Patent Publication Number: US-2017363571-A1

Title: Electrochemical testing system

Description:
TECHNICAL FIELD 
     The present invention relates generally to electrochemical testing systems, and in particular to systems where fluid or other media is brought into contact with material to be tested and the electrochemical properties of that material are then measured by instrumentation. 
     BACKGROUND OF INVENTION 
     Current high throughput electrochemical testing apparatus rely upon multiplexing traditional potentiostat/galvanostat equipment to bulky electrochemical cells, or utilise costly multi-channel potentiostat/galvanostats. This approach has a number of drawbacks, including cost, time taken to perform the electrochemical testing and the inevitable wastage of large volumes of liquid. Notably, existing apparatus require multiple reference electrodes, glass testing cells and counter electrodes to be purchased. 
     It would be desirable to provide an electrochemical testing system that permits high throughput studies which are capable of characterising complex electrochemical interactions over a large number of separate experiments. It would also be desirable to provide an electrochemical testing system that ameliorates or overcomes one or more disadvantages of known electrochemical testing apparatus and methodologies. 
     SUMMARY OF INVENTION 
     One aspect of the present invention provides an electrochemical testing system, including: a test board including a plurality of testing wells, each well including a first well portion for holding a workpiece to be tested and bringing a first surface of the workpiece into contact with a separate working electrode lead for each testing well, a second well portion for holding a testing media and bringing a second surface of the workpiece into contact with the testing media, and a sealing mechanism for preventing contact of the testing media and the first surface of the workpiece; a media delivery system for selectively delivering the testing media into the second well portion; at least one sensing head for securing one or more electrochemical sensing elements at least one of which is adapted to form part of an electrochemical circuit with the testing media, workpiece and working electrode lead for each testing well, each testing well being electrically and physically isolated from other testing wells; testing apparatus for measuring electrochemical and/or chemical properties from the electrochemical circuit; and a motion control system for controlling relative movement of the sensing head and the plurality of testing wells so that the one or more sensing elements are selectively brought into contact with the testing media in the testing well of a selected workpiece to be tested. 
     The electrochemical testing system of the present invention enables multiple tests to be performed sequentially or in parallel and under the same environmental conditions through isolating (physically and electrically) the testing wells, thus forming multiple individually addressable electrochemical circuits to the respective workpieces, thereby increasing throughput and reducing systematic errors compared to conventional electrochemical testing systems. 
     Preferably, the testing apparatus measures the electrochemical properties of the workpiece or any of the substituent components that comprise the electrochemical circuit. 
     The workpiece is preferably selected from a group consisting of: manufactured products, natural products, scientific or research grade material(s)/sample(s), metal(s), alloy(s), textiles (natural and synthetic, including e-textiles), coatings/coated materials, nanomaterials, carbaceous materials, ceramic materials, composite materials, polymers, polymer blends, specialist glasses, metallic glasses, electroactive materials; or generally any electrochemically active material, One of the preferred embodiments uses a chemically “inert” (with respect to the reactivity of the media) material (e.g. Pt, Au, etc) as the workpiece, in order to electrochemically assess the testing media or electrolyte solution, finding utility in battery electrolyte formulation and similar media optimisation tasks. 
     Typical workpiece examples and their preferable applications may include one or more of the following: metal and alloy plates for the purposes of quality assurance (QA) and quality control (QC), screening corrosion inhibiting compounds and measuring their efficacy, or to screen the suitability of a given metal/alloy for a particular environmental extreme (e.g. in contact with acidic waste water); coated materials to assess the integrity of the coating or a screening method useful in the development of new coatings and formulations; battery electrode materials for QA/QC, screening of new electrode materials, assessment of electrolyte formulations to determine suitability and compatibility with electrode materials; for the assessment of electronic components which utilise electroactive or semiconducting materials in their construction, including but not limited to: capacitors, supercapacitors, ultracapacitors, batteries, solar cells, light dependant resistors, photodiodes, light emitting diodes and others known to those skilled in the art; testing and analysis of natural products such as those deemed to be of commercial or scientific importance; for the assessment, discovery and to inform the refinement of polymer(s) or polymer blends; testing and development of textile and related materials/products. It will be appreciated by those skilled in the art that these examples are by no means exhaustive, and that any material which can be electrochemically or non-electrochemically (as defined within this document) analysed can form part or the whole workpiece. 
     In one or more embodiments, the first well portion includes a body including a recess for receiving the workpiece and an opening in the body through which the working electrode lead passes to make contact with the first surface of the workpiece. 
     In one or more embodiments, the sealing mechanism includes a mechanical seal for location between the second surface of the workpiece and the second well portion and co-operating engagement members to cause the workpiece and the second well portion to bear against each other. 
     In one or more embodiments, the cooperating engagement members pass through aligned hole openings respectively in the first and second well portions. In other embodiments, the cooperating engagement members act to clamp or crimp surfaces of the first and second well portions together. 
     In one or more embodiments, the mechanical seals of the plurality of testing wells are unitary. 
     In one or more embodiments, one or both of the first well portions and the second well portions of the plurality of testing wells are unitary. 
     In one or more embodiments, the second well portion is formed from a chemically stable, electrically and ionically and/or non-conductive insulating material. 
     In one or more embodiments, the electrochemical sensing elements include one or more of a counter electrode, a reference electrode and a test probe. 
     In one or more embodiments, the test probe(s) is any one of a pH sensor or other ion-selective sensor/probe, a spectroscopic/hyperspectral measurement system/probe or an optical sensor. 
     In one or more embodiments, the at least one sensing head is adapted to secure one or more non-electrochemical sensing elements to perform non-electrochemical testing. Non-electrochemical testing is preferably testing of the material properties of the components making up the electrochemical circuit. Examples of non-electrochemical sensing elements include a spectroscopic/hyperspectral measurement system/probe or an optical sensor. 
     In one or more embodiments, the media delivery system includes media delivery tubing running between one or more media storage units and one or more media delivery output nozzles, and one or more operable pump units to selectively cause delivery of the media along the tubing and out of the nozzles. 
     In one or more embodiments, the media includes one or more of liquids, gel or solid. The media is preferably an electrolyte which may comprise one or more of the following: water, polar solvents, organic solvents, ionic liquids, corrosion inhibitors, stabilisation agents. 
     In one or more embodiments, the media delivery system is adapted to handle volumes of reagents/liquid/gels in the range of 1 nL to 1 L or more. More preferably, the media delivery system is adapted to handle volumes in the range 5 nL to 1000 ml, more preferably 1 ml to 500 ml, even more preferably 5 ml to 200 ml; and even more preferably 10 ml to 100 ml. The exact volumes used may depend upon the properties being tested. 
     In one or more embodiments, the one or more media delivery output nozzles are mounted to the sensing head. 
     In one or more embodiments, the electrical testing apparatus includes at least one electrical instrument having inputs connected to the working electrode lead and one or more of the sensing elements, and an output connected to measurement recording apparatus. 
     In one or more embodiments, the electrical testing apparatus further includes circuitry for connecting the working electrode of a selected testing well to the electrochemical measurement circuit. 
     In one or more embodiments, the motion control system includes a drive mechanism for driving one or both of the plurality of testing wells and sensing head along three orthogonal axes. 
     In one or more embodiments, the motion control system further includes a programmable controller configured for the operation of the drive mechanism and the electrical testing apparatus. 
     In one or more embodiments, the programmable controller is further configured to control operation of the media delivery system. 
     In one or more embodiments, the programmable controller is configured to execute a predetermined sequence of testing and/or calibration steps on workpieces held in one or more of the testing wells. 
     Another aspect of the invention provides a testing board for use with an electrochemical testing system as described above, the testing board including a plurality of testing wells, each well including 
     a first well portion for holding a workpiece to be tested and bringing a first surface of the workpiece into contact with a working electrode lead, 
     a second well portion for holding a testing media and bringing a second surface of the workpiece into contact with the testing media, and 
     a sealing mechanism for preventing contact of the testing media and the first surface of the workpiece. 
     In one or more embodiments, the first well portion includes: 
     a body including a recess for receiving the workpiece; and 
     an opening in the body through which the working electrode lead passes to make contact with the first surface of the workpiece. 
     In one or more embodiments, the sealing mechanism includes: 
     a mechanical seal for location between the second surface of the workpiece and the second well portion; and 
     co-operating engagement members to cause the workpiece and the second well portion to bear against each other. 
     In one or more embodiments, the cooperating engagement members pass through aligned openings formed respectively in the first and second well portions. 
     In other embodiments, the cooperating engagement members act to clamp or crimp surfaces of the first and second well portions together. 
     In one or more embodiments, the mechanical seals of the plurality of testing wells are unitary. 
     In one or more embodiments, one or both of the first well portions and the second well portions of the plurality of testing wells are unitary. 
     In one or more embodiments, the second well portion is formed from a chemically stable, electrically and ionically insulating and/or conductive material. 
     Another aspect of the invention provides use of the testing board to perform electrochemical testing, the test board including a plurality of testing wells, each well including a first well portion for holding a workpiece to be tested and bringing a first surface of the workpiece into contact with a separate working electrode lead for each testing well, a second well portion for holding a testing media and bringing a second surface of the workpiece into contact with the testing media, and a sealing mechanism for preventing contact of the testing media and the first surface of the workpiece, wherein 
     in an electrochemical testing system including the testing board, a media delivery system, testing apparatus, a motion control system and at least one sensing head for securing one or more electrochemical sensing elements at least one of which is adapted to form part of an electrochemical circuit with the testing media, workpiece and working electrode lead for each testing well, each testing well being electrically and physically isolated from other testing wells, 
     the media delivery system selectively delivers the testing media into the second well portion; 
     the testing apparatus measures electrical and/or chemical properties from the electrochemical circuit; and 
     the motion control system controls relative movement of the sensing head and the plurality of testing wells so that the one or more sensing elements are selectively brought into contact with the testing media in the testing well of a selected workpiece to be tested. 
     Another aspect of the invention includes a process for calibrating an electrochemical testing system as described hereabove, including the steps of: 
     placing a reference workpiece in one of more testing wells; 
     causing the media delivery system selectively delivering calibration testing media to the one of more testing wells holding reference workpieces; 
     causing the motion control system to control relative movement of the sensing head and the one of more testing wells holding reference workpieces so that the one or more sensing elements are selectively brought into contact with the calibration testing media; and 
     reading calibration values from the sensing elements. 
     The use of one or more of the wells to calibrate the sensing head ensures that the sensing heads are performing within specified calibration limits. The calibration well may comprise a blank sample or a reference sample which is preferably certified. The advantage of testing the experimental wells and calibration wells co-currently is that systematic errors related to environmental conditions can be quantified. 
     Another aspect of the invention provides a process for using an electrochemical testing system as described hereabove, including the steps of: 
     loading identical workpieces which can be loaded into a plurality of testing wells; and 
     running identical testing procedures on the plurality of testing wells. 
     The present invention is particularly beneficial in being able to rapidly screen multiple samples without the need for repeat testing. However, the high throughput capacity of the present invention does also allow for multiple testing of the sample experiments, when statistical rigor is required. For example, when measuring parameters which have a high random error, at least two or three experiments may be run. 
     Another aspect of the invention provides a process for using electrochemical testing system as described hereabove, including the steps of: 
     running identical testing procedures on the same testing well multiple times. 
     This type of testing includes cyclic testing in which the electrochemical properties of a system may be tested after each charge/discharge cycle or internals thereof. Cyclic testing are an important benchmark used by industry, with the scaling up of an particular electrochemical cell often not progressing until cyclic performance has been determined. The present invention enables a greater number of electrochemical cells to undergo cyclic testing and thereby provide a greater opportunity of optimising cell chemistry. 
     Definitions: 
     Electrochemical properties: Properties relating to the chemical reactions which take place at the interface of an electrode and involve electric charges moving between the electrodes and the electrolyte. Properties may include ionic conductivity, capacitance and the window of electrochemical stability. Electrochemical measurements may include potentiometry, amperometry, coulometry, voltammetry (including cyclic voltammetry), potentiometry and impedance spectroscopy. 
     Chemical properties: Properties relating to the chemistry of a substance which may include their electrochemical properties. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The following description refers to in more detail to the various features of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the electrochemical testing system is illustrated in a preferred embodiment. It is to be understood that the electrochemical testing system of the present invention is not limited to the preferred embodiment as illustrated in the drawings. 
       In the drawings: 
         FIG. 1  is a schematic diagram of an electrochemical testing system according to one embodiment of the present invention; 
         FIGS. 2( a ) and 2( b )  are isometric and plan views respectively of two layers of a testing board forming a plurality of testing wells forming part of the electrochemical testing system shown in  FIG. 1 ; 
         FIGS. 3( a ), 3( b ) and 3( c )  are isometric views of the layer of the testing board shown in  FIG. 2( b )  and depicts a sequence of operations during use of the electrochemical testing system shown in  FIG. 1  to test a workpiece held in the testing board shown in  FIG. 2 ; 
         FIGS. 4( a ) to ( c )  depict respectively a plan, side and bottom view of a portion of the testing board shown in  FIG. 2  after assembly is complete; 
         FIG. 5  is a schematic side view of a sensing head forming part of the electrochemical testing system shown in  FIG. 1 ; 
         FIG. 6  is a schematic plan view of the sensing head shown in  FIG. 5 ; 
         FIG. 7  is an illustrative electrical connectivity diagram of the sensing head shown in  FIGS. 5 and 6  when positioned so that sensing elements held by the sensing head are brought into contact with testing media in a testing well forming part of the testing board shown in  FIG. 2 ; 
         FIG. 8  is a schematic diagram of a computer system forming part of the electrochemical testing system shown in  FIGS. 1 ; and 
         FIGS. 9 and 10  are flow charts depicting a sequence of operations performed by the electrochemical testing system shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , there is shown generally an electrochemical testing system  10  for testing workpieces held in a plurality of testing wells the exemplary ones of which are referenced  12  to  16  in this figure. The number of testing well are only limited by practical consideration, but are preferably comprise at least 5 testing wells, preferably at least 10 testing wells, more preferably at least 50 testing wells and even more preferably at least 100 testing wells. The testing wells  12  to  16  are each capable of holding a workpiece to be tested and forming a contained volume into which a testing media or electrolyte, such as a suitable fluid or gel, is introduced and brought into contact with the workpiece. 
     The electrochemical testing system  10  includes a sensing head  18  for securing one or more sensing elements, such as one or more electrodes or ion-selective probes. One or more sensing elements may be adapted to form part of an electrochemical circuit, together with the testing media in each of the testing wells  12  to  16 , the workpiece itself and a working electrode lead that makes contact with the workpiece held within a relevant well. In such an arrangement, the workpiece effectively becomes the working electrode of the electrochemical testing system  10 . It will be appreciated that not every sensing element need form part of an electrochemical testing circuit. For example, one or more sensors/probes (e.g. pH, spectroscopic, hyperspectral, optical) may be secured to the sensing head  18  for in situ data collection of important and/or complimentary data useful to an experimenter. 
     A number of sensing heads each supporting one or more sensing elements may be prepared in advance. The various sensing heads may be interchangeable to facilitate the rapid testing of workpieces. 
     At least one sensing head may be adapted to secure one or more non-electrochemical sensing elements to perform non-electrochemical testing and measure one or more non-electrochemical properties such as compositional characteristics of the media and/or workpiece (e.g. electrode), such as moisture content, degradation by-products and migrated species. 
     For example, the non-electrochemical sensing/analysis elements may include a raman spectroscopic system/probe or a fibre-optic camera, ion selective electrodes, solid-state physical or chemical sensors, macroscopic imaging systems, microscopic imaging systems, NIR imaging, UV-Vis systems, FTIR systems, general measurement/analysis techniques and those considered state-of-the-art. The electrochemical testing system  10  also includes a media delivery system  20  for selectively delivering fluid, gel or other testing media into the testing wells  12  to  16 . The media delivery system  20  notably includes exemplary media delivery tubing  22  running between one or more media storage units (not shown) and one or more media delivery output nozzles which will be explained in relation to  FIG. 5 . One or more pump units  24  are provided as part of the media delivery system  20  to selectively cause delivery of the media along the tubing  22  and out of the nozzles. The media delivery system  20  is adapted to handle volumes of liquid in the range of 1 nL to 1 L or above. 
     In some embodiments, the media is in a solid form (e.g. solid electrolyte), such as a film or composite material (e.g. ion conducting polymers) The media delivery system is such embodiments preferably comprises a robotic “pick and place” mechanism which transfers pre-cut solid electrolytes into the wells. An alternative mechanism is deliver of the solid electrolyte as a film covering the wells and then cutting (mechanically or via laser) a proportion of the film above the well, such that the film portion is deposited into the well after cutting. It would be understood that other variations of the delivery of the media would be available to those skilled in the art. 
     A programmable controller  24  is configured to control operation of the media delivery system  20  including controlling operation of the pump units  24 . As the media delivery system  20  is controlled by the programmable controller  26 , it is possible to actively control the dosage and desired chemical delivery for each testing well  12  to  16 . 
     In various embodiments of the invention, the pump units  24  may be either analogue or digitally controlled and may include but are not limited to syringe pumps, diaphragm pumps, peristaltic pumps, mechanical pumps, impellor pumps, as well as conventional pumping, dosage and metering techniques or solutions. 
     Connections between the pump units  24  and the micro-fluidic tubing or other piping is preferably chemically resistant and leak proof. 
     Although not depicted in  FIG. 1 , solenoids may also be included in the fluid path  22  to arrest, or redirect media flow when used in conjunction with a manifold suitable for fluid or viscous liquids. Inline mixing chambers may also be included in the fluid path. The nozzles or other outputs from the tubing  22  connected to the pump units may either be terminated individually at the sensing head  18  as shown in  FIG. 1 , or combined together upstream in a fluid path to ensure adequate mixing of solutions, gels or other media. Moreover, whilst  FIG. 1  depicts the mounting of the nozzles at the sensing head  18 , it is also possible to provide a separate media delivery system operating independently of and physically apart from the sensing head  18 . 
     The electrochemical testing system  10  also includes a motion control system  28  for controlling relative movement of the sensing head  18  and the testing wells  12  to  16  so that one or more sensing elements mounted to the sensing head  18  are selectively brought into contact with testing media held within a selected one of the testing wells  12  to  16  in which a selected workpiece to be tested is held. The motion control system  28  may take a number of forms, but in one or more embodiments includes a servo or other drive mechanism  30  for driving one or both of the testing wells  12  to  16  and the sensing head  18  along three orthogonal axes. 
     In the embodiment depicted in  FIG. 1 , the servo mechanism  30  includes a servo motor  32  driving a spindle  34  which in turn connects to a ball screw  36 . Operation of the servo motor  32  causes rotation of the ball screw  36  about its longitudinal axis. A coupling device  38  interconnects the sensing head  18  and the ball screw  36  so that the rotational movement of the ball screw  36  is translated into linear movement of the coupling device  38 . It will be appreciated that the arrangement depicted in  FIG. 1  is replicated along X, Y and Z orthogonal axes in order to provide three dimensional movement of the sensing head  18 . 
     An encoder  40  is coupled to the servo motor  32  and provides a series of pulses to the servo control circuit  42  to enable a determination of the angular position of the spindle  34 . In addition, an optical scale  44  converts linear movement of the coupling device  38  in the X, Y or Z axis into pulses to enable the servo control circuit  42  to determine the linear position of the coupling device  38  along each of the three orthogonal axes. The servo motor  32  is controlled by signals from a servo amplifier  46  which is in turn controlled by the servo control circuit. 
     It will be appreciated that the servo mechanism  38  is merely one example of an arrangement for selective positioning of the sensing head with respect to the testing wells. Other embodiments of the invention may include a combination of components conventionally used in servo mechanisms, such as transducers, stepper motors, actuators and servos. It will also be appreciated that in other embodiments of the invention relative positioning of the sensing head  18  and the testing wells  12  to  16  may provide along three or more axis of movement. 
     In use, the servo control circuit  42 , acting under control of the programmable controller  26 , typically causes the sensing head  18  to be positioned over a relevant testing well  12  to  16 . The sensing head  18  is then lowered into the relevant testing well, and reagents, fluid or other testing media is dispensed into the relevant testing well as required. A testing sequence then begins, and after conclusion the sensor head is retracted from the well. The sensor head  18  may then be moved by the servo control circuit  42  to a cleaning station  48  where the sensor head  18  is decontaminated with de-ionised water or any appropriate fluid/solvent/chemical/gas, etc. The electrochemical testing system  10  is then ready to begin the next step. 
     A variety of reagents, fluid or other testing media can be dispensed into the testing wells, such as electrolytes, ionic liquids, solvents, stabilisation agents and corrosion inhibitors. Examples of the testing media or electrolyte that may be used are listed in paragraphs 18 to 75 of EP1365463. Examples of electrode materials which may form part of the electrochemical testing system are listed in paragraphs 70 to 94. 
     In some embodiments, individual electrolyte components can be directly deposited into the wells. This is advantageous in regard to reducing contamination, including cross contamination, degradation (e.g. oxidation) and minimising wastage. The open cell structure of the testing wells also facilitates the dosing of highly viscous materials (e.g. ionic liquids) and enabled dosing pipes to be heated to facilitate flow. 
     Moreover, while it is possible to pre-dispense liquids before testing, the system  10  facilitates on-demand dosing, thus mitigating issues of evaporation during long testing cycles which would typically range from 3 to 7 days. 
     As can be best seen in  FIG. 2 , each of the testing wells  12  to  16  includes a first well portion  60  for holding a workpiece  62  to be tested. The first well portion  60  also acts to bring a first surface  64  of the workpiece into contact with an end of working electrode lead  66 . In that regard, the first well portion  60  includes a body  68  having formed therein a recess  70  for receiving the workpiece  62 . An aperture  72  is formed through the body  68  providing communication between the recess  70  at the interior of the testing well and an exterior surface  74  of the testing well. The working electrode lead passes through the aperture  72  to make contact with the surface  64  of the workpiece  62  thereby providing an externally accessible electrical connection to the surface  64  of the workpiece  62 . In other embodiments, a recess, trough or other opening may be used in place of the aperture  72 . 
     Each testing well also includes a second well portion  78  for holding a fluid, gel or other testing media, and for bringing a second surface of the workpiece  62  in to contact with the testing media. A sealing mechanism  82  is also provided for preventing contact of the testing medium and the first surface  64  of the workpiece  62 . The second well portion  78  is preferably formed from a chemically stable, electrically and ionically insulating and/or non-conductive material 
     In the embodiment depicted in  FIG. 2 , the sealing mechanism  82  includes a mechanical seal, such as a gasket  84 , for location between the second surface  80  of the workpiece  62 , as well as cooperating engagement members to cause the workpiece  62  and the second well portion  78  to be against each other. The cooperating engagement members, which may include a plurality of nuts and bolts, pass through aligned openings formed respectively in the first and second well portions. In  FIG. 2 , an exemplary bolt  86  and corresponding nut  88  are depicted. The bolt  86  passes through an aperture  90  formed respectively in the first well portion  60  and second well portion  78 . In other embodiments, the cooperating engagement members may be crimps or clamps that act to crimp or clamp surfaces of the well portions  60  and  78  together. 
     It will be appreciated that a variety of means may be provided to prevent contact of the testing media and the first surface  64  of the workpiece  62 . Such sealing arrangements may include application of liquid sealants and adhesives, although these alternative embodiments would make disassembly of the testing wells into the component parts more difficult. 
     The various testing wells forming part of the electrochemical testing system  10  may form part of a testing board or other larger structure. In the embodiment depicted in  FIG. 2 , the first well portions of the various testing wells are unitary form the lower half  100  of a testing board  102 . The second well portions of the testing wells are also unitary and in this embodiment form a top half  104  of the testing board  102 . Although in this embodiment the gaskets used in the sealing mechanisms of each testing well are individually formed and applied, in other embodiments of the invention the gaskets may also be unitary and that unitary structure applied to the bottom half  100  of the testing board  102  prior to placement of the top half  104  over the gaskets. 
     A more detailed view of a first well portion  120  forming part of a unitary structure can be seen in  FIG. 3 . This figure also depicts the recess  122  formed in the body  120 , the aperture  124  formed through the body  120  and into the recess  122 , the working electrode lead  126  passing through the aperture  124  for making contact with a workpiece  128  that is subsequently located in the recess  122 . Finally, this figure depicts an exemplary circular gasket  130  located on the upper surface of the workpiece  128  and against which a second or upper well portion is subsequently located. 
       FIG. 4  shows in more detail a small exemplary testing board sub-unit  140  and notably depicts the manner in which a plurality of bolts  144  and nuts  146  are used as part of a sealing mechanism for preventing contact of the testing media with an upper surface of the workpiece located in the testing wells. It should be noted that alternative methods for maintaining the unitary configuration of testing board  140  in  FIG. 4  may also include other mechanical or chemical methods such as crimps or adhesive media, or methods known to those skilled-in-the-art. In addition, this figure shows the manner in which working electrode leads from each of the testing wells run along grooves  148  to  152  in order to bring electrical connections to those working electrode leads to a convenient external location so that the working electrode leads can form part of an electrode chemical circuit for testing. 
     The number of testing wells in a testing board is preferably as high as can be physically accommodated by the mechanical range of the motion control system  28  and the physical space limitation of the testing area. In one exemplary system,  81  testing wells are used, with individual testing boards assembled as  9  well sub-units of the sort depicted in  FIG. 4 . Liquid volume of the testing cell should be in the 10&#39;s of mL range, while smaller volumes are possible, oxygen diffusion rates (if testing in ambient environments) become very high, and the equilibrium of the electrochemical system shifts, which can result in non-representative data. In some instances, low testing volumes may be desirable, as a sort of accelerated testing. 
     It will be appreciated that the testing board depicted in  FIG. 2  serves to hold the workpieces in place, provide a physical scaffold onto which an electrical connection to the working electrode lead can be established, and seals the workpiece against the upper portion of the testing board, creating a testing space into which liquids, solids and gels can be brought into direct contact with the workpiece. 
     The working electrode can be made of any electro active material, typical examples of which are pure metals, alloys, carbon containing materials, and intercalation electrode such as metal oxides. In order to test non-idealised samples the first and second well portions and sealing mechanism can be modified to accept a variety of different geometries, extending testing capabilities past planar samples. Unlike other electrochemical testing systems which are limited to research and development, the electrochemical testing system described here is capable of testing manufactured samples/object, which is particularly important as idealised research and development samples are often not truly representative mass produced materials, which is what will ultimately be the contextualised focus of an industrially relevant electrochemical testing system. 
     The upper portion of the testing board  102  is preferably made from any chemically resistant material which also provides electrical insulation. 
     In other embodiments of the invention, the component testing board  102  may be fabricated as a single piece. It is also possible to fabricate the testing board to accommodate a larger or smaller number of wells as depicted in  FIG. 2 . Therefore, it is possible to fabricate smaller sub units of the testing board which may be combined to make one larger testing board. 
     It is to be understood that the diameter of the wells must be sufficient to suit experimental requirements, however, the wells should ideally be of sufficient volume to prevent displacement of the testing media and sensors or probes from the sensing head  18  are inserted into the well. 
     As seen in  FIGS. 5 and 6 , the sensing head  18  used to secure one or more sensing elements each adapted to form part of an electrochemical circuit with the testing media workpiece/working-electrode lead. These sensing elements include a counter electrode  160 , a reference electrode  162  and a pH sensor  164 . In other embodiments of the invention, other ion-selective probes may be provided as an alternative to or in addition to the pH sensor  164 . In further embodiments, spectroscopic measurement techniques and a variety of other probes and sensors could be used in addition to or as an alternative to the arrangement shown in  FIGS. 5 and 6 . The sensing head  18  is used to secure the various sensing elements  160  to  164  to the motion control system  28 . In that regard, the sensing head  18  is connected to the end of a robotic manipulator  166  by means of a bayonet fitting  168  permitting rapid removal of the sensing head  18 . The sensing elements  160  to  164  are connected to the bayonet fitting  168  by an assembly  170 . 
     It will be appreciated that in other embodiments, two or more of the elements depicted in  FIGS. 5 and 6  may be formed as a single part. 
     The counter electrode  160  can be made from carbaceous materials or noble metals Pt, Au, etc. A fritted referenced electrode is typically employed (e.g. including Ag/AgCl, Calomel, specialist fritted electrodes where the solution is non-aqueous. Quasi-referenced electrodes, such as Ag, Pt, etc, may also be used. 
     Sensor head materials which incorporate the electrodes and other sensors can be made from materials such as metals, alloys, plastic/polymer(s), ceramics or the like. 
     The size and geometry of the electrodes should ideally be aligned so that they can be inserted into the testing well without completely displacing the solution or damaging the electrodes themselves. 
     To complete the electrochemical circuit which is necessary to perform electrochemical measurements of the workpiece, each testing well is electrically addressable and electrically and physically isolated from all other testing wells. This prevents the marring of electrochemical measurements by parasitic or concurrent chemicals/mechanical/electrochemical processes that would occur if testing occurred on a single workpiece only. 
     Utilising individual workpieces rather than a larger approximate sample means that individual manufactured components can also be tested. Some examples of manufactured samples could include: screws, nuts, bolts, washers, metal coupons, enclosures, wire, coils, cylinders, vessels, panelling, bearings, capsules, containers, shielding, etc. 
     An example of testing apparatus for measuring electrochemical and/or chemical properties from the electrochemical circuit is shown in  FIG. 7 . In this exemplary implementation, the electrical testing apparatus  180  includes at least one electrochemical measurement instrument, in this case a potentiostat  182 , having inputs connected to the working electrode and one or more of the sensing elements (in this case both the reference electrode and counter electrode). The potentiostat also includes an output connected to measurement recording apparatus, which in this case is embodied by the programmable controller  26  in conjunction with the database  50  shown in  FIG. 1 . 
     Whilst the potentiostat  182  measures the voltage difference between a working electrode and a reference electrode in an electrochemical cell, it is to be understood that a variety of probes, sensors and instruments can be used to measure a range of electrochemical properties. 
     To establish an electrical/electronic circuit between one or more instruments, such as the potentiostat  182 , a galvanostat, other scientific/analytical measurement instrument(s) or data logging device(s), and the testing board  102 , many connections can conveniently be multiplexed into a single connection by circuitry, such as a multiplexer  184 , that connects the working electrode of a selected testing well to the electrochemical testing circuit. Conventional multiplexers, relay arrays (for example, reed, mechanical, micro, etc.) or other single switching/shunting technologies can be employed. 
     In other embodiments, a bus topology network may be used in place of the multiplexer  184  to simplify circuit design. In such a network, each instrument would be connected to a single cable or backbone and individually addressable on that backbone by the programmable controller  26 . 
     Addressing of the individual testing wells is carried out by the programmable controller  26 . The sensors, electrodes and other devices residing within the testing head  18  (as a stand-alone unit, or as part of an interchangeable arrangement) can be directly wired into testing/analytic instrumentation. 
     Alternatively, electrical connection to the reference and counter electrodes, pH probe or other attached sensors/probes can occur via multiple single-core or several multi-core cables/wiring to one or more patch panels located near the motion control system  28 . Such panels allow for the rapid connection of instrumentation and power sources to sensors, electrodes, probes, motors, light sources or any utilised attachment. 
     It is also possible to use wireless or optical transmission in lieu of conductive wiring to achieve the same functionality/connectivity. It is also possible to use a bus connection topology to eliminate the need for electrically individually addressable testing wells. This eliminates the need for a multiplexing system, thus simplifying the design shown in  FIGS. 1 and 7 . 
     Operation of the servo mechanism  30 , electrical testing apparatus  180 , media delivery system  20  and other elements of the electrochemical testing system  10  is achieved by the programmable controller  26 . In that regard, data from connected instruments, pumps and ancillary devices is captured by the programmable controller  26  and stored in the data base  50 . A graphical user interface  52  is provided to enable an operator to set up a testing routine, control movement of the motion control system, analyse data and provide real time output of events, including error messages and take like actions. Data is stored in the database  50  on a per-experiment basis, with all variables such as inputs, outputs and time stamps recorded in the database  50 . 
     The graphic user interface  52  enables individual samples to be electronically registered by an operator with a unique sample ID and material ID. In that regard, barcodes, RFID tags or other machine readable identifiers can be applied to individual samples, and read by a manual operable tag/code reader or the like. Calibration or re-zeroing and positioning of the motion control system  28  can also be performed by a user. The graphic user interface  52  can also enable an operator to specify parameters of media delivery system components such as flow rate, allow manual definition of what volume of which chemical is to be dispensed in any given testing well, enable users a selection of scan settings, testing protocols etc, as well as a variety of other user operable functionality that may be programmed in to the programmable controller  26 . 
     The programmable controller  26  and graphic user interface  52 , as well as various other elements of the electrochemical testing system  10 , may be provided by one or more computer systems capable of carrying out the above described functionality. An exemplary computer system  200  is depicted in  FIG. 8 . The computer system  200  includes one or more processors, such as the processor  202 . The computer system may include a display interface  204  that forwards graphics, text and other data from a communication infrastructure  206  or display to a display unit  208 . The computer system  200  may also include a main memory  210 , preferably random access memory, and may also include a secondary memory  212 . 
     The secondary memory  212  may include, for example, a hard disc drive  214 , or optical disk drive or the like. A removable storage drive  216  reads from and/or writes to the removable storage unit  218  in a well-known manner. The removable storage unit  218  represents an optical disc, CD, DVD or like data storage device. 
     As will be appreciated, the removable storage unit  182  includes a computer usable storage medium including a non-volatile memory having stored therein computer software in the form of a series of instructions to cause the processor  202  to carry our desired functionality. In alternative embodiments, the secondary memory  212  may include other similar means for allowing computer programs or instructions to be loaded into the computer system  200 . Such means may include, for example, a removable storage unit  220  and corresponding interface  222 . 
     The computer system  200  may also include a communications interface  224 . The communications interface  224  allows software and data to be transferred between the computer system  200  and external devices. Examples of the communication interface may include a modem, network interface, communications port. Software and data transfer via the communications interface  224  are in the form of signals which may be electro-magnetic, electronic, optical or other signals capable of being received by the communications interface  224 . The signals are provided to the communication interface  224  via a communications path  226  such as a wire, cable, fibre optics, phone line, cellular phone link, radio frequency or other communication channel, including the communications bus  54  depicted in  FIG. 1 . 
     In the context of the present invention it is to be understood that the “computer system” is intended to encompass arrangements that are less complex than the computer system  200 , including notably a microcontroller, microprocessor or the like. 
       FIGS. 9 and 10  depict two exemplary testing procedures performed by the electrochemical testing system  10  under control of the programmable controller  26 . In the testing procedure  206  depicted in  FIG. 9 , the graphic user interface  52  is activated at step  262 , from where an operator selects to run a pH calibration process at step  264 . Acting under the control of the programmable controller  26 , the motion control system  28  acts to then move the sensing head  18  over a relevant testing well at step  266 . At step  268 , the programmable controller  26  causes the media delivery system  20  to dispense an appropriate amount of testing liquid/solution/gel and applicable reagents into the relevant well. 
     After a pause for equilibration at step  270 , a generalised electrochemical measurement is performed, such as determining the open circuit potential of the electrochemical circuit being tested at step  272  or in a polarisation scan at step  274 . 
     Once these measurements have been performed, the testing head  18  is withdrawn from the testing well at step  276 , and moved to the cleaning station  48 , where at step  278 , the sensing head  18  is cleaned with suitable cleaning fluid. 
     At step  280 , the programmable controller  26  determines whether additional tests are to be run. If it is determined at step  282  that all testing has completed, then operation of the electrochemical testing system  10  ceases at step  284 . 
     An example of the pH calibration testing procedure  286  is depicted in  FIG. 10 . In general terms, this procedure, a reference workpiece is placed in one or more testing wells. The media delivery system then selectively delivers calibration testing media to the one of more testing wells holding reference workpieces, and the motion control system is caused to control relative movement of the sensing head and the one of more testing wells holding reference workpieces so that the one or more sensing elements are selectively brought into contact with the calibration testing media. Calibration values are then read from the sensing elements. 
     Specifically, the procedure depicted in  FIG. 10  relates to a multi-point pH calibration performed by the electrochemical testing system  10 . In this testing procedure, the testing head  18  is moved to a pH buffer solution stored in one of the testing wells or other suitable location at step  288 . At step  290 , the sensing head is lowered into the solution and, at step  292 , after a pause for equilibration, the pH is recorded. 
     At step  294 , the sensing head  18  is withdrawn and moved to the cleaning station  48  where the sensing head is cleaned at step  296 . At step  298 , a count is made of the number of pH calibration solutions that have been calibrated and, if it is determined at step  300  that less than a desired number of calibrations have occurred, then steps  288  to  298  are repeated. Once the desired number of calibrations have taken place, then at step  302 , the stored data in the database  30  is interrogated and the programmable controller  26  acts to calculate a calibration offset which is to be applied to future readings. In other words, the pH calibration is run for pH 4, 7 and 10 (once for each calibration solution), after which generalised testing begins from step  266  onwards in  FIG. 9 . 
     The electrochemical testing system  10  can be designed for rapid screening in which each testing well is used to perform a discrete testing procedure without repeats. 
     However, the electrochemical testing system  10  can also be configured to perform testing procedures, such as those depicted in  FIGS. 9 and 10 , on multiple samples in parallel. That is, identical workpieces can be loaded into a plurality of testing wells and identical testing procedures run. A repeat function can easily be programmed into the computer system  200  which will perform the same test in two or more testing wells, which improves the general scientific rigour of the system and makes it compatible with standard testing procedures. For example, three separate samples can be measured and the results averaged. 
     The electrochemical testing system  10  can also be configured to perform cyclic testing, where each individual test well is tested multiple times. This is extremely useful for performing aging studies of materials and perturbing samples to environmental/system extremes to monitor the response of the sample. 
     While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternatives, modifications or variations in light of the foregoing description are possible. The present invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the invention as disclosed.