Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Content or effect of a constituent of a liquid mixture
Patent
1996-07-11
1998-09-08
Brock, Michael
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Content or effect of a constituent of a liquid mixture
119224, G01N 3300, A01K 6300
Patent
active
058047050
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the invention
The invention relates to a method and an installation for the real-time biological monitoring of physico-chemical parameters of aqueous media using electrical signals emitted by electrically generating aquatic animals.
2. Description of the Related Art.
There is already a device of this type described in the German patent document DE 2 906 884 and making it possible to monitor the quality of the water by means of an electric fish placed in an observation tank. The water of the tank is connected to an electrode for receiving the discharges from the fish which are amplified and recorded. An alarm is provided in the event that limits fixed beforehand are overstepped.
The device operates preferentially with electric fish of the low frequency irregularly pulsating type (Gnathonems petersii and Mormyrus hasselquisti) but also with a low frequency undulating species (Gymnarchus niloticus).
It is based on the continuous measurement of one or more parameters which are not clearly stated; either the strength (from 0 to 5 mA is spoken of), or the voltage of the signals (a digital voltmeter is spoken of), or the frequency (nychthemeral rhythms of discharges from the fish are spoken of) is involved. Since this last quantity is extremely variable for the fish considered, even in the absence of environmental disturbance(s), the exploitation of the method requires complex statistical processing of the discharges.
The device furthermore includes a system for waking the fish so as to preclude having to observe the diurnal rest periods during which its frequency of emission diminishes. This forced activity of the fish gives rise to measurement disturbances; moreover, it is bad for the fish and is therefore not acceptable.
SUMMARY OF THE INVENTION
The inventive idea consists in using high frequency undulating and/or regularly pulsating electric animals, measuring in particular the frequency of emission of the discharges as well as the strength and shape of their signals. Their particular feature is that they emit electrical signals whose characteristics are extremely stable over time when the environmental conditions are themselves stable.
According to a preferred but not limiting embodiment of the invention, a species of fishes known as Apteronotus albifrons is used as test animal.
Apteronotus albifrons emits an undulating signal of low amplitude (a few volts in contact with the fish, a few millivolts within the sensing electrodes) and having a frequency of around 1000 Hz, and which is extremely stable over time (variation of the order of 0.1%) when the environmental conditions are themselves stable. Moreover its signal, far from being sinusoidal, includes a wide spectrum of harmonics which can also be exploited for the bio-monitoring of physico-chemical parameters of aqueous media.
Thus, these tropical fishes continually deliver an electric current, which they modulate in strength, shape and frequency in accordance with various factors in the environment such as temperature, pH, oxygen, the presence of toxic substances, etc.
To summarize, we have as starting point the finding that in a stable environment the characteristics of the electrical signal are also stable, and as a result to exploit the fact that modifications in environmental factors bring about a variation in the characteristics of the electrical signal in terms: harmonics.
Analysis of these three characteristics of the electrical signal as well as a possible study of the motor behavior of the test animal for example with a video system will provide the information exploited by the method and the installation according to the invention.
A first problem to be solved relates to the very marked dependence of the frequency of the fish on the temperature of the water of the tank.
It turns out to be difficult to determine accurately the responses of the fish following variations in physical or chemical factors in the environment such as for example pH and oxygen or the presence of hydrocarbons and other toxic su
REFERENCES:
patent: 4626992 (1986-12-01), Greaves et al.
patent: 4723511 (1988-02-01), Solman et al.
patent: 5140855 (1992-08-01), Gruber
patent: 5176824 (1993-01-01), Willinger et al.
patent: 5307052 (1994-04-01), Harrison et al.
patent: 5322035 (1994-06-01), Hawes et al.
Cretien Didier
Florion Andre
Terver Denis
Thomas Marielle
Brock Michael
Nancie--Centre International De L'Eau
Politzer Jay L.
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