Sensor interposer employing castellated through-vias

Abstract

To provide a sensor interposer employing castellated through-vias formed in a PCB.SOLUTION: A sensor interposer includes: a planar substrate defining a plurality of castellated through-vias; a first electrical contact formed on the planar substrate and electrically coupled to a first castellated through-via; a second electrical contact formed on the planar substrate and electrically coupled to a second castellated through-via; the second castellated through-via electrically isolated from the first castellated through-via; and a guard trace having a first portion and a second portion, the first portion being formed on the first surface of the planar substrate and electrically coupling a third castellated through-via to a fourth castellated through-via, the second portion being formed on the second surface of the planar substrate and electrically coupling the third castellated through-via to the fourth castellated through-via, the guard trace providing electrical isolation between the first and second electrical contacts.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates generally to wearable biosensors, and more specifically to sensor interposers employing castellated through-vias. [Background technology]

[0002] Existing wearable biosensors, such as continuous glucose monitors, integrate the analyte sensor into the wearable device as a fully modular assembly so that the device can be worn on the body and the sensor wires placed on the body simultaneously in one motion. As a result, the sensor wires need to be electrically connected and mechanically assembled to the device prior to placement during device manufacture or assembly. Summary of the Invention [Means for solving the problem]

[0003] The present application relates to a planar substrate defining a plurality of castellated through vias; a first electrical contact formed on the planar substrate and electrically coupled to the first castellated through via; a second electrical contact formed on the planar substrate and electrically coupled to the second castellation through via, the second castellation through via being electrically insulated from the first castellation through via; A sensor interposer is provided that includes: a guard trace formed on the planar substrate, the guard trace being electrically coupled between third and fourth through vias formed on the planar substrate, the guard trace insulating the first and second electrical contacts.

[0004] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more specific examples and, together with the description of the examples, serve to explain the principles and implementations of the particular examples. [Brief description of the drawings]

[0005] [Figure 1] 1 illustrates an exemplary sensor interposer employing castellated through-vias formed in a printed circuit board ("PCB"). [Diagram 2] 1 illustrates an exemplary sensor interposer employing castellated through-vias formed in a printed circuit board ("PCB"). [Figure 3A] 1 illustrates an exemplary sensor interposer employing castellated through-vias formed in a PCB. [Figure 3B] 1 illustrates an exemplary sensor interposer employing castellated through-vias formed in a PCB. [Figure 4] 1 illustrates an exemplary sensor interposer employing castellated through-vias formed in a PCB. [Figure 5A] 1 illustrates an exemplary wearable biosensor device that includes a sensor interposer that employs castellated through-vias formed in a PCB. [Figure 5B] 1 illustrates an exemplary wearable biosensor device that includes a sensor interposer that employs castellated through-vias formed in a PCB. [Figure 5C] 1 illustrates an exemplary wearable biosensor device that includes a sensor interposer that employs castellated through-vias formed in a PCB. [Figure 6] 1 illustrates an exemplary method for manufacturing a sensor interposer employing castellated through-vias formed in a PCB. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Examples are described herein in the context of a sensor interposer employing castellated through-vias. Those skilled in the art will appreciate that the following description is illustrative only and is not intended to be limiting in any way. Reference will now be made in detail to example implementations that are illustrated in the accompanying drawings. The same reference indices are used throughout the drawings and the following description to refer to the same or similar items.

[0007] For clarity, not all of the routine features of the examples described herein are shown and described. Of course, it will be understood that the development of any such actual implementation will require many implementation-specific decisions to be made in order to achieve the particular goals of the developer, such as adhering to application-related and business-related constraints, and that these specific goals will vary from implementation to implementation and developer to developer.

[0008] Some wearable biosensors employ one or more invasive sensor wires that are inserted into the wearer's skin. The sensor wire typically includes at least two separate electrodes and has a quantity of chemical, such as glucose oxidase ("GOX"), deposited on the end of the sensor wire that is inserted into the wearer's skin. The chemical then reacts with an analyte present in the wearer's interstitial fluid, which generates a current that can be sensed by the biosensor's electronics. However, the amount of current generated can be very small, for example, on the order of tens of nanoamps, and these chemicals can be heat sensitive, making the design and manufacture of biosensors difficult. For example, biosensors need to be designed to prevent leakage currents that can interfere with the current generated by the reaction between the chemical and the analyte. In addition, manufacturing processes that include high heat steps, such as soldering, can damage the chemicals as they are heated.

[0009] To address these and other challenges, an exemplary wearable biosensor may employ a main PCB having electronics such as a microcontroller or wireless transceiver, a battery, etc. In addition, the exemplary device employs a secondary PCB assembly (commonly referred to as an "interposer") to mechanically secure the sensor wires while also providing electrical contacts to the different electrodes present on the sensor wires. The interposer may then be electrically and physically coupled to the main PCB, such as by soldering. To help reduce the amount of heat transferred to the interposer during soldering, the exemplary interposer employs castellated through-vias to provide electrical connections between the main PCB and the interposer, and to provide soldering locations that are relatively thermally isolated from the sensor wires themselves.

[0010] In this example, the interposer has through vias formed around the footprint of the interposer. The interposer is then cut out of the larger PCB board so that the through vias are cut out, exposing the inner portions of the through vias. The exposed inner portions of the through vias can be aligned with corresponding electrical contacts on the main PCB and soldered together. Because the solder points are located inside the through vias and essentially on the opposite side of the PCB from the electronics on the interposer PCB, heat transfer from the soldering process to the interposer electronics, including the sensor wire, is significantly reduced. Additionally, the use of through vias allows one or more guard rings to be formed to surround the interposer and provide electrical isolation between different electrical contacts formed on the interposer, such as electrical contacts to different electrodes formed in the sensor wire.

[0011] This diagrammatic example is provided to introduce the reader to the general subject matter described herein, and the disclosure is not limited to this example. The following sections describe various additional non-limiting examples, as well as example systems and methods, for sensor interposers employing castellated through-vias formed in a PCB.

[0012] Referring now to FIG. 1, FIG. 1 illustrates an exemplary sensor interposer 100 employing castellated through-vias. In this example, the sensor interposer includes a planar substrate, i.e., in this example, a PCB. Any suitable PCB material may be employed, including FR4, polyimide, and the like. Two electrical contacts 112, 114 are formed on the top surface of the PCB. Each electrical contact 112, 114 is sized and shaped to allow a sensor wire 120 to be electrically and physically coupled thereto, for example, by clamps, adhesive, or any other suitable physical coupling technique. In this example, the sensor wire is formed of two electrodes formed coaxially, and prior to use, the sensor chemical (e.g., glucose oxidase) may be deposited at the distal end of the sensor wire, i.e., the end of the sensor wire, which is inserted into the wearer's skin. The proximal end of the sensor wire exposes each electrode to allow each electrode to be electrically and physically coupled to a different one of the electrical contacts 112, 114. In this example, the working electrode ("WE") is coupled to electrical contact 114, while the counter electrode ("CE") is coupled to electrical contact 112. Additionally, each electrical contact 112, 114 is electrically coupled to a castellated through via formed at the periphery of the PCB material. When the interposer 100 is physically and electrically coupled to the main PCB, the castellated through via 118 provides an electrical connection between the electrical contacts 112, 114 and the sensor electronics located on the main PCB. In this example, the interposer 100 has two electrical contacts 112, 114, however, some examples may employ multiple sensor wires and may require additional electrical contacts based on the type(s) of sensor wire(s) employed. Additionally, in some examples, the sensor wire may include more than two electrodes. For example, multiple electrodes may be formed overlapping in successive planar layers. Each layer may be coupled to a different electrical contact formed on the planar substrate. Additionally, the different electrodes may have different sensor chemistries applied to them.Suitable sensor chemistries include those for sensing acetylcholine, amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growth hormone, hormones, ketones, lactate, peroxide, prostate specific antigen, prothrombin, RNA, thyroid stimulating hormone, or troponin.

[0013] In this example, the planar substrate 110 (or interposer substrate) also defines an opening 124 between the two electrical contacts. The opening provides physical separation between the two electrical contacts 112, 114, thereby providing some electrical insulation therebetween. In addition, the opening allows for the formation of guard traces 116a-b that do not cross or contact the sensor wire 120. In some examples, the opening may be formed to have a shape that corresponds to one or more features formed on the main PCB to allow for alignment. However, it should be understood that such openings are not necessary in all examples and may be omitted based on design considerations.

[0014] In addition to the electrical contacts 112, 114, two guard traces 116a-b are formed on the interposer PCB. Each guard trace 116a-b surrounds a portion of the interposer PCB to provide electrical isolation between the two electrical contacts 112, 114. In this example, each guard ring includes a portion formed on the top surface of the interposer PCB 110 that electrically couples two corresponding castellation through vias. Each guard ring 116a-b also includes a portion formed on the bottom surface of the interposer PCB 110 that is also coupled to the same corresponding castellation through vias, providing a closed loop of material that surrounds a portion of the interposer PCB. In combination with the openings, the two guard rings 116a-b electrically isolate the two electrical contacts 112, 114 from each other. In some examples, one or both of the guard rings 116a-b may be coupled to a ground plane to help dissipate leakage currents.

[0015] In this example, the interposer 100 also includes a sensor wire 120 that is coupled to two electrical contacts 112, 114. The sensor wire 120 in this example has two coaxially arranged wire materials, one of which acts as a working electrode and the other of which acts as a reference or counter electrode. To allow for the two different coaxial portions of the sensor wire to be coupled to different electrical contacts, the inner wire material extends beyond the end of the outer wire material, but is partially covered with polyurethane insulation 122. In this example, the inner wire material is physically and electrically coupled to one electrical contact 114, and the outer wire material is physically and electrically coupled to the other electrical contact 112.

[0016] In this example, the sensor wire materials are (1) an inner wire material, platinum or platinum coated wire, and (2) an outer wire material, silver / silver chloride (Ag / AgCl) material. One end of the sensor wire 120 and a portion of the Ag / AgCl material is inserted into the patient's skin, and the other end of the sensor wire 120 is attached to an electrical contact. The Ag / AgCl material is bonded to a first electrical contact 112, and the platinum material is bonded to a second electrical contact 114.

[0017] Referring now to FIG. 2, FIG. 2 illustrates another exemplary sensor interposer 200 employing castellation through vias. In this example, the interposer 200 is formed from a planar substrate, which is a PCB 210. Similar to the example illustrated in FIG. 1, the interposer 200 has two electrical contacts 230a-b formed thereon. A sensor wire 250 is physically and electrically coupled to the electrical contacts 230a-b. In particular, the sensor wire has two coaxial electrodes 252a-b, which are physically and electrically coupled to respective electrical contacts 230a-b. Each electrical contact 230a-b is electrically coupled to a corresponding castellation through via 220b, 220c by an electrical trace formed on the PCB 210. The castellation through vias may later be physically and electrically coupled to electrical contacts on another PCB to allow electrical signals from the sensor wire 250 to be communicated to another PCB.

[0018] The interposer 200 also includes a guard trace 240 formed on the PCB 210. The guard trace 240 traverses the PCB 210 between the two castellation through vias 220a, 220d and between the two electrical contacts 230a-b, thereby electrically isolating them from one another. In this example, the guard trace 240 is formed on both the top surface (shown in FIG. 2) of the PCB and on the bottom surface opposite the top surface, where additional electrical traces are formed between the castellation through vias 220a, 220d. However, in some examples, the guard trace 240 may be formed only on the same surface as the electrical contacts 230a-b. In this example, unlike the example shown in FIG. 1, the PCB does not define a central opening. Thus, the guard trace 240 must pass under the sensor wire 250 without contacting the sensor wire 250, which may interfere with the electrical signal provided by the sensor wire 250 to the electrical contacts 230a-b.

[0019] 3A-3B, FIG. 3A illustrates an exemplary sensor interposer 300 employing castellation through vias formed in a PCB. In this example, the interposer 300 has a PCB 310 planar substrate that defines a central opening 322. In addition, the PCB 310 has four castellation through vias formed around its periphery, while two castellation through vias are formed around the periphery of the central opening 322.

[0020] Two electrical contacts 312, 314 are formed on the top surface of the PCB and are each electrically coupled to a corresponding castellated through via formed around the central opening 322. The electrical contacts 312, 314 are positioned to physically and electrically couple to the sensor wire 220.

[0021] In addition to the electrical contacts 312, 314, two "wrap-around" guard traces 316a-b are formed on the PCB 310. Each guard trace 316a-b surrounds a portion of the PCB 310 to provide electrical isolation between the two electrical contacts 312, 314. In this example, each guard trace 316a-b includes a portion formed on the top surface of the PCB 310 that electrically couples two corresponding castellation through vias. Each guard trace 316a-b also includes a portion formed on the bottom surface of the PCB 310 that is also coupled to the same corresponding castellation through via, providing a closed loop of material that surrounds a portion of the PCB 310. In combination with the openings, the two guard traces 316a-b electrically isolate the two electrical contacts 312, 314 from each other. In some examples, one or both of the guard traces 316a-b may be coupled to a ground plane to help dissipate leakage currents.

[0022] 3B shows the underside of PCB 310. The view shown in FIG. 3B also illustrates wrap-around guard traces 316a-b, which are electrically coupled by guard trace 316c, which couples two castellated through vias formed around the aperture. In some examples, guard trace 316c is not included, so that the two wrap-around guard traces 316a-b are electrically isolated from each other on PCB 310, but in some examples, they may be coupled to a common ground plane, such as a common ground plane formed on the main PCB of the biosensor.

[0023] Referring now to Figure 4, Figure 4 illustrates an example sensor interposer 400 employing castellated through-vias formed in a PCB. Such an example sensor interposer 400 may be integrated into a wearable biosensor, such as a continuous glucose monitor ("CGM"). The example CGM may include a main PCB that includes various electronic components, including a processor, discrete electronic components, and a wireless transceiver. A battery may be attached to and electrically coupled to the main PCB of the CGM to provide power to the electronic components of the CGM.

[0024] The exemplary sensor interposer 400 can be physically and electrically coupled to a main PCB, allowing signals from sensor wires of a CGM that are physically and electrically coupled to the sensor interposer 400 to be provided to electronic components on the main PCB, such as a processor.

[0025] The sensor interposer 400 in this example includes two electrical contacts 412, 414 formed on one side of the interposer 400 that are physically separated by an opening 422 defined around the periphery of the interposer 400. Each electrical contact 412, 414 is electrically coupled to a castellated through via. In addition, a guard trace 416 is formed on the same surface of the PCB 410 as the two electrical contacts 412, 414 to provide electrical isolation between the two electrical contacts 412, 414.

[0026] In addition to the electrical contacts and guard traces 416, the interposer 400 also includes additional electrical features. In this example, electrical tracers, designated as antennas 430, are formed on the PCB 410 and electrically coupled to castellated through-vias, allowing electrical and physical coupling of the CGM to the main PCB. In some examples, further electrical features may be provided on the PCB, including additional electrical contacts for physically and electrically coupling one or more additional sensor wires.

[0027] In some examples, the interposer 400 may be formed separately from the main PCB and the sensor wires may be physically and electrically coupled to the interposer 400 before the interposer 400 is physically and electrically coupled to the main PCB of the CGM, however, other orders may be employed as well, as described with respect to FIG. 6.

[0028] 5A-5C, FIG. 5A illustrates an exemplary wearable biosensor device 500 including a sensor interposer 520 employing through-castellation vias. In this example, the wearable biosensor device 500 includes a main PCB 510 on which the sensor interposer 520 and a sensor controller 540 are located. This exemplary device 500 includes the exemplary sensor interposer shown in FIG. 3, however, any suitable sensor interposer employing through-castellation vias may be employed.

[0029] In this example, the primary PCB 510 also defines surface features 512, such as pins, that engage with openings defined in the sensor interposer 520. FIG. 5B illustrates the primary PCB 510, which has surface features 512 defined thereon. The surface features 512 provide alignment features to enable alignment of the sensor interposer 520 with the primary PCB 510 and one or more electrical contacts formed on the primary PCB 510. FIG. 5C illustrates a top-down view of the primary PCB 510, which has surface features 512 formed and positioned to engage with the sensor interposer 520. Additionally, the primary PCB 510 has four electrical contacts 514a-d formed to engage with the castellated through vias 522a-d of the sensor interposer.

[0030]

[0033] Referring now to Figure 6, Figure 6 illustrates an example method 600 for manufacturing a sensor interposer employing castellated through-vias formed in a PCB. The example method 600 is described with respect to the example sensor interposer 100 shown in Figure 1, however, the example method according to this disclosure may be employed to manufacture any suitable example sensor interposer according to this disclosure.

[0031] In block 610, a suitable planar substrate 110 is provided. In this example, the planar substrate 110 is a PCB formed of a suitable material, such as FR4 or polyimide. The planar substrate 110 in this example has a size larger than the designed sensor interposer 100. Thus, in a later step, the planar substrate 110 can be cut to the size designed for the sensor interposer 100.

[0032] At block 620, one or more through vias 118 are formed in the planar substrate 110, such as at locations corresponding to the designed perimeter of the sensor interposer 100. Such through vias 118 may be formed to have a substantially circular (or other) cross-section, with a portion of the perimeter of the through via extending outside the designed perimeter of the sensor interposer 100. In some examples, one or more through vias 118 may also be formed in an interior portion of the sensor interposer 100. Such through vias 118 may be formed around a designed perimeter of an opening defined in the sensor interposer 100. For example, referring again to FIG. 1, two through vias were formed in the PCB 110 and cut to form castellation through vias when the central opening of the PCB 110 was formed. Any suitable number of through vias may be formed according to different examples. In this example, four through vias are formed around the designed perimeter of the sensor interposer, while two additional through vias are formed around the designed perimeter of the central opening of the sensor interposer 100.

[0033] At block 630, the planar substrate 110 is cut along the designed perimeter of the sensor interposer 100, including cutting through vias to form castellation through vias 118. In this example, the planar substrate 110 is further cut to form a central opening 124 and castellation through vias around the central opening 124.

[0034] At block 640, two electrical contacts 112, 114 are formed on the PCB 110 within the designed perimeter of the sensor interposer 100. In this example, the electrical contacts 112, 114 are formed on either side of a central opening 124 that is formed and designed to allow for physical and electrical coupling of the sensor wire 120. In this example, both electrical contacts 112, 114 are formed on the same surface of the PCB 110, however, in some examples, they may be formed on either side of the PCB 100. For example, if each electrode of the sensor wire is formed on a separate wire, they may be coupled to either side of the PCB 110. And, in this example, two electrical contacts are formed, but in some examples, three or more electrical contacts may be formed. For example, if multiple sensor wires are attached to the sensor interposer, a pair of electrical contacts may be formed for each sensor wire or each sensor electrode.

[0035] In addition to forming the electrical contacts at block 640, electrical traces are formed from each electrical contact 112, 114 to electrically couple each respective electrical contact 112, 114 to a corresponding castellation through via. In some examples, the electrical traces are serpentine to extend their length, which may reduce heat transfer from the castellation vias to the electrical contacts when the interposer is later soldered to the main PCB.

[0036] At block 650, one or more guard traces 116a-b are formed on the PCB 110. In this example, electrical traces are formed to couple the castellation through vias to one another and electrically isolate the electrical contacts. For example, referring to FIG. 3A, electrical traces are formed between the castellation through vias formed around the central opening 322 and corresponding castellation through vias formed around the PCB 310. Such traces are formed on both the top and bottom surfaces of the PCB 310, creating a guard trace that surrounds the PCB 210. Additionally, in this example, a guard trace 316c is formed between the castellation through vias formed around the central opening 322 and couples the two wrap-around guard traces 316a-b; however, the guard trace 316c is optional and may be omitted in some examples.

[0037] At block 660, the sensor wire 120 is coupled to the electrical contacts 112, 114. As described above, the sensor wire 120 may be a coaxial sensor wire 120 having two different wire materials, with the inner wire material extending beyond the outer wire material at one end of the sensor wire 120. A portion of the exposed inner wire material may be physically and electrically coupled to one of the electrical contacts 114, such as by soldering or by using a clip or other electrical coupling means. A portion of the outer wire material may be coupled to the other electrical contact 112 using any suitable electrical coupling means.

[0038] At block 670 , a suitable sensor chemistry, such as glucose oxidase, is deposited on the ends of the sensor wires 120 distal from the sensor interposer 100 .

[0039] At block 680, the sensor interposer 100 is bonded to the main PCB of the biosensor. In this example, the sensor interposer 100 is soldered to the main PCB using each of the castellation through-vias formed around the periphery of the sensor interposer. In some examples, the castellation through-vias formed around the periphery of the central opening may be soldered instead or in addition.

[0040] Although the steps of method 600 above have been described in a particular order, it should be understood that a different order may be adopted according to different examples. For example, block 630 may be performed after block 650, or block 650 may be performed before block 640 or block 630.

[0041] The foregoing description of several examples has been presented only for purposes of illustration and description, and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure.

[0042] Reference to an example or implementation herein means that a particular feature, structure, operation, or other characteristic described in connection with the example may be included in at least one implementation of the disclosure. The disclosure is not limited to the particular example or implementation so described. The appearance of the phrases "in one example," "in an example," "in one implementation," "in an implementation," or variations thereof in various places in this specification do not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described herein with respect to one example or implementation may be combined with other features, structures, operations, or other characteristics described with respect to any other example or implementation.

[0043] The use of the word "or" herein is intended to cover an inclusive and exclusive OR condition. In other words, A or B or C includes any or all of the following alternative combinations: A only, B only, C only, A and B only, A and C only, B and C only, and A and B and C, depending on the particular usage. [Explanation of symbols]

[0044] 100 Sensor Interposer 110 Planar board 112, 114 Electrical contacts 116a, 116b Guard Trace 118 Castellated through via 120 Sensor Wire 122 Polyurethane insulation 124 Opening 200 Sensor Interposer 220a~220d Castellated through vias 230a, 230b Electrical contacts 240 Guard Trace 250 Sensor Wire 252a, 252b coaxial electrode 300 Sensor Interposer 310 PCB 312, 314 Electrical contacts 316a~316c Guard Trace 322 Central opening 400 Sensor Interposer 410 PCB 412, 414 Electrical contacts 416 Guard Trace 430 Antenna 500 Wearable biosensor device 510 Main PCB 512 Surface Features 514a~514d Electrical contacts 520 Sensor Interposer 522a~522d Castellated through vias

Claims

1. a planar substrate defining a plurality of castellated through vias; a first electrical contact formed on the planar substrate and electrically coupled to a first castellated through via; a second electrical contact formed on the planar substrate and electrically coupled to a second castellation through via, the second castellation through via being electrically insulated from the first castellation through via; a guard trace formed on the planar substrate, the guard trace being electrically coupled between third and fourth through vias formed on the planar substrate, the guard trace insulating the first and second electrical contacts.

2. The guard trace is a first portion formed on the first surface of the interposer substrate, the first portion electrically coupling the third through castellation via to the fourth through castellation via; a second portion formed on a second surface of the interposer substrate, the second portion electrically coupling the third through castellation via to the fourth through castellation via; The sensor interposer of claim 1 , wherein the guard trace is formed between the first and second electrical contacts and provides electrical isolation between the first and second electrical contacts.

3. the planar substrate defines an opening between the first and second electrical contacts, the third castellation through via is formed around a periphery of the planar substrate, the fourth castellation through via is formed around the opening, and the guard trace is a first guard trace; a second guard trace formed on the planar substrate, the second guard trace being formed on the first surface of the planar substrate and having a first portion electrically coupling a fifth through castellation via to a sixth through castellation via, the second guard trace being formed on the second surface of the planar substrate and having a second portion electrically coupling the fifth through castellation via to the sixth through castellation via, the second guard trace being formed between the first and second electrical contacts and providing electrical isolation from the first and second electrical contacts; The sensor interposer of claim 1 , wherein the fifth castellated through via is formed around a periphery of the planar substrate and the sixth castellated through via is formed around a periphery of the opening.

4. The sensor interposer of claim 1 , further comprising a sensor wire electrically coupled to the first and second electrical contacts.

5. the sensor wire comprises a first wire material and a second wire material, the second wire material being coaxially formed around the first wire material, a first portion of the first wire material extending beyond the second wire material at a first end of the sensor wire; The sensor interposer of claim 4 , wherein the first portion of the first wire material is electrically coupled to the first electrical contact and the second wire material is coupled to the second electrical contact.

6. Providing a planar substrate; forming a plurality of through vias in the planar substrate; cutting a portion of the planar substrate to create an interposer substrate, the cutting including punching at least four of the through vias to create at least four castellation through vias; forming a first electrical contact on the interposer substrate and electrically coupling the first electrical contact to a first through castellation via; forming a second electrical contact on the interposer substrate and electrically coupling the second electrical contact to a second castellation through via, the second castellation through via being electrically insulated from the first castellation through via; forming a guard trace on the interposer substrate, the guard trace being electrically coupled between third and fourth through vias formed on the planar substrate and insulating the first and second electrical contacts.

7. The guard trace is a first portion formed on a first surface of the interposer substrate, the first portion electrically coupling a third through castellation via to a fourth through castellation via; a second portion formed on a second surface of the interposer substrate, the second portion electrically coupling the third through castellation via to the fourth through castellation via; The method of claim 6 , wherein the guard trace is formed between the first and second electrical contacts and provides electrical isolation between the first and second electrical contacts.

8. defining an opening in the interposer substrate between the first and second electrical contacts, the third castellation through via being formed around a periphery of the planar substrate, the fourth castellation through via being formed around the opening, and the guard trace being a first guard trace; forming a second guard trace on the interposer substrate, the second guard trace being formed on the first surface of the interposer substrate and having a first portion electrically coupling a fifth through castellation via to a sixth through castellation via, the second guard trace being formed on the second surface of the interposer substrate and having a second portion electrically coupling the fifth through castellation via to the sixth through castellation via, the second guard trace being formed between the first and second electrical contacts and providing electrical isolation from the first and second electrical contacts; The method of claim 6 , wherein the fifth castellation through via is formed around a periphery of the planar substrate and the sixth castellation through via is formed around a periphery of the opening.

9. The method of claim 6 , further comprising electrically coupling a sensor wire to the first and second electrical contacts.

10. the sensor wire comprises a first wire material and a second wire material, the second wire material being coaxially formed around the first wire material, a first portion of the first wire material extending beyond the second wire material at a first end of the sensor wire; Electrically coupling the sensor wires electrically coupling the first portion of the first wire to the first electrical contact; and electrically coupling the second wire material to the second electrical contact.

11. A planar substrate; a first electrical contact formed on the planar substrate and electrically coupled to a first castellated through via formed in the planar substrate; a second electrical contact formed on the planar substrate and electrically coupled to a second castellation through via formed in the planar substrate, the second castellation through via being electrically insulated from the first castellation through via; a guard trace formed on the planar substrate, the guard trace being electrically coupled between a third through via and a fourth through via, the third through via and the further through via being formed on the planar substrate, the guard trace insulating the first electrical contact and the second electrical contact; a sensor wire physically coupled to the planar substrate, the sensor wire including at least two electrodes, a first electrode of the at least two electrodes being electrically coupled to the first electrical contact and a second electrode of the at least two electrodes being electrically coupled to the second electrical contact; a sensor chemical disposed at a distal end of the sensor wire; and a printed circuit board ("PCB") having a plurality of electrical contacts defined on a first surface of the PCB; A wearable biosensor, wherein the sensor interposer is physically coupled to the first surface of the PCB, and the first, second, third and fourth castellated through vias are electrically and physically coupled to first, second, third and fourth electrical contacts, respectively, of the plurality of electrical contacts defined on the first surface of the PCB.

12. The wearable biosensor of claim 11 , further comprising a controller in communication with the sensor wire, the controller receiving a sensor signal from the sensor wire and determining an analyte concentration based on the sensor signal.

13. The guard trace is a first portion formed on a first surface of an interposer substrate, the first portion electrically coupling the third through castellation via to the fourth through castellation via; a second portion formed on a second surface of the interposer substrate, the second portion electrically coupling the third through castellation via to the fourth through castellation via; The wearable biosensor of claim 12 , wherein the guard trace is formed between the first and second electrical contacts and provides electrical isolation between the first and second electrical contacts.

14. the planar substrate defines an opening between the first and second electrical contacts, the third castellation through via is formed around a periphery of the planar substrate, the fourth castellation through via is formed around the opening, and the guard trace is a first guard trace; a second guard trace formed on the planar substrate, the second guard trace being formed on the first surface of the planar substrate and having a first portion electrically coupling a fifth castellation through via to a sixth castellation through via, and the second guard trace being formed on a second surface of the planar substrate and having a second portion electrically coupling the fifth castellation through via to the sixth castellation through via, the second guard trace being formed between the first and second electrical contacts and providing electrical isolation from the first and second electrical contacts; The wearable biosensor of claim 12 , wherein the fifth castellated through via is formed around the periphery of the planar substrate and the sixth castellated through via is formed around the periphery of the opening.

15. 15. The wearable biosensor of claim 14, wherein the PCB defines surface features configured to engage the openings defined in the sensor interposer planar substrate, the surface features enabling alignment between the PCB and the sensor interposer.

16. The wearable biosensor of claim 12 , wherein the sensor chemistry includes glucose oxidase.

17. The wearable biosensor of claim 12 , wherein the sensor chemistry includes chemistry configured to react with one or more of glucose, lactate, or cholesterol.

18. the sensor wire comprises a first wire material and a second wire material, the second wire material being coaxially formed around the first wire material, a first portion of the first wire material extending beyond the second wire material at a first end of the sensor wire; The wearable biosensor of claim 12 , wherein the first portion of the first wire is electrically coupled to the first electrical contact and the second wire is coupled to the second electrical contact.

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