ECG's

Speaking of ECG's... here's a collection of images from an online ECG "library": http://www.ecglibrary.com

Scientists Create Organic Wires for Use in the Human Body

As we all know, circuit elements are concentrated and connected by wires in circuits, while in the body, organs serve as sources and the only form of conductors. Until now. Newly developed organic wires have the potential to replace human nerves, curing diseases of the nervous system ands injuries to the spinal cord, as well as power and interact with man-made electronic devices in the body. Although this technology is in its infancy, these wires should open many doors for future bioelectrical engineers.

Blogging plant

This articles describes a plant in a Japanese cafe thats hooked up to some sensors which use the currents on its leaves to determine how the plant is "feeling" and translates this into daily postings on a blog. Also you can interact with the plant remotely on its blog by activating a flourescent lamp that shines on the plant. Pretty cool.

http://www.slashgear.com/blogging-houseplant-lives-in-japanese-cafe-0718496/

Models of eel cells suggest electrifying possibilities

Electric eel anatomy: The first detail shows stacks of electrocytes, cells linked in series (to build up voltage) and parallel (to build up current). Second detail shows an individual cell...

Engineers long have known that great ideas can be lifted from Mother Nature, but a new paper* by researchers at Yale University and the National Institute of Standards and Technology (NIST) takes it to a cellular level. Applying modern engineering design tools to one of the basic units of life, they argue that artificial cells could be built that not only replicate the electrical behavior of electric eel cells but in fact improve on them. Artificial versions of the eel’s electricity generating cells could be developed as a power source for medical implants and other tiny devices, they say.

The paper, according to NIST engineer David LaVan, is an example of the relatively new field of systems biology. “Do we understand how a cell produces electricity well enough to design one—and to optimize that design?” he asks.

Electric eels channel the output of thousands of specialized cells called electrocytes to generate electric potentials of up to 600 volts, according to biologists. The mechanism is similar to nerve cells. The arrival of a chemical signal triggers the opening of highly selective channels in a cell membrane causing sodium ions to flow in and potassium ions to flow out. The ion swap increases the voltage across the membrane, which causes even more channels to open. Past a certain point the process becomes self-perpetuating, resulting in an electric pulse traveling through the cell. The channels then close and alternate paths open to “pump” the ions back to their initial concentrations during a “resting” state.

In all, according LaVan, there are at least seven different types of channels, each with several possible variables to tweak, such as their density in the membrane. Nerve cells, which move information rather than energy, can fire rapidly but with relatively little power. Electrocytes have a slower cycle, but deliver more power for longer periods. LaVan and partner Jian Xu developed a complex numerical model to represent the conversion of ion concentrations to electrical impulses and tested it against previously published data on electrocytes and nerve cells to verify its accuracy. Then they considered how to optimize the system to maximize power output by changing the overall mix of channel types.

Their calculations show that substantial improvements are possible. One design for an artificial cell generates more than 40 percent more energy in a single pulse than a natural electrocyte. Another would produce peak power outputs over 28 percent higher. In principle, say the authors, stacked layers of artificial cells in a cube slightly over 4 mm on a side are capable of producing continuous power output of about 300 microwatts to drive small implant devices. The individual components of such artificial cells—including a pair of artificial membranes separated by an insulated partition and ion channels that could be created by engineering proteins—already have been demonstrated by other researchers. Like the natural counterpart, the cell’s energy source would be adenosine triphosphate (ATP), synthesized from the body’s sugars and fats using tailored bacteria or mitochondria.

Sleep Trivia

Since we all seem to suffer from sleep-related events…
I recommend the following book; it contains many interesting facts and is extremely helpful to know the influence of sleep on well being.
Edit
About Sleep Debt:
A test for measuring sleep load was termed the Multiple Sleep Latency Test. The MSLT is the amount of time it takes for the person to fall asleep from (0 – 20). They found a direct linear relationship between the average amount of sleep lost and the average change in MSLT scores. They used this test to conclude another result,
“The brain keeps an exact accounting of how much sleep it is owed. In our first study, we restructed the sleep of 10 volunteers to exactly 5 hours each night for 7 nights and observed that the tendency to fall asleep increased progressively each successive day. For the first time in the history of sleep research, we discovered that the effect of each successive night of partial sleep loss carried over, and the effect appeared to accumulate in a precisely additive fashion. In other wods, the strength of the tendency to fall alssep was progressively greater during each successive day with exactly the same amount of sleep each night…” (Dement, 60).

However, this area still needs a more research because there are not enough studies on how long the brain retains an account of our sleeping debts.

The Sleep Cycle

The first round of REM comes after deep sleep.

Stage 1 and Stage 2: The theta waves of light sleep.
Stage 3 and 4: Deep sleep
“In a normal night's sleep, a sleeper begins in stage 1, moves down through the stages, to stage 4, then back up through the stages, with the exception that stage 1 is replaced by REM, then the sleeper goes back down through the stages again. One cycle, from stage 1 to REM takes approximately ninety minutes. This cycle is repeated throughout the night, with the length of REM periods increasing, and the length of delta sleep decreasing, until during the last few cycles there is no delta sleep at all”
http://web.mst.edu/~psyworld/general/sleepstages/sleepstages.pdf

Boston Retinal Implant Prosthesis

Hey guys! We talked a little about the retina last week, so here's a bit on an interesting project discussed in my bioengineering class. The goal is to create a prosthesis to restore vision for visually impaired patients. Simply put, your visual system involves capturing light and focusing it onto the back surface of the eye called the retina. Light detecting cells in the retina processes this information and sends it to the visual cortex of the brain, which in turn interprets what we see.


The group designed a retinal implant that functions for the lost photoreceptors by electrically stimulating the remaining healty cells of the retina. These cells will create discrete points of light, leading to the perception of a shape.








This is a pair of glasses that captures an image with a camera, which is then converted into a pattern of electrical stimulations. There is a transmitting coil on the arm of the glasses that uses radiofrequency transmission to send information and power to the retinal implant. No need to have battery implants or wires going through body!



There is an array of stimulation electrodes in the implant that send current to appropriate areas of the retina corresponding to image.




Excerpt from site on progress of project... very cool stuff =]

"We have performed a total of six experiments on humans. These experiments were relatively brief (i.e. they lasted hours) and involved the surgical placement of an electrode array on to the surface of the retina. Very small electrical currents were delivered to the retina. Some of our patients who had been legally-blind for decades were able to see relatively small spots of light (i.e. like a "pea" as if viewed at arm's length) and occasionally were able to distinguish two spots of light from one another and "see" a line."
For more info! --> http://www.bostonretinalimplant.org