only serves to control a pixel independently, but it can easily be controlled from any computer.

In this circuit there are two well differentiated parts: the application part, which highlights an adjustable voltage source and the electrodes through which we will stimulate our cells, and the control.

Both are linked by an optocoupler, which serves as the electronic switch. It consists of one LED (on the control) and a phototransistor (part of application), which lets flow current while the collector-emitter diode is lit. To stimulate the diode controlling the time of application accurately, we use the sound card (which has a high frequency) led by the "sound" Matlab function.

But the nature of sound is sinusoidal and therefore also the tension leaves the sound card, and we need to incorporate into our circuit a rectifier-filter control, to ensure that our signal is as continuous as possible. Moreover, the tension that provides the sound card is insufficient to activate the optocoupler. This is the reason why we use two operational amplifiers, one as amplifier and another simply as a voltage follower. 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 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.

@@ Line 22: / Line 22: @@
 <!-- cite -->
-Electroestimulador para levadura.
+*<span style="color:black; align:justify; font-size:11pt; font-family: Verdana">'''Electrostimulation for yeast'''
-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.
+Our team has developed '''an electronic circuit''' capable of sending electrical impulses to yeast in a large range of voltages [0-100] V and high accuracy at the time of application of these, as they can reach a few milliseconds. As our initial design for neurons and muscles (which was more restricted in terms of voltages and powers), this circuit only serves '''to control a pixel independently''', but it can easily be '''controlled from any computer'''.
-En este circuito hay dos partes bien diferenciadas;
+In this circuit there are two well differentiated parts: '''the application part''', which highlights an adjustable voltage source and the electrodes through which we will stimulate our cells, and '''the control'''.
-La parte de aplicación, donde destaca  una fuente de tensión regulable y los electrodos mediante los cuales estimularemos nuestras células.
+Both are '''linked by an optocoupler''', which serves as the electronic switch. It consists of one LED (on the control) and a phototransistor (part of application), which lets flow current while the collector-emitter diode is lit. To stimulate the diode controlling the time of application accurately, '''we use the sound card''' (which has a high frequency) led by the "sound" Matlab function.
-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.
+But the nature of sound is sinusoidal and therefore also the tension leaves the sound card, and we need to incorporate into our circuit a rectifier-filter control, to ensure that our signal is as continuous as possible. Moreover, the tension that provides the sound card is insufficient to activate the optocoupler. This is the reason why  we use two operational amplifiers, one as amplifier and another simply as a voltage follower. 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.