Saturday, 10 March 2012

DuNuoy Padday Tensiometers: 5 Awesomething Things you Should Know

Penetrating one substance at a time

There are many different types of tensiometers on the market.  A tensiometer measures the surface tension of water either statically or dynamically.  It can be measured with mechanically, optically or experimentally measuring different volumes.  Mechanically tensiometers like DuNuoy ring, and DuNuoy Padday rod measure the force on the surface of the water with a probe and attached to a balance.  Optical tensiometers like contact angle or pendant drop calculate the surface tension after taking pictures of the drop size.  Experimentally using flow and different pressures a bubble pressure tensiomer or stagalometers can more or less measure the surface tension of liquids.  See all the different ways of measuring here.

Five awesome things you should know:

1) DuNuoy Padday made by this guy from England in the 1960's and utilized by currently only one company in Finland.  So if you like things English: football, salt and vinegar chips and the Queen or Finnish things: Nokia, Saunas and blondes then you will like their tensiometers. 

2) The minimum volume for measuring using something like a Delta-8 instrument for a microplate is 50 microliters.  That is 1/20000 L of of the beer I will drink tonight (I will only have a pint).  This is even less than what you can measure optically or experimentally.  A normal DuNuoy tensiometer will not even wet the platinum ring with that volume.  Drug, cosmetic and home care companies can use this technology for fast screening of compounds and surfactants for formulations.  Lower volume + less money spent = innovation.

3) No platinum ring.  Platinum is a freaking expensive material (twice the price of gold about 20 dollars a gram).  Why anyone would entrust university students with such a sensitive ring to measure surface tension?  These students are are normally hung over from partying  (amount of beer they drink is multiplied by a factor of 5 in the second point).  The Du Nuoy Padday method utilizes a rod that is difficult to bend and easy to install.  So one can get far more use out of it.  This eliminates the possibility of platinum also being used as a catalyst in Fab labs. 

4) NASA uses these instruments.  What that you say?  NASA.  Yeah NASA.  If a debunk space agency that sent a man to the moon, built multiple rocketships and an international space station (well the good part of it anyway) uses these types of tensiometers then well just about anybody should use these.

5) The method are used for more than just measuring surface tension of aqeous material.  They can be used to measure the surfaces of tissues.  Paul Janmey from University of Pennsylvania does just that.  Different cell types respond to different kinds of surface tension stress.  It might have help understand better embryology from renowned Princeton biology Malcolm Steinberg who recently died.  He stated that ' certain tissues behave like liquids over long timescales with a characteristic surface tension that determines the spatial configuration of interacting tissues and contributes to their arrangement during embryo development..'