Piranha solution

Abstract: published in Advance ACS Abstracts, June 15, 1995. 0022-365419512099- 10960$09.0010 chemical functionality of the probe tip, the frictional force between the contacting surfaces can be manipulated to vary the "frictional contrast" of the compositional map. Experimental Section A. Sample Preparation. Substrates were prepared by the deposition of 300 nm of gold onto heat-resistant glass (Tempax, Berliner Glas). Prior to gold deposition, the Tempax glass was cleaned by immersion into piranha solution (1:3 HzOz/HzS04), followed by successive sonication in deionized H20, ethanol, and methanol. Caution: The H202/H2S04 solution reacts violently with organic compounds and should be handled with extreme care. Gold was deposited in a cryogenically pumped Edwards 306A vacuum chamber at ambient temperatures using evaporation rates of 0.3-0.4 ds. The gold-coated substrates were then annealed in an oven at 300 "C for 4 h and subsequently under a HZ flame.'' Uncoated Si3N4

Abstract: Successful realization of various BioMEMS devices demands effective surface modification techniques of PDMS elastomer. This paper presents a detailed report on a simple and cost effective approach for surface modification of PDMS films involving wet chemical treatment in two-step processes: primarily involving piranha solution followed by KOH dip to improve hydrophilicity and stability of PDMS surface. Chemical composition of the solution and surface treatment condition have been varied and optimized to significantly increase the surface energy. The effect of surface modification of the elastomer after wet chemical treatment is analyzed using contact angle measurement and FTIR-ATR study. PDMS surface treated in piranha solution with H2O2 and H2SO4 in the ratio of 2:3 followed by a dip in KOH solution for 15 min duration each, demonstrated a maximum reduction of contact angle to ∼27° as compared to untreated sample having a contact angle of ∼110°. The removal of hydrophobic methyl group from elastomer surface and subsequent hydrophilization of surface by wet chemical process was confirmed from FTIR-ATR spectra. This result is also supported by improved adhesion and electrical continuity of deposited aluminum metal film over the modified PDMS surface. Copyright © 2011 John Wiley & Sons, Ltd.

Abstract: It has been found that a common shipping and packaging material for commercial AFM cantilever tips, poly(dimethylsiloxane) (PDMS), causes a thin layer of silicone oil contamination on AFM cantilever tips. Due to the similarity of elemental compositions between silicone oils and AFM cantilevers (both contain silicon and oxygen), it is difficult to detect such contaminants with the widely used surface characterization technique, X-ray photoelectron spectroscopy (XPS), since XPS provides mainly elemental and short-range chemical information. However, by using static time-of-flight secondary-ion mass spectrometry (TOF-SIMS), a technique that is extremely surface-sensitive, silicone oils on AFM cantilevers can easily be identified by their molecular fragments. A simple dip cleaning procedure using a mixture of concentrated sulfuric acid and hydrogen peroxide (piranha solution) was found to be an easy and effective way to remove organic contamination, including silicone oils, from AFM cantilever tips. It has al...