Difference between revisions of "Team:Valencia UPV/tzvetelina"

HARDWARE

INTRODUCTION

To address the lack of accessibility to synthetic biology due to the high costs and the level of knowledge required among others, our team has designed Printeria, a fully-equipped bioengineering device capable of automating the process of printing genetic circuits in bacteria.

To ensure a functional, economical and easy-to-use design, collaboration between the hardware and the wet lab teams has been necessary throughout the development process. After several drafts we have achieved a unique design that can be easily transported and replicated at a cost not exceeding xxx € (xxx $). [and whose cost does not exceed xxx €]

Printeria is divided into three main parts dependent on each other:

PRINTERIA

• Overall budget

  Part	Quantity	Cost per unit	Cost
  Structure	----	----	----
  Entry system	----	----	----
  Reaction zone	----	----	----
  Measurement zone	----	----	----
  		TOTAL	----

• Downloads

  • Assembly drawings

  • Printeria's CAD 3D model

STRUCTURE

First of all, it is necessary to design a structure that confines all the elements necessary for the operation of the device inside it and also allows the creation of a sterile atmosphere to carry out the biological reactions.

In order to facilitate its transport, aluminum has been chosen for the frame, which in addition to its low weight, has other great qualities such as great resistance to corrosion and low cost.

It has been used 15x15x1mm square tube profiles joined by plastic corner connectors obtaining as a result a 415x360x280mm chassis. Thanks to the generated blueprints we have been able to contact a company specializing in cutting and handling aluminum that has provided us with all the parts as we required. As it was not possible for us to find plastic connectors that fit our needs, we have decided to design these parts ourselves and then print them on a 3D printer.

Aluminum frame

To complete the structure, it is necessary to create walls that are attached to this frame and contribute to its stability. We have opted for the use of methacrylate due to its attractive appearance, durability and scratch resistance.

As well as the aluminum profiles, the blueprints created were used for ordering the custom-made parts to a company.

Methacrylate cladding

Finally, 4mm diameter countersunk head screws DIN 7991 (M4 L25) and nuts DIN 934 (M4), both made of galvanized steel, were used for joining the methacrylate plates to the frame.

Given the great importance of keeping the reaction zone perfectly horizontal, it is necessary to use levelling feet. In addition, for checking the horizontal position, a bull’s eye level has been installed next to the reaction zone.

Levelling system

ENTRY OF CONSUMABLES

REACTION ZONE

For the main part of the device we needed to be able to reliably and precisely control the movement of liquids involved in the reaction. This ensures that the components mix was intended and then follow every procedure accurately. For this we have decided to use a technology called digital microfluidics, which is based on applying electromagnetic fields to a special surface so that it changes its properties. More precisely we can change the hydrophobicity of the surface as to attract droplets and repel them, ensuring in this way that they follow an established route.

DMF technology (vídeo o esquema explicativo)

To take advantage of this we have designed the PCB under the surface with small pads on which we can apply a high voltage to cause this effect on the coating of our surface.

Explicar que la superficie está compuesta por teflón y un gel (decir cual). Para aguantar el teflón estirado y en su sitio se ha diseñado esta pieza en 3D, la cual también lleva los soportes de las agujas que extraen las gotas de la zona de reacción. Por último, para limitar la evaporación y condensación de agua se ha puesto una tapa.

To be able to control so many pads we are using a HV507, a special driver chip which is a high voltage serial to parallel converter. This means that it takes data one bit at a time and then it displays them all at the same time at a high voltage. This chip can handle up to 64 outputs, meaning that we can connect 64 pads to it. So we only need a total of 6 chips for our entire surface.

For the assembly of the reaction using golden gate we needed to make the droplets with the DNA and the enzymes go through a thermocycling process, which means to change the temperature in cycles.

To take advantage of the digital microfluidics, instead of changing the temperature of a fixed place, we have decided to have the droplet alternating between two places that are at the correct temperature. This means that the temperature of the droplet changes very quickly. And it also means that we only have to stabilize two discrete temperatures instead of changing them constantly, which translates into greater temperature accuracy.

Esquema zonas frías y caliente

Foto RESISTENCIA y PELTIER

At both zones we are going to keep a thermistor monitoring the temperature to complete the control feedback loop. This thermistor is calibrated by using a lab grade thermometer and then adjusted using Steinhart-Hart model coefficients based on the readings (MAY EXPAND)

As the final step in our transformation we need to electroporate our bacteria so that they can absorb the DNA. For this, we need a strong magnetic field, around 1600V. With this purpose, we have used two step-up converters and a simple circuit with a transistor and a capacitor (insert image here). This means that we can apply a voltage during a very short period of time.

MEASUREMENT ZONE

DISINFECTION AND STERILITY

SIMULTANEOUS EXPERIMENTS

RESULTS