Skin potential

A report on an Edgewood Arsenal study on the toxicology of RDX and HMX solns in di-methylsulfoxide, cyclohexanone and acetone states that a study of the toxicology of the expls RDX and HMX in acet, cyclohexanone, and pure and technical grade dimethylsulfoxide (DMSO) was initiated to establish whether there is any danger to plant personnel that handle such mixts. The report contains a review of the existing literature on each expl and on each solvent. It also describes tests that were conducted to establish the intravenous toxicity of the expls in DMSO, skin potential, and the ocular effects of the expls in each solvent. All of these tests were conducted on animals (Ref 77)... 

Partidos, C.D., et al. 2003. Immunity under the skin Potential application for topical delivery of vaccines. Vaccine 21 776. 

EXPOSURE GUIDELINES ACGIH TLV TWA 1 ppm (4.5 mg/m ) OSHA PEL TWA none NIOSH REL TWA Ippm (5 mg/m ) (skin), potential occupational carcinogen IDLH (not determined), carcinogen. 

Flammable solids Respiratory or skin Potential for actual... 

Toxicology LC50 8050 ppm harmful low acute inhalation toxicity si. toxic by ingestion irritating to eyes and skin potential anesthesia hazard in enclosed space TSCA listed Precaution Flamm. liq. dangerous fire risk avoid contact with air or oxygen (explosion danger, adverse effect on subsequent reactions)... 

For DC measurement, it is important that the two electrodes are reference electrodes. If the electrodes are made of different metals or surfaces, then a large exogenic DC voltage (possibly > 1 V) may be generated. Often the best choice is two silver chloride reference electrodes. They can be coupled to the skin or tissue via electrode gel, as shown in Figure 7.1, or via a salt bridge to reduce the DC offset from liquid junction potentials. An invasive electrode as a neutral electrode is the most stable DC reference with a unipolar skin potential recording system. 

DC measurements of skin potentials are of particular interest. Often palmar skin is at about —20 mV with respect to an invasive electrode or a nonpalmar skin surface electrode. Such a voltage is very dependent on the contact electrolyte used, dependent on the liquid junetion potential between the salt bridge and the natural electrolytes (sweat) of the skin. It is found that the measured DC voltage is very dependent not only on the concentration of the salt, but also on the cations (e.g., Na, K" ", Ca ) used. 

To find the electrical properties of file heart is an inverse problem, and in principle it is unsolvable, it is infinitely many source configurations that may result in the measured skin potentials. 

EDA is divided into tonic (level) and phasic (response) phenomena. Both tonic levels (skin conductance level, skin potential level) and responses (SCR, skin potential response) are of interest working with EDA. They are generated under autonomous nerve control of the active organs of the skin, in particular the sweat glands. 

Skin as an Endogenous Bioelectric Source, Skin Potential... 

The skin potential (SP) method measures potential difference between two skin electrodes without current flow. It is the endogenous potential level and response generated by the body itself. Usually the palmar and plantar skin sites are active during a response other sites are passive if the person is relaxed. Both SP electrodes must not be placed on active sites, because if they are equally active no change in potential difference will occur. If both sites are more or less active, the measured potential difference may be small or even with reversed polarity. One electrode is placed at an active site (e.g., the hypothenar), and the other must be at a passive skin site (e.g., the forearm). See more about passive skin sites in Chapter 7.11, Electrode Terminology. 

Earlier Measurement of Both Skin Potential and Skin Conductance... 

Basically EDA has been measured using three different parameters skin potential, skin DC eonductance, and skin AC admittance. In humans, the skin is the largest body organ, with very important tasks with respect to protection against microorganisms, wound healing, temperature control, and water loss. With very easy sensor aeeess, it is easy to measure dielectric and electrical properties of the skin. Pharmaceutical drug delivery can be monitored. 

Tronstad, C., Kalvpy, H., Grimnes, S., Martinsen, 0.G., 2013. Waveform difference between skin conductance and skin potential responses in relation to electrical and evaporative properties of skin. Psychophysiology 50, 1070-1078. 

The skin potential due to electrolytes placed on the skin ,ki and the intrinsic battery potential generated by the sweat glands are usually modeled as two batteries in parallel with internal resistances, as shown in Fig. 17.26. 

Although electrode gels are needed for good skin contact, hydrating electrolytes produce another source of electric potential, known as a skin diffusion potential, in addition to the skin battery. This diffusion potential arises because skin membranes are semipermeable to ions. The magnitude of this skin potential varies as a function of the salt composition in the electrolyte. 

Burbank D. P., and Webster J. G., Reducing skin potential motion artifact by skin abrasion, Med. Biol. Eng. Comput. 16 31-38 (1978). 

Shackel B., Skin drilling A method of diminishing galvanic skin potentials. Am. Jo. Physiol. 72 114—121... 

EOG 0.01-0.1 DC-10 Ag-AgO Skin potential motion Eye position, sleep state, vestibulo-ocular reflex... 

The effects of aldosterone and insulin on toad skin potentiate each other (Andre and Crabbe, 1966) this was taken as an argument for locating the action of insulin at, or close to, the sodium pump , at the basal cell membrane. Herrera (1965) had formulated the same conclusion after a study of the kinetics of sodium transport across toad bladders stimulated by insulin. 

The concept of skin-galvanic reflex includes two phenomena the change in the electrical conductivity of the skin and the development of a potential difference between two sites of the skin surface. The technique used for recording skin potentials does not differ from the one used for recording the steady brain potentials except that the non-polarizing electrodes are larger in diameter. 

The value of the skin potentials depends upon the activity of the sweat glands, cutaneous blood siqiply and tissue polarization it is regulated by the nervous system. Changes in skin potential and electrical conductivity are necessary components of the orienting reflex, and are investigated in the pharmacological analysis of this reflex. 

Skin Charge Density -Skin Elasticity -Skin Potential trap deptlr... 

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