US3889086A

US3889086A - Transducers utilizing electrocapillary action

Info

Publication number: US3889086A
Application number: US484620A
Authority: US
Inventors: Arsene N Lucian
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-10-02
Filing date: 1974-07-01
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

Transducers utilizing electrocapillary action for sensing force, pressure, acceleration motion, and/or vibration and producing an output voltage.

Description

United States Patent 1 [111 3,889,086 Lucian 1 June 10, 1975 TRANSDUCERS UTILIZING [58] Field of Search 200/182, [91, I92, 193,

ELECTROCAPILLARY ACTION [76] Inventor: Arsene N. Lucian, PO. Box 300,

Manasquanj NJ 03736 [56] References Cited [22] Filed July 1 1974 UNITED STATES PATENTS 3,825,709 7/[974 Lucian 8. 200/192 [2!] Appl. No.: 484,620

Related US. Application D t Primary ExaminerHerman J. Hohauser [63] Continuation-impart of Ser. No. 301,268, 0m. 2, F Darby 1972, Pat. No. 3,825,709, which is a continuation-impart of Ser. No. 37,965, May 18, [57] ABSTRACT 1970, Pat. No. 3,70l,868.

Transducers utilizing electrocaplllary aCHOTl for sens- [52] U S Cl 200/19} 2OO/2l4 335/49 ing force, pressure, acceleration motion, and/or vibra- 310/2; 179/! 33 non and producing an output voltage. [51 Int. Cl. HOlh 29/06 19 Claims, 6 Drawing Figures I4 H I I Q 26 l2 27 25 2| Q |4"'\ E L o .............,;a;'-.""" nwnaunn. g: Q ,1

PATENTEDJUH 10 ms SHEET FIG DIGITAL COMPUTER illIl-lllll iM-Ili E )1 N 4 6E 5 U6 P .L 2 N 5 O C R M A TRANSDUCERS UTILIZING ELECTROCAPILLARY ACTION CROSS-REFERENC ES This application is a continuation-in-part of my prior copending application Ser. No. 301,268 filed Oct. 2, 1972, now U.S. Pat. No. 3,825,709 issued July 23, 1974 which in turn is a continuation-in-part of my prior copending application Ser. No. 37,965, filed May 18, I970, now U.S. Pat. No. 3,701,868 issued Oct. 31, I972.

The principles of the electrocapillary effect are discussed in my aforesaid U.S. Pat. No. 3,701,868. The application of the principles to switching devices of various types and forms is disclosed in said patent. In the various devices of that patent the production of mechanical motion and the consequent switching action were obtained by the application of a small electromotive force (emf) across a single mercury-electrolyte interface in a single bore tube (or multiples thereof). This is the motor-action" phase of the electrocapillary effect.

In the aforesaid copending application the electrocapillary action is utilized in conjunction with external means to cause the mercury-electrolyte interface to move in one direction or another and to thereby obtain a resultant emf, or voltage. This is the generator action" phase of the electrocapillary effect. In the copending application several transducer devices utilizing this phase of the effect are disclosed and claimed.

The aforesaid copending application also discloses that if the generator effect is revised and a motion of the mercury column is brought about by a casual effect (e.g. force, pressure, acceleration, impulse, etc.) 21 voltage will be generated between the electrodes of the electrocapillary device.

The present invention is directed to several transducers operating on the electrocapillary principle in which a motion of the mercury-electrolyte interface is brought about by a variety of casual effects, such as force, pressure, impulse, acceleration, temperature, electric or magnetic effects, optical effects, radiation, or other means. The transducers of this invention utilize the causal effect with actuating elements of the transducer or by a remote causal effect producing an impingement of energy of any type upon the actuating elements of the transducer. In either case an emf or voltage is generated between the electrodes of the electrocapillary transducer which is then available for further use or processing.

Transducers according to the present invention also may, in whole or in part, be subject to relative motion with respect to their original space coordinates. Such relative motion in whole or in part, which may be small or large in magnitude, may be used in diverse ways so that the transducer performs sensor functions on the surface of the earth or in space. These functions may include such things as: detection of seismic shocks and tremors caused by earthquakes or artificial man-made explosions of the type produced in prospecting for oil, gas, minerals and so forth; intruder detection; sensing of passing vehicles and walking personnel; and the sensing of acceleration in either terrestrial or extraterrestrial navigation and missle guidance systems as well as in other applicable situations.

It is therefore an object of this invention to provide various types of transducers based on the electrocapillary effect, adapted for use as sensor elements.

Another object is to provide various types of transducers based on the electrocapillary effect adapted for detection of seismic disturbances of geophysical origin and of man-made or artificial explosions used in prospecting for oil, gas, minerals, etc.

A further object is to provide electrocapillary transducers for use as a sensor means for detection of intruders in protected areas.

Another object is to provide electrocapillary transducers for sensing objects or persons in motion such as used in the implementation of automatic equipment.

An additional object is to provide electrocapillary transducers for use as a sensor to detect the passage of vehicles in a given area as for the detection of marching persons in or near the area.

A further object is to provide electrocapillary transducers for use as sensors for the detection and measurement of all types of acceleration, on ground or in space.

A further object is to provide transducers based on the electrocapillary effect in which there is a single interface between a capillary column of liquid conductive metal and an electrolyte solution in contact therewith.

An additional object is to provide transducers based on the electrocapillary effect in which a plurality of capillary columns of liquid conductive metal are used in parallel, each column having a single interface with an electrolyte solution.

Another object is to provide transducers based on the electrocapillary effect in which a plurality of sensor units are connected in series in order to obtain an increased response voltage.

Yet another object is to provide an accelerometer based on the electrocapillary effect in which there is a single interface between a capillary column of liquid conductive metal and an electrolyte solution in contact therewith.

Other objects and advantages of the present invention will become more apparent upon reference to the following specification and annexed drawings in which:

FIG. 1 is a plan view in cross-section similar to FIG. 4 of the copending application, showing portions of a transducer which may be used as a type of seismic sensor;

FIG. 1A is a view of a modification of the transducer of FIG. 1;

FIG. 2 is a plan view in cross-section of another form of sensor using a different type of suspension system for the sensors;

FIG. 3 is a plan view, partly in cross-section of an electrocapillary accelerometer made in accordance with the invention and its associated electronic circuitry',

FIG. 4 is a plan view partly in cross-section, of an electrocapillary accelerometer useful for detection and measurement of accelerations in a vertical plane; and

FIG. 5 is a view of another embodiment of accelerometers.

The theory of the electrocapillary phenomenon is disclosed in the aforesaid patent and copending application, which disclosure is incorporated by reference, and will not be repeated here. In general, motion of an interface formed at the junction of a liquid metal capillary column, such as mercury, and a capillary column of an electrolyte in contact therewith, causes a voltage to be generated between a pair of electrodes one of which is associated with the metal and the other of which is associated with the electrolyte.

FIG. 1 shows a transducer constructed according to the invention which utilizes the electrocapillary effect. The transducer utilizes some of the components of the transducers of FIG. 4 of the aforesaid prior copending application. Here a capillary tube 70 is located between reservoirs 72 and 74 at the ends thereof. Reservoir 72 has an open tubular arm 73 which is closed off by a highly resilient and flexible bellows 79 which can be made, for example, of rubber, plastic or other suitable material.

A pool of a metallic liquid 86, such as mercury, is located in reservoir 72. The mercury extends part way up into the arm 73 leaving a pocket 77 between the closed end of bellows 79 and the mercury in arm 73. The pocket 77 can be filled with air, another suitable gas, or a liquid which will not mix with the mercury 86. A column of mercury 88 extends into the capillary tube 70.

The reservoir 74 includes a lower extension portion 78 which is tipped off. The end of reservoir 74 is sealed off by an elastic membrane 80 which can be of rubber, metal or other suitable material. A cap 82 covers the membrane 80 leaving a pocket 83 therebetween. The pocket 83 is filled with air or other highly compressible g The main portion of reservoir 74 is filled with an electrolyte solution 87 and the reservoir extension 78 has a mercury pool 89. A first output terminal, or electrode 90, passes through the tube into the reservoir 72 to have a portion of it in electrical contact with the mercury 86 and a second output terminal 92 passes into the reservoir extension 78 to have a portion in electrical contact with the mercury pool 89.

A first, porous filter partition 96, for example of fritted glass, is located between the end of capillary tube 70 and the reservoir 74 and a second filter partition 98, which also can be of fritted glass, is located between the mercury pool 89 and the electrolyte 87. Other filter partitions of various degrees of porosity may be used in different sections or locations of the transducer device, in order to make the transducer operation more foolproof. A single interface 99 is formed between the column of mercury 88 and the electrolyte 87 in the capillary tube 70. The operation of the device is described below.

Applying a force to bellows 79 above the end of the column of mercury in arm 73 will cause an impulse of energy in the pocket of liquid or gas 77 in the arm. This impulse is transmitted through the columns of mercury in arm 73, and the mercury in reservoir 86 and in the column 88 to disturb the interface 99 between the mercury column and the electrolyte and to cause it to move. This motion causes a change in surface tension at the single interface 99 and produces a voltage which appears across the two

terminals

90 and 92. The magnitude of the voltage depends upon several factors 1ncluding, for example, the amount of force appliedto the mercury column 88, the size of the column, the size of the interface, the suddenness or speed of application of the force, etc.

As the mercury column 88 moves, the electrolyte 87 in reservoir 74 will also move causing the elastic mem brane 80 to move (expand as the column moves to the right). thereby compressing the gas in the pocket 83 between the membrane and the cap 82. This absorbs the shock of the original energy impulse. Once the force is released from the bellows 79, the gas in pocket 83 will expand and return the membrane 80 to its initial position. This will restore the system to an equilibrium condition with the meniscus at the interface 99 approximately to the same location. At this time, the voltage 0 which has been generated across the

terminals

90 and 92 will drop back to zero. In some cases, depending upon the elasticity and reaction of the membrane 80, there will be an overshoot of opposite polarity of the voltage produced across the

terminals

90 and 92. That is, there will be a movement of the mercury column 88 to the left beyond its original position before the force was applied to the bellows 79.

It should be understood that the response time of the production of the voltage can be controlled by properly selecting the fluid or liquid in the pocket 77 between the bellows 79 and the end of the mercury column 86 in arm 73. That is, if an incompressible liquid is used in pocket 77, there will be a rapid, if not instantaneous 2S reaction of the production of the voltage when a force is applied to bellows 79. On the other hand, if a compressible medium is utilized in pocket 77, the reaction will be delayed by the amount of time it takes the force applied to the bellows 79 to compress the medium and move the body of mercury 86. As should be apparent,

this provides a readily simple way of forming a controlled reaction transducer with desired delay or response characteristics. It should also be understood that the membrane 80 can be damped to control its re- 5 sponse characteristics.

FIG. 1 shows a sensor assembly constructed in accordance with the present invention which utilizes a specific mode of application of the inertial force of a mass [0, which can be a ball or other suitable weight. The

mass 10 is suspended by a spring 12 from a horizontal support ofa frame 14. The frame can be placed on the ground or on any support or location capable of transmitting a vibration or tremor. The electrocapillary tube can be supported by frame 14 but is isolated therefrom.

The mass it) rests on a bar, or lever, 16, which can be bifurcated with a central space between its arms into which cthe mass can extend. Bar 16 is pivotally mounted at one end 18 to the vertical support of the frame and point 18 serves as a fulcrum for the bar. The

lever and fulcrum are selected to obtain a desired mechanical advantage. A connecting rod 20 is attached to the bar 16 and has an end 21, in the shape of a disc, which engages the top of bellows 79. The mode of operation of sensor of FIG. 1 is described below. When frame 14 is subjected to a tremor or vibration, the suspended inertial mass 10 is set in vibratory motion, principally in a vertical up and down oscillation. The impulse generated by this vibration is transmitted by the lever 16 to connecting rod 20 and through the rod 20 to the bellows 79. The oscillatory motion of bellows 79 transmits a force through the intervening fluid or other medium 77 to the meniscus of the mercury column.

This causes the entire Hg column, including the interface 99, to oscillate and thereby generate a voltage between

circuit terminals

90 and 92. Thus the sensing action is completed and translated into an alternating current voltage. This voltage then can be fed into appropriate electrical or electronic circuitry for processing and/or recording.

The sensor of FIG. 1 also has a dual control knob 24a, 24b with concentric shafts on the horizontal support of frame 14 which controls a pair of

fingers

25 and 26. The lower finger 25 engages the underside of a fixed piece 27 on the mass 10. The mass can be moved and locked in a given vertical position by adjusting knob 24a. With this operation the connecting rod can be lifted or depressed slightly to vary its contact pressure with the top face of the bellows. to control the sensitivity of the transducer.

In a similar manner another control knob 24b operates a finger 26 to change the active length of the spring, if such a change is desired to control transducer sensitivity. The length of the lever arm of the force exerted on the bellows 79, and hence the sensitivity of the transducer, may be changed by moving mass 10 along the upper support bar. That is, the upper end of spring 12 is mounted to a movable support.

As is known, the detection of vibrations and tremors occurring in the earth or on the surface of the earth depends primarily on the inertial response of a mass suspended so as to be capable of responding to disturbances of various types, frequencies and intensities in any direction and in any plane. The sensor of FIG. 1 is capable of such response and is capable of use in many instances where, heretofore, instruments such as seis mographs, seisometers, geophones and similar devices, were used. The sensor of H0. 1 has applicability in measuring shocks caused by earthquakes and manmade shocks produced in the exploration for oil, gas, minerals, and other natural resources. In addition, it can respond to vibrations, such as caused by movement of a person or animal in a protected area, to serve as an intruder detection device. Further, it can respond to moving personnel and/or moving vehicles.

FIG. 1A shows a modification of the mass suspension system for a transducer of the type shown in FIG. 1. Here, the inertial mass 10 is located within a cylindrical guide sleeve 100 whose internal diameter is slightly greater than that of the mass. The sleeve is preferably of a material whose inner surface has a minimal frictional resistance. A suitable material is TEFLON. A slot 110 is provided in the sleeve for adjustment purposes and the mass is suspended from a spring 11b whose upper end is attached to a fixed member. The operation of this system is as described with respect to FIG. I. The mass 10, in either case. can be of any other suitable shape.

FIG. 2 shows a modification of the transducer of FIG. 1. Here the mass 10 rests directly on top of bellows 79 and is supported by a wire, or pin, or spring, 30 which is attached to a yoke 32a which is slidable along a lever 32 which is, in the preferred embodiment, a leaf spring. The yoke 32a is attached to the frame 14 by flexible wire or a coil spring 38. Spring 38 in cooperation with leaf spring 32 controls and stabilizes the rest position of the mass 10 supported by the leaf spring. The response frequencies of leaf spring 32 and coil spring 38 can be so adjusted that the elastic response of each member (to incident vibration or tremor) will cooperate with and reinforce the response of the other, thus resulting in much greater sensitivity. The free period of resonant frequency of both members would have to be far removed from the level of frequencies they are expected to sense or detect. The yoke 32a can be moved along the leaf spring 32 to change the length of the lever arm and the transducer sensitivity. The end of the leaf spring 32 remote from the mass is connected at a fulcrum point 34 to a bracket 36 which is mounted to the support arm 14. The bracket 36 also can be moved along the frame 14 to keep the mass 10 centered on bellows 79.

The transducer of FIG. 2 operates in the same manner as that of FIG. 1 and the construction of the electrocapillary device below and to the right of the arm 73 is the same or similar to that shown in FIG. 1. Therefore, a description of the electrocapillary device will not be repeated. Both types of transducers have at least one important advantage over seismometers which utilize sensing by means ofa change in an electromagnetic field. In using an electro-magnetic type seismometer, the location for the instrument must be selected carefully. There is always the possibility of serious electrical interference if the instrument is placed in a location where strong electromagnetic fields exist, such as hightension transmission lines, electrical power generating stations, and other interference-producing machinery and equipment. It is needless to repeat that the electrocapillary sensor is not subject to any such interference. Another advantage of the electrocapillary sensor resides in the fact that it possesses much greater flexibility in adjusting or changing the sensitivity of the system internally as compared to a mechanical or electromagnetic sensor system.

FIG. 3 shows a transducer constructed in accordance with the invention which is used as an accelerometer for sensing acceleration force along either the horizontal or vertical axis. The same reference numerals have been used for similar components. Here, the mercury reservoir 72 end of the tube is closed off at 40. A frictionless slidable piston 42, which can be cup or disc shaped, is located in this end of the tube. A spring 42a is connected between the piston 42 and the end of the tube. The spring may be of the compression type and is constructed to obey accurately a given physical law, for example, Hookes law. A similar piston and

spring arrangement

43, 43a, of equal strength, is located at the other end of the tube in the electrolyte section. The interface or meniscus 99 is held in a null or equilibrium position under the opposing constraints of the two equal spring systems.

To explain the operation of the accelerometer of FIG. 3, consider that there is the platform on which the accelerometer is mounted which is subjected to an acceleration with a component along the longitudinal axis of the instrument and directed from left to right in the diagram. The inertial reaction force of the mass of met cury 86 will act upon the piston and

spring

42, 42a, and move the piston 42 a certain distance A to the left of its rest position. This action will also move interface 99 a corresponding distance A to the left. This distance A is proportional to the acceleration. If the acceleration remains constant, the distance A will remain fixed. If the acceleration is variable, then the distance A will also vary in accordance with variations of the acceleration. The movement of piston 42 causes the mercury column 88 and the electrolyte 87 to move thereby moving the piston 43. In the example described, the piston 43 moves downwardly extending the spring 430. When the acceleration is removed, spring 42a will extend and spring 430 will compress to restore the system to its equilibrium condition. When the component of acceleration is in the opposite direction from that described, the pistons will move oppositely.

The measurement of acceleration is a rather complicated problem. It involves a clear understanding of inertial reaction force in contrast with other kinds of forces, such as gravitational force, centrifugal force, viscosity force, electro-magnetic force, etc. In general it can be said that in a practical instrument, one would have to take into account the interaction between the fundamental force of inertial reaction with one or more of the other forces that come into play in the design of an accelerometer.

One of the features of the electrocapillary accelerometer is that any movement of the interface 99 will automatically generate a voltage at

terminals

90, 92. In this case, the voltage will be proportional to the acceleration. Therefore, a variable acceleration, which normally happens in practice, will generate a variable voltage.

The variable voltage produced by the accelerometer can be modified to yield a regular train of pulses or waves to be fed into a digital computer. Typical circuitry to accomplish this objective is also shown in FIG. 3. Here, the voltage produced at terminal 90, terminal 92 being grounded, is applied to the input ofa high gain amplifier 50 whose output controls the frequency of a voltage controlled oscillator 52. The output of oscillator 52 is applied to pulse generator 54 of suitable construction which produces pulses at a rate corresponding to the frequency of the signal from oscillator 52. The output pulses from generator 54 can be applied directly to a digital computer 56 or any type of data processing system. This is a standard analog to digital converter circuit whose components are conventional. The entire system can generally be classified as a single integrating accelerometer.

The accelerometer of FIG. 3 can be used in a vertical as well as a horizontal position. For use in the vertical position it is preferred to use the construction for the electrolyte arm of the capillary system of FIG. 1. The

spring system

42,42a and 43,43a can be retained or can be replaced by a suitable diaphragm equivalent or still another type of flexible bellows system as long as the restrained, elastic forces can accurately respond to acceleration forces impinging on the inertial mass of mercury and hold the meniscus 99 in any given equilibrium position.

FIG. 4 shows an embodiment of an electrocapillary transducer designed specifically for use as a vertical accelerometer. Here, the electrocapillary devices of FIGS. l-3 have been changed to include a first tube 160 which contains the mercury column 162. The top end of the mercury column is closed off by a member 164, slidable without friction, to which is attached spring 420, preferably constructed to follow Hookes Law, and the piston 42.

A second tube 170 is provided containing the electrolyte 172. The bottom end of the tube is bulb-shaped at 174 and contains a small quantity of mercury I76 therein. The two tubes I60 and 170 are joined by a capillary tube 180 which is generally S-shaped. The single interface 182 occurs in the capillary tube 180. The top of the electrolyte tube 170 is sealed off by a member 186 to which is connected spring 43a and piston 43. An electrode 187 is immersed in the mercury pool 176 and an electrode 188 in the mercury column 162.

The operation of the vertical accelerometer of FIG. 4 is similar to that of the horizontal accelerometer of FIG. 3. Namely, any component of vertical inertial ac celeration will cause the motion of the inertial mass, i.e. the mercury column, to initiate the motion responsive to the acceleration force acting on the whole system. The initial action of the mercury column causes

pistons

42,43 to move and the

springs

42a, 43a to elongate or compress without any interference due to gravitational acceleration. This moves the mercury column I62 and the interface 182 to generate a voltage across the two terminals 187 and 188. The voltage generated can be gonverted into digital form using the circuitry of FIG.

In the vertical accelerometer of FIG. 4, the electrocapillary force offsets and counterbalances the gravltational force at the interface. Therefore, the mercury column responds only to the inertial forces. This greatly simplifies the design and operation of an accelerometer.

In each of the embodiments of accelerometers of FIGS. 3 and 4, there are no mechanical or electromechanical pickoffs needed to produce the voltage. Instead, the voltage corresponding to the inertial acceleration component is generated directly at the terminals of the electrocapillary device.

FIG. 5 shows a further embodiment which can be used as a linear intertial accelerometer and in which two electrocapillary transducers can be connected in series to increase the voltage sensed. This embodiment is a modification of the transducer shown in FIG. 3 and the same reference numbers used where applicable. Here there are two electrocapillary arms 202a and 202b extending from adjoining but separate mercury reservoirs 200a and 20019 which is a part of the complete envelope. The construction and action of the spring system formed by

elements

42 and 420 will not be repeated. An output voltage for arm 202a is taken across terminals a and 92a and a bias voltage is supplied thereto by a source 2050 if needed for circuit adustment or sensitivity control purposes. Similarly, the output voltage of the arm 202b is taken across the terminals 92a, 92b. Each of the electrocapillary tubes has a single interface 99 between the mercury and the electrolyte.

A main elastic diaphragm 215 is mounted in the reservoir 200. This diaphragm is responsive to accelerations to change its position and thereby change the position of the meniscus in each of the arms 202 to generate the voltage across the respective pairs of

electrodes

90, 92. For example, assuming a component of acceleration is sensed which will move the diaphragm M5 to the left, the length of the mercury column in arm 2020 is increased while the length of the mercury column in arm 202b is moved to its left and decreased. This will disturb the interface in each column and produce a voltage across each of the sets of terminals 900, 92a and 92b of opposite polarity. The two voltages can be added algebraically to double the total voltage. This voltage can be then used in any desired manner to indicate the component of acceleration.

The piston and spring 42,420 at each end of the device will be compressed or extended depending upon the direction of movement of the mercury columns. When the acceleration component is removed, the spring system will restore the device to an equilibrium condition. The diaphragm 215 can be replaced by other suitable responsive devices, for example a spring system obeying Hookes Law.

What is claimed is:

I. An electrocapillary transducer comprising an envelope including a tube portion having capillary transverse interior dimensions, a metallic liquid contained within said envelope and extending into said tube portion, a liquid electrolyte contained within said envelope and extending into said tube portion, said metailic liquid and said electrolyte being immiscible in each other and forming a single interface only in said capillary tube, electrode means respectively in electrical contact with said metallic liquid and said electrolyte, means external of said envelope for applying a force across said metallic liquid and said electrolyte effective to move the interface of said liquids and to change the interfacial tension between said liquids to produce a voltage at said electrodes due to the electrocapillary effect, said means including means for sealing off an end of said envelope, a suspended mass responsive to vibrations to cause movement thereof for producing corresponding movement of said sealing means, and a material between said sealing means and one of said liquids for transmitting the force to the said one liquid.

2. An electrocapillary transducer as in claim 1, wherein said sealing means comprises a bellows which is directly acted upon by the vibrations of said mass.

3. An electrocapillary transducer as in claim 1, further comprising a spring for suspending the mass.

4. An electrocapillary transducer as in claim 2, further comprising means for adjusting the length of the spring.

5. An electrocapillary transducer as in claim 1, further comprising a lever arm pivotally mounted about a point, said mass engaging said lever arm at a point spaced from its pivot point to provide a mechanical advantage.

6. An electrocapillary transducer as in claim 5, further comprising means for adjusting the spacing between the pivot point and the point of engagement with the mass.

7. An electrocapillary transducer comprising an envelope including a tube portion having capillary transverse interior dimensions, a metallic liquid contained within said envelope and extending into said tube portion, a liquid electrolyte contained within said envelope and extending into said tube portion, said metallic liquid and said electrolyte being immiscible in each other and forming a single interface only in said capillary tube, electrode means respectively in electrical contact with said metallic liquid and said electrolyte, means responsive to a component of physical acceleration for applying a force across said metallic liquid and said electrolyte in response to a component of physical acceleration to move the interface of said liquids and to change the interfacial tension between said liquids to produce a voltage at said electrodes due to the electrocapillary effect.

8. An electrocapillary transducer as in claim 7, wherein said means responsive to the component of physical acceleration comprises a flexible membrane.

9. An electrocapillary transducer as in claim 7, wherein said means responsive to the component of physical acceleration comprises a spring member.

10. An electrocapillary transducer as in claim 7, further comprising means for converting the voltage produced at said electrodes into digital signals.

11. An electrocapillary transducer as in claim 7, wherein said envelope comprises a first tube containing said metallic liquid and a second tube containing said electrolyte, said capillary tube connecting said first and second tubes and said means responsive to the component of physical acceleration acting on the liquid in one of said first and second tubes.

12. An electrocapillary transducer as in claim 7 wherein said envelope includes a reservoir portion con taining one of said metallic and electrolyte liquids and a pair of tube portions of capillary transverse interior dimensions in communication therewith, said metallic liquid and said electrolyte extending into each of said tube portions to establish a respective single interface therein, said electrode means being in electrical contact with the metallic liquid and electrolyte in each of said tube portions, and said means responsive to said component of physical acceleration adapted to move the interface on each said tube portion.

13. An electrocapillary transducer as in claim 12 wherein said acceleration responsive means includes a part located in said reservoir means to act on the liquids therein.

14. An electrocapillary transducer as in claim 13 wherein said acceleration responsive means comprises a piston.

15. An electrocapillary transducer as in claim 7 wherein said capillary tube portion is generally vertical.

16. A transducer as in claim 15 wherein said interface lies in a generally horizontal plane.

17. A transducer as in claim 7 wherein said envelope has at least one portion extending generally vertically for holding said electrolyte and said liquid metal.

18. A transducer as in claim 17 wherein said capillary tube portion is generally vertical.

19. An electrocapillary transducer as in claim 7 wherein said means responsive to the component of physical acceleration comprises a movable piston.

Claims

1. An electrocapillary transducer comprising an envelope including a tube portion having capillary transverse interior dimensions, a metallic liquid contained within said envelope and extending into said tube portion, a liquid electrolyte contained within said envelope and extending into said tube portion, said metallic liquid and said electrolyte being immiscible in each other and forming a single interface only in said capillary tube, electrode means respectively in electrical contact with said metallic liquid and said electrolyte, means external of said envelope for applying a force across said metallic liquid and said electrolyte effective to move the interface of said liquids and to change the interfacial tension between said liquids to produce a voltage at said electrodes due to the electrocapillary effect, said means including means for sealing off an end of said envelope, a suspended mass responsive to vibrations to cause movement thereof for producing corresponding movement of said sealing means, and a material between said sealing means and one of said liquids for transmitting the force to the said one liquid.

12. An electrocapillary tRansducer as in claim 7 wherein said envelope includes a reservoir portion containing one of said metallic and electrolyte liquids and a pair of tube portions of capillary transverse interior dimensions in communication therewith, said metallic liquid and said electrolyte extending into each of said tube portions to establish a respective single interface therein, said electrode means being in electrical contact with the metallic liquid and electrolyte in each of said tube portions, and said means responsive to said component of physical acceleration adapted to move the interface on each said tube portion.