The Mudcat Café TM
Thread #59418 Message #1921498
Posted By: Amos
29-Dec-06 - 03:43 PM
Thread Name: BS: The Mother of all BS threads
Subject: RE: BS: The Mother of all BS threads
Good for what ails you -- a pico-newton force sensor!!
"The measurement of mass can be carried out at the 10^-21 gram (zeptogram) level (www.aip.org/pnu/2005/split/725-1.html) and of force to the 10^-18 newton (attonewton) level (Arlett et al., in Nano Letters, 2006).
But for many measurements in the cell biology world, this is too
much sensitivity. Forces in this realm are typically at the
piconewton (1 pN=10^-12 newton) level. Examples include the force
applied by the kinesin molecular motor protein to transport vesicles
(6 pN), the force needed to unzip a DNA molecule at room temperature
(9-20 pN), or the force needed to pull a DNA apart by pulling on
opposite ends (65 pN).
Biophysicists need a cost-effective force
sensor that works reliably in water at the pN level. Steven Koch and
his colleagues at Sandia National Labs are well along on delivering
the needed sensor.
The core of the device is a spring one millimeter
long but only a micron thick and is fabricated using a standard
polysilicon micromachining process. This spring operates according
to the classic experiment conducted by Robert Hooke in the 17th
century: the force exerted on the spring equals the amount of the
spring's compression or extension multiplied by a spring constant,
which in this case is about 1 piconewton per nanometer. "
Just in case you ever wondered how much force it takes to rip DNA apart or something like that. A Newton is about the amount of force that a Big Mac exerts when it hits the floor after falling off the table. OR, perhaps, the force delivered by gentle slap of an offended but affectionate girl standing 5'2" in stockings in a room heated to 68.9 degrees F. delivered from a distance of less than two meters. And I am speaking from experience.