Posted by – October 9, 2009
Perl software to control lab syringe pump and valve device, for biology automation, initial version finished today. Works great. Next, need to add the network code, it can be controlled remotely and in synchronization with other laboratory devices, including the bio-robot. This software will be used in the microfluidics project. The software is also part of the larger Perl Robotics project, and a new release will be posted to CPAN next week.
More details on the software follow:
Posted by – July 30, 2009
A basic equation of physics, for those out there building their own centrifuges:
What are RPM, RCF, and g force and how do I convert between them?
The magnitude of the radial force generated in a centrifuge is expressed relative to the earth’s gravitational force (g force) and known as the RCF (relative centrifugal field). RCF values are denoted by a numerical number in “g” (ex. 1,000 x g). It is dependent on the speed of the rotor in revolutions per minute (RPM) and the radius of rotation. Most centrifuges are set to display RPM but have the option to change the readout to RCF.
To convert between the two by hand, use the following equation:
RCF = 11.18 (rcm) (rpm/1000)^2
Where rcm = the radius of the rotor in centimeters.
I’ve now tested the digital microfluidics board via microcontroller. The digital microfluidics board moves a liquid droplet via Electrowetting-on-Dielectric (EWOD). The microcontroller switches the high voltage via a switching board (pictured below, using Panasonic PhotoMOS chips), which controls the +930VDC output by the HVPS (posted earlier), and runs over USB using no cost Processing.org software. This is alpha stage testing.. cleaner version to be built. The goal of course is to scale the hardware to allow automation of microbiology protocols.
Labview is quite expensive, and industrial-grade high voltage switching boards are also quite expensive. So I built my own hardware and the Processing.org language is an easy way to test things. The Processing.org language is a free, open source graphics/media/IO layer on top of Java (as posted previously here).
What follows is the super simple test software written in Processing.org & Java.
Posted by – June 22, 2009
I have designed this high voltage, low current power supply for various experiments in systems & synthetic biology. I have cleaned up the design and I am placing the schematic and board layout online below! This circuit outputs up to +1,866VDC at under 1 mA or can be tapped at various points for +622VDC or +933VDC. This is useful for either DIY Biology or institutional research experiments such as:
- capillary electrophoresis
- digital microfluidics using electrowetting-on-dielectric
- possibly electroporation
- various electrokinetic experiments, such as dielectrophoresis
- (other uses?? Let me know)
- and, lastly of course: making huge sparks that go PAHHHHH-POP
Below is the schematic; read the full post below for the board layout information. Click on the schematic for the full sized version. The schematic operates in stages, so leaving out or bypassing before the 2nd final stage will yield only +933VDC, and leaving out that stage will yield only +622VDC, etc.
Schematic for the HVPS
Systems biologists and synthetic biologists spend a large amount of time moving small liquids from one vial to another. I would say it makes up the majority of their work day, even in a technologically cutting-edge lab which has robotics. Strange, isn’t it, that the most advanced biological science labs in the world are dependent on a human physically moving small drops of liquid samples and reagents around a lab?
Microfluidics aims to move liquids without humans, under computer control. A small flow of DNA in water, for example, might trace a path between two glass plates, within a tiny, etched microchannel. The movement of the flow is controlled by numerous micro-mechanical valves connected to electronics.
Digital microfluidics aims to move liquids without humans, under computer control, using only single droplets under electrical control: no micro-mechanical valves. It works by using electric fields (electrowetting-on-dielectric properties, abbreviated “EWOD”), which polarize water atoms enough to move a very small water droplet across the surface of a computer board. Droplets on the board can split into two, or join together into one.
Standard PCB etching techniques can be used to make low-tech digital microfluidics devices