GB1566000A - Sample ejection systems - Google Patents

Description

(54) SAMPLE EJECTION SYSTEMS (71) We, COULTER ELECTRONICS LIMITED, a British Company of Coldharbour Lane, Harpenden, Hertfordshire, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to sample ejection systems.

The invention relates particularly, but not exclusively, to a non-diluting particle study device and more specifically to a device for ejecting a non-diluted specific minute amount of fluid sample containing particles into a flow stream leading to a sensing zone in a particle study device.

Heretofore, in the field of particle analysis and particle study, such as the study of red and white blood cells in a blood sample, it has been common practice to dilute the blood sample and then to pass portion of the diluted sample through a sensing zone in a particle study device. The blood is diluted because the normal human blood count is five million cells for cubic millimeter and it is only necessary to study or analyze one hundredth of that amount, namely, a volume of 0.01 cubic millimeters.

In studying a blood sample, the blood cells in a given amount of the sample are counted by passing a portion of the diluted blood sample through a sensing zone in a particle analyzing device. In this device, when a microscopic particle in suspension in a fluid electrolyte is passed through an electrical field of small dimensions approaching those of the particle, there will be a momentary change in the electrical impedance of the electrolyte in the ambit of the field. This change of impedance diverts some of the excitation energy into associated electrical circuitry, giving rise to an electrical signal. Such signal has been accepted as a reasonably accurate indication of the particle volume for most biological and industrial purposes.

One apparatus of the above type includes first and second vessels each containing a body of fluid electrolyte. The second vessel is smaller and is immersed in the electrolyte in the first vessel. An electrode extends into the electrolyte in each vessel and electric current flows between the electrode through an opening in the side wall of the second vessel, the opening consisting of a minute aperture.

Flow of liquid between the vessels is caused by applying vacuum to the second vessel.

Particles passing through the aperture from one body of electrolyte to the other body of electrolyte will change the impedance of the electrolyte contained within the aperture and this change in impedance is sensed by the electrodes. This change generates an electrical signal in the form of a particle pulse which is then counted by the electrical circuitry of the particle analyzing device.

When making a blood analysis a dilution of blood in electrolyte is placed in the first vessel. Then vacuum is applied to the second vessel to cause diluted blood to flow from the first vessel through the aperture into the second vessel for a specified period of time, usually the time required to pass a known aliquot of suspension.

The second vessel is filled with electrolyte, probably including prior dilutions.

To make a fairly accurate measurement of particle concentration, one must accurately measure or meter the amount of fluid which passes through the sensing zone during a period of time when the electrical circuitry of the device is operative. This can be accomplished by passing fluid through the sensing zone at a given flow rate for a specified period of time.

In most particle analyzing devices of the type noted, the metering is accomplished with a fluid metering apparatus.

Such metering apparatus includes a closed fluid system hydraulically connected to the second vessel. The closed fluid system includes a connection to a vacuum source and a mercury manometer. When operating the device, vacuum is applied to the closed fluid system to raise the mercury in the manometer and to draw some fluid sample into the second vessel. The connection to the vacuum source is then closed and a manometer, by reason of the mercury flowing downwardly to its original position, causes liquid to be drawn through the aperture and generates signals indicaitng the beginning and the end of an analytic run in a period during which an accurately metered volume of fluid is passed through the aperture. The metered volume of fluid is equal to the volume within the manometer between two electrodes.

It will be understood from the foregoing description of a particle analyzing device that it is necessary to dilute a quantity of blood, to make an accurate determination of dilution and to accurately meter the fluid flow through the minute aperture in order than an accurate count of blood cells can be made. A simpler way of making the particle analysis or study would be to pass a specific minute amount of undiluted blood through the minute aperture and thereby eliminate the manometer and diluter systems. A device for ejecting a specific minute amount of particle-containing fluid such as blood into the flow stream leading to a sensing zone in a particle analyzing device is shown in British Patent No. 1,388,096.

In the above noted patent circuitry is disclosed for operating the ejecting device.

The circuitry provides a predetermined amount of electrical energy to the device causing it to increase in temperature, expand and eject a specific amount of fluid.

The amount of energy provided is determined mathematically and, in the embodiment described therein, is the amount of energy necessary to raise the temperature of the device twenty degrees, a twenty degree rise causing a specific expansion and therefore an ejection of a specific amount of fluid.

Circuitry is described in United States Patent 3,973,196 which operates to raise the temperature of the device by a specific amount in excess of the device temperature at the start of the expansion process, and supplies whatever energy is necessary to raise the temperature the desired amount.

In the ejecting devices noted if sufficient thermal insulation is used to ensure that heat loss during a heating cycle is not excessive, an extended cool-off period is necessary. Extended cool-off periods are undesirable from an operational point of view, particularly in an automated system.

In systems where operating speed is important such as automated systems, it is desirable to have some means for providing a rapid cooling of the ejecting device.

The present invention provides a sample ejecting system comprising a sample ejector having means for receiving and storing temporarily an aliquot of liquid sample therein and a thermall expansible body disposed within said receiving and storing means, said body being capable of being heated and expanded to enable ejection from the ejector of a predetermined volume of said sample, and thermally conductive means coupled to said sample ejector and operable in a first mode to conduct heat from said ejector for cooling and contracting said expansible body.

Said thermally conductive means can comprise a heat dissipator for dissipating heat and thermal conduit connecting said sample ejector and said heat dissipator when said thermally conductive means is in said first mode for conducting heat from said sample ejector for cooling and contracting said expansible body.

The thermally expansible body can comprise an elastic jacket surrounding an expansible element which in turn surrounds a heating element for conducting heat therefrom and said thermal conduit can be coupled through said jacket and can contact the expansible element.

Said thermal conduit can have a first portion secured to the expansible body and a second portion secured to said heat dissipator, said first and second portions being coupled together when said thermally conductive means is in said first mode.

At least one of said first and second portions can be metallic.

Control means can be coupled to said thermal conduit and to said thermally expansible body to develop said first mode and at least a second mode, said control means being operative in said first mode to couple together said first and second portions and operative in said second mode to uncouple said first and second portions and to couple a signal to said thermally expansible body for heating said body.

Said heat dissipator can be a heat sink.

Said heat dissipator can be a thermoelectric device operative in said first mode to cool thermoelectrically for cooling and contracting said thermally expansible body.

Control means can be coupled to said thermal conduit and said thermally expansible body and can be operative to develop said first mode and at least a second mode, said control means being operative in said first mode to actuate said thermoelectric device to cool thermoelectrically for cooling and contracting said thermally expansible body and operative in said second mode to couple a signal to said thermally expansible body for heating said body.

Said sample ejector can have an input port, an output port and an ejection port, shutoff structure coupling said input port to a source of sample and said output port to a drain, said shutoff structure operative in a first position to allow sample to pass through said receiving and storing structure from said source to said drain, and operative in a second position to trap a volume of said sample, said thermally expansible body being operative in response to a control signal to heat and expand for ejecting a predetermined amount of said trapped sample, and control means can be coupled to said shutoff structure, said thermally expansible body and said thermally conductive means and operative to switch said shutoff structure between said first and second positions, to develop said control signal when said shutoff structure is in said second position, and to develop a first mode signal for operating said thermally conductive means in said first mode.

Said control means can be arranged to develop said first mode signal with said shutoff structure positioned in said second position.

Said control means can be further operative to switch said shutoff structure to a third position, said control means being operative to develop said first mode signal with said shutoff structure positioned in said third position.

Said sample ejecting device can further include a stopcock assembly having a stopcock valve rotatably mounted therein, said stopcock valve having said receiving and storing structure formed therein and said input port, drain port and ejection port formed therein and in communication with said receiving and storing structure, said assembly having said input and drain formed therein, said shutoff structure including said stopcock valve, said stopcock valve being rotatable to said first position for aligning said input and input port and drain and drain port for receiving and expelling said sample, said stopcock valve being rotatable to said second position for blocking said input and drain port and trapping said volume of sample in said accumulation chamber, and said thermal conduit can comprise a first portion mounted in said stopcock valve and coupled to said thermally expansible body and a second portion secured to said stopcock assembly and communicating with said heat dissipator.

Said control means can be arranged to develop said first mode signal with said shutoff structure positioned in said second position and said first and second portions of said thermal conduit can be coupled together when said shutoff structure is positioned in said second position.

A preferred embodiment of this invention will now be described by way of example with reference to the drawings accompanying this specification in which.

Figure 1 is a section view of a sample ejecting device and sensing zone structure; Figure 2 is a perspective view of the electrolyte flow assembly shown in Figure 1; Figure 3 is a block diagram of an entire improved particle study device showing the sample ejecting device and structure of the sensing zone as a block within the block diagram.

Figure 4 is a combined perspective view and block diagram of the sample ejecting system of this invention; Figure 5 is a section view of the sample ejecting device which includes the features of this invention; Figure 6 is a plan view of the sample ejecting device in Figure 4 and a portion of the control circuit.

Figure 7 is a block diagram of the control circuit used in the system shown in Figure 4; and Figure 8 is a waveform diagram of signals at various points in the block diagram of Figure 6.

The description with reference to Figures 1 to 3 is preliminary to the description with respect to the remaining Figures.

Figures 1 to 3 describe the construction and use of a sample ejecting device and the remaining Figures illustrate the embodying of the invention in such a device.

Referring to Figure 1, a stopcock assembly 10 includes a housing 12 formed from glass or other insulating material.

The housing includes a truncated cone shaped chamber 14. Pipes 16 and 18 are formed onto housing 12 and include a conduit 20 passing therethrough and connecting with chamber 14.

A stopcock valve 24 is fitted into chamber 14 and rotates therein. Stopcock valve 24 has a conduit 26 passing therethrough which connects with conduit 20 in pipes 16 and 18 when stopcock valve 24 is rotated to a first position. Conduit 26 connects with a chamber 28 formed substantially in the center of stopcock valve 24. A minute opening 30 is formed in sidewall 32 of stopcock valve 24 and connects with chamber 28 thereby providing three separate openings to chamber 28 in stopcock valve 24.

Positioned in chamber 28 of stopcock valve 24 is an expansive element 34 such as is shown and described in said British Patent 1,388,096. Expansive element 34 includes an elastic outer member 36 surrounding a thermal expansion element 37.

A resistor 38 is embedded in the thermal expansion element 37. Wires 40 secured to the terminals of resistor 38 pass through thermal expansion element 37 and elastic outer member 36 and extend through an aperture 42 formed in handle 44 of stopcock valve 24. Handle 44 is inserted into the end of chamber 28 after insertion of the expansive element 34 in order to seal the chamber from the external environment. After expansive element 34 has inserted, the aperture 42 is filled with a sealant 43. Wires 40 then are connected to contact terminals 46 on portion 48 of handle 44 in order to provide a convenient means of connecting expansive element 34 with the equipment with which it is associated.

The stopcock assembly 10 is positioned adjacent and bears against a ring shaped electrolyte flow assembly 52, which is shown in perspective in Figure 2. Electro lyte flow assembly 52 is formed from stain less steel, an effective noncorrosive conductive member, so as to eliminate the need for a separate electrode in this portion of the particle study device. The electrolyte flow assembly 52 includes a ring shaped housing member 54. A tube 56 is formed in the sidewall 58 of ring shaped housing member 54 and extends radially therefrom. Annular grooves 60 are formed at the corners of the inner surface 62 of housing member 54 and rings 64 and 66 are seated in these annular grooves 60.

The electrolyte flow assembly 52 is seated on a plate 70 formed from glass and forms a chamber 69 above plate 70.

A minute aperture 72 is formed in the center of plate 70 and a ruby or sapphire wafer 74 having a microscopic aperture therethrough is secured to plate 70 surrounding aperture 72 in order to form what is commonly known in the art as a Coulter aperture. An annular ring 71 is formed of glass, is positioned on and secured to the top surface of plate 70.

Plate 70 is seated on a cylindrically shaped housing 78, formed of glass or other insulating material and having cylindrical sidewalls 80 and a bottom wall 82. A conduit tube 84 is formed in the center of bottom wall 82 and extends downwardly perpendicular to the plane of bottom wall 82. The top edges of sidewall 80 have an annular groove 86 formed therein and an 0 ring 88 is seated in annular groove 86 in order to provide a seal between housing 78 and plate 70.

The entire assembly consisting of electrolyte flow assembly 52, plate 70 and cylindrical shaped housing 78 is held together via clamps 90. A second electrode 94 is positioned in the chamber 81 formed by sidewall 80 and bottom wall 82 of cylindrical shaped housing 78. A conductor 96 connects electrode 94 to the external particle analyzing apparatus in the same manner as conductor 98, secured to sidewall 58 of ring shaped housing 54 is connected to the particle analyzing apparatus.

In operation, handle 44 of stopcock valve 24 is turned to a first position, by an automatic control mechanism. In the first position, conduit 20 is connected directly to conduit 26 and chamber 28 allowing a sample of blood or some other particular laden matter to be analyzed to be entered into chamber 28. The sample of blood or other particulate matter may be forced into chamber 28 via suction drawing on conduit 20, or via pressure forcing the fluid into conduit 20 and chamber 28. When the sample has been entered into chamber 28, handle 44 is moved to its second position, turning stopcock valve 24 and breaking the connection between conduit 26 and conduit 20.If the chamber 28 is not in 10, if not presently in position, may be placed on electrolyte flow assembly 52 such as is shown in Figure 1 with 0 ring 66 forming the seal so as to prevent the escape of any electrolyte or sample diluted in the electrolyte.

If the chamber 28 in stopcock assembly 10 is filled while in position an electrolyte flow assembly 52, all fluid connections to chambers 69 and 81 therein including connections not shown such as, for example, connections to provide fluid to flush the chambers, must be closed off by appropriate valves creating a pressure differential to prevent flow through aperture 30 into chamber 28. This forces chamber 28 to be filled only with the sample of blood via codnuit 20. If the chamber 28 is not in position on electrolyte flow assembly 52 when it is filled, opening 30 can be plugged with an appropriate device to prevent entry of air into chamber 28 via opening 30. Alternatively, if the sample is forced into chamber 28 slowly the low pressure will not create sufficient suction to draw air into chamber 28 through opening 30, since surface tension provides a fairly effective barrier against flow through a microscopic passageway which is wet on one side only.

Electrolyte is allowed to enter the electrolyte flow assembly 52 via tube 56 and fill the center area of electrolyte flow assembly 52. Trapped air may be avoided by filling chambers 69 and 81 before affix ing stopcock valve 24. The electrolyte is forced to flow around annular ring 71 causing the fluid to flow past opening 30.

The electrolyte will pass through aperture 72 in plate 70 filling the cavity formed by cylindrical shaped housing 78 and providing a current path between the electrode formed from ring shaped housing member 54 and conductor 98 and electrode 94 and conductor 96.

The electrodes 46 in portion 48 of handle 44 are connected to the control circuit previously noted which will be explained in greater detail in a subsequent portion hereof. The control circuit generates a control signal which may be a voltage, or current, that is coupled to the electrodes 46 and, via conductors 40 to resistor 38 in expansive element 34. The heat generated by resistor 38 will cause thermal expansion element 37 to expand and force a minute, precise quantity of sample from chamber 28 through aperture 30. This minute, precise amount of sample will proceed directly to the aperture surrounded by the electrolyte in electrolyte flow assembly 52.The sample particles in electrolyte solution in electrolyte flow assembly 52 will pass through the aperture in wafer 74 causing a change in impedance between electrode 94 and the electrode formed by housing member 54 of electrolyte flow assembly 52. This change in impedance will be sensed by the particle analyzing device for counting the particles and analyzing various characteristics of the particles.

Referring now to Figure 3, the entire apparatus shown in Figure 1, consisting of stopcock assembly 10, ring shaped flow assembly 52 aperture plate 70, and cylindrically shaped housing 78 is shown generally as 100 and will hereinafter be referred to as sensing zone and sample metering device 100. A particle analyzer 102 is coupled to sensing zone and sample metering device 100 via conductors 96 and 98. The terminations of conductors 96 and 98 are shown in greater detail in Figure 1. Particle analyzer 102 supplies electrical excitation to electrodes 94 and 54 in Figure 1 via conductors 96 and 98. The passage of particles through the sensing zone in sensing zone and sample metering device 100 will cause a modulation of the electrical excitation which will be detected by particle analyzer 102 and can be used for counting and sizing the particles.

A control circuit 104 is shown as being coupled to sensing zone and sample metering device 100. Control conduit 104 includes circuitry for developing a control signal which is coupled via conductor 106 to terminals 46 on handle portion 48 of stopcock valve 24. This control signal will cause resistor 38 in expansive element 34 to heat up and cause an expansion of the thermal expansion element 37. The control signal is coupled to particle analyzer 102 via conductor 105 for initiating operation thereof when the sample is ejected. Particle analyzer 102 includes a pulse rate meter which develops a rate signal in response to a reduction in the pulse rate, thus indicating the ejection and counting of substantially all particles in the sample.

The rate signal stops operation of analyzer 102. Control circuit 104 will operate in response to the rate signal to either terminate the control signal or initiate another operation cycle immediately or after a timed interval.

Pipe 84 shown in Figure 1, couples sensing zone and sample metering device 100 to a drip chamber 108. Drip chamber 108 is of a known type. The output of drip chamber 108 is coupled to the input of a pump 107 and the output of pump 107 is coupled to a filter 109. The output of filter 109 is coupled to pipe 16.

In operation, the particle laden diluent electrolyte, which has passed through the sensing zone and sample metering device 100, passes via pipe 18 to drip chamber 108.

Drip chamber 108 breaks any electrical connection caused by the electrolyte diluent thus preventing the short-circuiting of signals away from the input of the particle analyzer 102. The electrolyte diluent passing through drip chamber 108 is pumped by pump 107 to filter 109 which removes the particulate matter. The output of filter 109 is, therefore, filtered diluent electrolyte which is pumped to pipette 16 and is reused in the operaion of the sample metering device.

Referring to Figures 4 and 5, an embodi- ment of the invention in a stopcock assembly similar to that shown in Figure 1 will now be described. Stopcock assembly 110 includes a housing 112 formed from glass. The housing includes a truncated cone shaped chamber 114. Pipes 116 and 118 are formed into housing 112 and include a conduit 120 passing therethrough and connecting with the chamber 114.

These pipes constitute input and output ports respectively.

A stopcock valve 124 is fitted into chamber 114 and rotates therein. Stopcock valve 124 has a conduit 126 passing therethrough which connects with conduit 120 when stopcock valve 124 is rotated to a first position. Conduit 126 connects with sample accumulation chamber 128 formed substantially in the center of stopcock valve 124. A minute opening 130 is formed in sidewall 132 of stopcock valve 124 and connects with chamber 128 thereby providing three separate openings to cham ber 128 in stopcock valve 124.

Positioned in chamber 128 of stopcock valve 124 is an expansive element 134 such as is shown and described in British Patent 1,388,096. Expansive element 134 includes an elastic outer member 136 surrounding a thermal expansion element 137. A resistor 138 and a thermistor 139 are embedded in the thermal expansion element 137. A pair of wires 140 secured to the terminals of resistor 138, and a pair of wires 141 secured to the terminals of thermistor 139 pass through thermal expansion element 137 and elastic outer member 136 and extend through an aperture 142 formed in handle 144. Wires 140 and 141 are connected to a control circuit 146.

A thermoelectric module 150, oftentimes referred to as a "Peltier junction" is shown secured to a heavy metal plate 151 which is secured to the outer wall of housing 112. Secured to thermoelectric module 150 is a heat dissipation structure 152 which takes the form of a number of metallic fins secured to a metallic base.

Heat dissipation structure 152 is more commonly referred to as a heat sink. It may or may not have cooling fins as shown.

Thermoelectric module 150 is electrically actuated by control circuit 146 and develops a coId surface by use of a thermoelectric process. Plate 151 evenly conducts heat coupled thereto to the entire cold surface. Heat is also generated during the process and the heat is dissipated by heat sink 152.

One or more openings 154 are formed at specific locations in housing 112 and extend from the outer surface of housing 112 to the surface defining chamber 114.

In Figure 5 only a single opening is shown.

A spring finger 156 is seated in each such opening 154 and is secured at its one end to plate 151. Each finger extends through opening 154 and slightly into housing chamber 114 and is formed from a suitable highly thermally conductive material such as beryllium copper.

One or more heat conductors 158 extend radially in stopcock valve 124. Each heat conductor 158 passes into thermal expansion element 137 and extends through elastic outer member 136 of expansive element 134 terminating at a plug 160 which extends to the edge of stopcock valve 124 that seats in housing chamber 114. Heat conductor 158 and plug 160 are formed from a highly thermally conductive material which may be metallic or may be a non-metallic highly conductive material such as, for example, beryllium oxide. It must be chosen to resist wear due to friction against thermal contact finger 156.

In operation, handle 144 of stopcock valve 124 is rotated to a first position, either manually or via an automatic control mechanism. In the first position, conduit 120 is connected directly to conduit 126 and chamber 128 allowing a fluid sample such as blood to be entered into chamber 128. The sample is forced into chamber 128 by a suction drawing on conduit 120 or by a pressure forcing the fluid into conduit 120 and chamber 128.

When the sample has been entered into chamber 128, handle 144 is rotated to a second, center position turning stopcock valve 124 and breaking the connection between conduit 126 and conduit 120. In this second position, an aliquot of sample is trapped in chamber 128. Energy is applied to expansive element 134 while stopcock valve 124 is in this second position in order to heat and expand element 134 and eject a predetermined quantity of sample through aperture 130. When expansive element 134 has expanded completely so that the desired amount of sample has been ejected through opening 130, handle 144 is rotated to a third position.In this third position uach heat conductor 158 and plug 160 is rotated into contact with a spring finger 156 thus providing a highly thermally conductive path between the heated thermal expansion element 137 and the plate 151, thermoelectric module 150 and heat sink 152.

This connection and the actuation of thermoelectric module 150 results in a rapid dissipation of the heat developed in thermal expansion element 137, and thus a rapid contraction of expansion element 137 back to its original or normal size.

When the cooling process is completed, and it is desired to again initiate another operating cycle, handle 144 is rotated back to the first position.

Referring now to Figure 6, one mechanism for rotating handle 144 of stopcock valve 124 is shown in detail. A pivot mechanism 162 is shown positioned adjacent handle 144 and includes a mounting plate 164 which may be secured to a wall or to the same structure which holds and supports stopcock assembly 110. A fork shaped structure 166 includes a handle portion 168 and two finger portions 170 and 172 which extend toward the opposite ends of handle 144 from an end of handle portion 168. A spring 174 extends between mounting plate 164 and the end of handle portion 168 to which fingers 170 and 172 are attached. The spring exerts a pressure . against fork shaped member 166 and mounting plate 164 causing fingers 170 and 172 to bear against handle 144. This pressure causes handle 144 to be held in its second or center position.

Solenoids 176 and 178 are positioned adjacent to the mechanism 162 and also are mounted thereto. These solenoids are considered to be a part of control circuit 146 as will be explained in greater detail hereafter. Control fingers 180 and 182 are seated in solenoids 176 and 178 respectively and extend to a point adjacent the opposite ends of handle 144. When solenoid 176 is operated it will draw control finger 180 into solenoid 176. As control finger 180 is drawn into solenoid 176 the end adjacent handle 144 will contact handle 144 causing handle 144 to rotate in a counter-clockwise direction. When control finger 180 completes its travel into solenoid 176, handle 144 will be rotated in a counter-clockwise direction to its first posi fion whereby conduit 120 in pipes 116 and 118 is connected to conduit 126.Upon deactivation of solenoid 176, control finger 180 will return to its normal or extended position by action of spring 184, and handle 144 will return to its second or center position by action of the pivot mechanism 162.

Solenoid 178 operates in a manner similar to solenoid 176 and when actuated will draw control finger 182 into the solenoid 178. As control finger 182 is drawn into solenoid 178, the end adjacent handle 144 will contact handle 144 causing the handle to rotate in a clockwise direction.

When control finger 182 is drawn into solneoid 178 the maximum distance, handle 144 will be rotated to its third position.

Upon deactivation of solenoid 178, control finger 182 will return to its outermost position by the spring action of spring 186 and handle 144 will return to its second position by operation of pivot mechanism 162.

Referring now to Figures 7 and 8, the clock diagram and timing waveform diagrams for control circuit 146 are shown.

In order to initiate operation, start switch 200 is actuated coupling a start pulse, shown in waveform A of Figure 7, to one input of AND gate 202. The second input of AND gate 202 is an inverted input, and for the purpose of explaining this operation assume that the input signal at the second input is a low state or zero level signal so that with the receipt of the start pulse from start switch 200 AND gate 202 will develop a high state signal which is coupled to a monostable multivibrator 204. Monostable multivibrator 204 commonly known as a one-shot, will develop a high state or one level signal, shown in waveform B of Figure 8, in response to the signal received from AND gate 202. The high state signal developed by monostable multivibrator 204 is coupled to sample solenoid 176, a trailing edge detector (T.E.D.) 206 and leading edge detector (L.E.D.) 208.

Sample solenoid 176 actuates in response to the signal from monostable multivibrator 204 causing arm 180, shown in Figure 6, to be drawn into the solenoid and handle 144 to be rotated in the first position.

During the interval that monostable multivibrator 204 develops this high state signal, and while stopcock valve 124 is in the first position, the fluid sample path is completed and fluid sample is passed through conduit 120 and pipes 116 and 118 into conduit 126 and chamber 128 in stopcock assembly 110. When the high state signal developed by monostable multivibrator 204 terminates sample solenoid 176 is deactivated and handle 144 returns to its second position.

Leading edge detector 208 develops a pulse shown in waveform C of Figure 8, in response to the leading edge of the high state signal developed by monostable multivibrator 204. The pulse developed by leading edge detector 208 is coupled to the reset input 210 of a bistable multivibrator 212 causing bistable multivibrator 212 to return or reset as shown in waveform D of Figure 8. This allows deactivation of solenoid 178. It is to be understood that deactivation of solenoid 178 and activation of solenoid 176 occurs substantially simultaneously.

The trailing edge of the high state signal developed by monostable multivibrator 204 is detected by trailing edge detector 206 which develops a pulse in response thereto shown in waveform E of Figure 8. The pulse developed by trailing edge detector 206 is coupled to a monostable multivibrator 214 and to the reset input 216 of a counter 218. The pulse coupled to reset input of counter 218 causes the counter to reset to a zero count. The pulse coupled to monostable multivibrator 214 causes it to change states and develop a high level signal shown in waveform F of Figure 8. Monostable multivibrator 214 is employed simply to provide a fixed amount of operational delay to insure that any undesired transients have subsided.

The high state signal developed by monostable multivibrator 214 is coupled to a trailing edge detector 120 which develops a pulse shown in waveform G of Figure 8 in response to the trailing edge of the high state signal developed by monostable multivibrator 214.

The pulse developed by trailing edge detector 220 is coupled to monostable multivibrator 222 and to the " set " input 224 of a bistable multivibrator 226, more commonly known as a flip-flop. Monostable multivibrator 222 will develop a high state signal in response to the pulse from trailing edge detector 220 which is shown in waveform H of Figure 8. This high state signal is coupled to the coil of a relay 228 causing contacts 230 to close. Contacts 230 form the start contacts for the expansive element heating circuit 232. Expansive element heating circuit 232 can be a circuit such as is shown in British Patent No. 1,388,096.

During the time the monostable multivibrator 222 develops a high state signal, expansive element heating circuit 232 supplies energy to and heats the thermal expansion element 137 in expansive element 134 in stopcock assembly 110. The temperature of expansion element 137 is shown in waveform N by a solid line and causes expansive element 134 to expand and eject a specific predetermined amount of fluid sample through the minute aperture 130 shown in Figure 4.

Assuming that the sample is blood, and further assuming the stopcock assembly 110 is attached to a particle study device, represented in Figure 7 by a block 234, such as is shown in greater detail in Figure 3, the blood cells in the sample will be detected as they pass through a microscopic aperture in the particle study device 234. Particle study device 234 will develop a particle pulse in response to each detected particle. While the sample is being ejected from chamber 128 and for some short period thereafter, a substantial number of particles will pass through particle study device 234 and will be detected. Before and after ejection of the sample from chamber 128 very few particles will pass through particle study device 134 and be detected.

As noted previously, the pulse developed by trailing edge detector 220, shown by waveform G in Figure 9, is coupled to "set" input 224 of bistable multivibrator 226. This pulse will cause bistable multivibrator 226 to change states and develop a high state signal which is coupled by conductor 236 to one input of AND gate 238. This high state signal is shown in waveform J of Figure 8. With a high state signal at the one input of AND gate 238, each high state signal developed at the second input of AND gate 238 will cause the output of the AND gate 238 to change to a high state signal. Each high state signal developed at the output of AND gate 238 will actuate counter 218 to increase its count by one. AND gate 238 is receiving a high state signal at conductor 236 while expansive element 134 is receiving energy from heating circuit 232.

Consequently, the particles being expelled from chamber 128 and passed to particle study device 234 will cause particle study device 234 to develop particle pulses, and each particle pulse develops a high state signal that is coupled from particle study device 234 to the second input of AND gate 238 causing the counter to count each detected particle pulse.

The particle pulses developed by particle study device 234 are also coupled to a ratemeter 240. Ratemeter 240 develops a DC voltage which is proportional in amplitude to the repetition rate of pulses received by ratemeter 240. The voltage developed by ratemeter 240 is coupled to a threshold circuit 241. When the particle pulses developed occur at less than a particular repetition rate, thus indicating that all of the blood cells in the sample ejected from chamber 128 have passed through particle study device 234, the signal developed by ratemeter 240 will fall below a threshold level causing threshold circuit 241 to develop the upper level threshold signal shown in waveform K of Figure 8, which is coupled to the reset input 242 of bistable multivibrator 226 and to a leading edge detector 244.The threshold signal coupled to the reset input 242 of bistable multivibrator 226 will reset multivibrator 226 as shown in waveform J thus inhibiting AND gate 238 and further inhibiting any additional count by counter 218.

The threshold signal coupled to leading edge detector 244 will cause detector 244 to develop a pulse, shown in waveform L of Figure 8, which is coupled to the "set" input 246 of bistable multivibrator 212 and to a monostable multivibrator 248. Bistable multivibrator 212 is in a reset state at the time of receipt of the pulse at set input 246 so that bistable multivibrator will change states in response to this pulse and develop a high state signal. The high state signal is coupled to cooling solenoid 178 and to an inverted input 250 of OR gate 252.

The high state signal developed by bi- stable multivibrator 212 will cause solenoid 178 to actuate thus rotating handle 144 and stopcock valve 124 to the third position wherein heat conductor 158 and fingers 156 shown in Figure 5 are connected. The pulse of leading edge detector 244 coupled to monostable 248 causes monostable 248 to change states and develop a high state signal shown in waveform M which is coupled to thermoelectric module 150 and to the second input 254 of OR gate 250.

Thermoelectric module 150 operates in response to the monostable signal to begin cooling and the temperature of its coldsurface is represented by the dashed line waveform in waveform N of Figure 8.

The rapid cooling produced by thermoelectric module 150 and the conduction of heat generated by the module 150 away from the assembly by way of heat sink 152 causes a rapid cooling of expansive element 134. The time period during which monostable multivibrator 248 develops a high state signal is selected so that thermoelectric module 150 operates for a period of time sufficient for the expansive element 134 to cool once again to approximately ambient temperature as shown by the solid waveform N of Figure 8. Hence, its volume returns approximately to its normal value. If it is not returned exactly to its original temperature, the thermistor 139 and associated circuitry will compensate.

At the termination of the high state signal developed by monostable multivibrator 248 the output of OR gate 252 will change from a high state to a low state signal. This low state signal is coupled through delay line 256 where it is delayed slightly. Delay line 256 is employed in order to prevent the inhibiting of the start function upon operation of start switch 200 by the possible instantaneous response of the entire control circuit. The output of delay line 256 is coupled to the second or inverted input of AND gate 202. With a low state of zero level signal coupled to this inverted input AND gate 202 will once again be able to develop a high state signal at its output in response to actuation of start switch 200.

Upon initiation of the next operating cycle by actuation of switch 200 the operating cycle described previously will be repeated. It should be noted, however, that until the second operating cycle is repeated, stopcock valve 124 is maintained in its third position by cooling solenoid 178. When bistable multivibrator 212 is reset, after the initiation of a new operating cycle, cooling solenoid 178 is deactivated as shown in waveform D, returning stopcock valve 124 to its second position and simultaneously solenoid 176 moves the valve to its first position.

WHAT WE CLAIM IS: - 1. A sample ejecting system comprising a sample ejector having means for receiving and storing temporarily an aliquot of liquid sample therein and a thermally expansible body disposed within said receiving and storing means, said body being capable of being heated and expanded to enable ejection from the ejector of a predetermined volume of said sample, and thermally conductive means coupled to said sample ejector and operable in a first mode to conduct heat from said ejector for cooling and contracting said expansible body.

2. A sample ejecting system as claimed in claim 1, wherein said thermally conductive means comprises a heat dissipator for dissipating heat and thermal conduit connecting said sample ejector and said heat dissipator when said thermally conductive means is in said first mode for conducting heat from said sample ejector for cooling and contracting said expansible body.

3. A sample ejecting system as claimed in claim 2, wherein the thermally expanssible body comprises an elastic jacket surrounding an expansible element which in turn surrounds a heating element for conducting heat therefrom and said thermal conduit is coupled through said jacket and contacts the expansible element.

4. A sample ejecting system as claimed in any preceding claim, wherein said thermal conduit has a first portion secured to the expansible body and a second portion secured to said heat dissipator, said first and second portion being coupled together when said thermally conductive means is in said first mode.

5. A sample ejecting system as claimed in claim 4, wherein at least one of said first and second portions is metallic.

6. A sample ejecting system as claimed in claims 4 or 5, wherein control means are coupled to said thermal conduit and to said thermally expansible body to develop said first mode and at least a second mode, said control means being operative in said first mode to couple together said first and second portions and operative in said second mode to uncouple said first and second portions and to couple a signal to said thermally expansible body for heating said body.

7. A sample ejecting system as claimed in any of claims 2 to 6, wherein said heat dissipator is a heat sink.

8. A sample ejecting system as claimed in any of claims 2 to 6, wherein said heat dissipator is a thermoelectric device operative in said first mode to cool thermoelectrically for cooling and contracting said thermally expansible body.

9. A - sample ejecting system as claimed in claim 8; wherein control means or, with regard to claim 6, said control means are coupled to said thermal conduit and said thermally expansible body and operative to develop said first mode and at least a second mode, said control means being operative in said first mode to actuate said thermoelectric device to cool thermoelectrically for cooling and contracting said thermally expansible body and operative in said second mode to couple a signal to said thermally expansible body for heating said body.

10. A sample ejecting system as claimed in claim 2 or 3, wherein said sample ejector has an input port, an output port and and ejection port, shutoff structure coupling said input port to a source of sample and said output port to a drain,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (17)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   134. The time period during which monostable multivibrator 248 develops a high state signal is selected so that thermoelectric module 150 operates for a period of time sufficient for the expansive element 134 to cool once again to approximately ambient temperature as shown by the solid waveform N of Figure 8. Hence, its volume returns approximately to its normal value. If it is not returned exactly to its original temperature, the thermistor 139 and associated circuitry will compensate.

   At the termination of the high state signal developed by monostable multivibrator 248 the output of OR gate 252 will change from a high state to a low state signal. This low state signal is coupled through delay line 256 where it is delayed slightly. Delay line 256 is employed in order to prevent the inhibiting of the start function upon operation of start switch 200 by the possible instantaneous response of the entire control circuit. The output of delay line 256 is coupled to the second or inverted input of AND gate 202. With a low state of zero level signal coupled to this inverted input AND gate 202 will once again be able to develop a high state signal at its output in response to actuation of start switch 200.

   Upon initiation of the next operating cycle by actuation of switch 200 the operating cycle described previously will be repeated. It should be noted, however, that until the second operating cycle is repeated, stopcock valve 124 is maintained in its third position by cooling solenoid 178. When bistable multivibrator 212 is reset, after the initiation of a new operating cycle, cooling solenoid 178 is deactivated as shown in waveform D, returning stopcock valve 124 to its second position and simultaneously solenoid 176 moves the valve to its first position.

   WHAT WE CLAIM IS: - 1. A sample ejecting system comprising a sample ejector having means for receiving and storing temporarily an aliquot of liquid sample therein and a thermally expansible body disposed within said receiving and storing means, said body being capable of being heated and expanded to enable ejection from the ejector of a predetermined volume of said sample, and thermally conductive means coupled to said sample ejector and operable in a first mode to conduct heat from said ejector for cooling and contracting said expansible body.
2. 2. A sample ejecting system as claimed in claim 1, wherein said thermally conductive means comprises a heat dissipator for dissipating heat and thermal conduit connecting said sample ejector and said heat dissipator when said thermally conductive means is in said first mode for conducting heat from said sample ejector for cooling and contracting said expansible body.
3. 3. A sample ejecting system as claimed in claim 2, wherein the thermally expanssible body comprises an elastic jacket surrounding an expansible element which in turn surrounds a heating element for conducting heat therefrom and said thermal conduit is coupled through said jacket and contacts the expansible element.
4. 4. A sample ejecting system as claimed in any preceding claim, wherein said thermal conduit has a first portion secured to the expansible body and a second portion secured to said heat dissipator, said first and second portion being coupled together when said thermally conductive means is in said first mode.
5. 5. A sample ejecting system as claimed in claim 4, wherein at least one of said first and second portions is metallic.
6. 6. A sample ejecting system as claimed in claims 4 or 5, wherein control means are coupled to said thermal conduit and to said thermally expansible body to develop said first mode and at least a second mode, said control means being operative in said first mode to couple together said first and second portions and operative in said second mode to uncouple said first and second portions and to couple a signal to said thermally expansible body for heating said body.
7. 7. A sample ejecting system as claimed in any of claims 2 to 6, wherein said heat dissipator is a heat sink.
8. 8. A sample ejecting system as claimed in any of claims 2 to 6, wherein said heat dissipator is a thermoelectric device operative in said first mode to cool thermoelectrically for cooling and contracting said thermally expansible body.
9. 9. A - sample ejecting system as claimed in claim 8; wherein control means or, with regard to claim 6, said control means are coupled to said thermal conduit and said thermally expansible body and operative to develop said first mode and at least a second mode, said control means being operative in said first mode to actuate said thermoelectric device to cool thermoelectrically for cooling and contracting said thermally expansible body and operative in said second mode to couple a signal to said thermally expansible body for heating said body.
10. 10. A sample ejecting system as claimed in claim 2 or 3, wherein said sample ejector has an input port, an output port and and ejection port, shutoff structure coupling said input port to a source of sample and said output port to a drain,

    said shutoff structure operative in a first position to allow sample to pass through said receiving and storing structure from said source to said drain, and operative in a second position to trap a volume of said sample, said thermally expansible body being operative in response to a control signal to heat and expand for ejecting a predetermined amount of said trapped sample, and wherein control means are coupled to said shutoff structure, said thermally expansible body and said thermally conductive means and operative to switch said shutoff structure between said first and second positions, to develop said control signal when said shutoff structure is in said second position, and to develop a first mode signal for operating said thermally conductive means in said first mode.
11. 11. A sample ejecting system as claimed in claim 10, wherein said control means is arranged to develop said first mode signal with said shutoff structure positioned in said second position.
12. 12. A sample ejecting system as claimed in claim 10 or 11, wherein said control means is further operative to switch said shutoff structure to a third position, said control means being operative to develop said first mode signal with said shutoff structure positioned in said third position.
13. 13. A system as claimed in claim 10, wherein said sample ejecting device further includes a stop cock assembly having a stopcock valve rotatably mounted therein, said stopcock valve having said receiving and storing structure formed therein and said input port, drain port and ejection port formed therein and in communication with said receiving and storing structure, said assembly having said input and drain formed therein, said shutoff structure including said stopcock valve, said stopcock valve being rotatable to said first position for aligning said input and input port and drain and drain port for receiving and expelling said sample, said stopcock valve being rotatable to said second position for blocking said input and drain port and trapping said volume of sample in said accumulation chamber, and wherein said thermal conduit comprises a first portion mounted in said stopcock valve and coupled to said thermally expansible body and a second portion secured to said stopcock assembly and communicating with said heat dissipator.
14. 14. A sample ejecting system as claimed in claim 13, wherein said control means is arranged to develop said first mode signal with said shutoff structure positioned in said second position and said first and second portions of said thermal conduit are coupled together when said shutoff structure is positioned in said second position.
15. 15. A sample ejecting system as claimed in any preceding claim and substantially as described with reference to the accompanying drawings.
16. 16. A sample ejecting system comprising a sample ejecting device substantially as herein described with reference to and as illustrated by Figure 5 of the accompanying drawings.
17. 17. A sample ejecting system as claimed in claim 16 and including control means substantially as herein described with reference to and as illustrated by Figures 4, 6 and 7 of the accompanying drawings.