Sensor interposer employing castellated through-vias

1. A wearable biosensor comprising:

a sensor interposer comprising:

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 castellated through-via formed in the planar substrate, the second castellated through-via electrically isolated from the first castellated through-via; and

a guard trace formed on the planar substrate, the guard trace electrically coupled between a third through-via and a fourth through-via, the third and further through-vias formed on the planar substrate, the guard trace isolating the first and second electrical contacts;

a sensor wire physically coupled to the planar substrate, the sensor wire comprising at least two electrodes, a first electrode of the at least two electrodes electrically coupled to the first electrical contact, and a second electrode of the at least two electrodes electrically coupled to the second electrical contact; and

a sensor chemical disposed on a distal end of the sensor wire;

a printed circuit board (“PCB”) having a plurality of electrical contacts defined on a first surface of the PCB; and

wherein the sensor interposer is physically coupled to the first surface of the PCB, and wherein the first, second, third, and fourth castellated through-vias are electrically and physically coupled to respective first, second, third, and fourth electrical contacts of the plurality of electrical contacts defined on the first surface of the PCB.

2. The wearable biosensor of claim 1 , further comprising a controller in communication with the sensor wire, the controller to receive sensor signals from the sensor wire, and determine an analyte concentration based on the sensor signals.

3. The wearable biosensor of claim 2 , wherein the guard trace comprises:

a first portion formed on a first surface of the interposer substrate and electrically coupling the third castellated through-via to the fourth castellated through-via, and

a second portion formed on a second surface of the interposer substrate and electrically coupling the third castellated through-via to the fourth castellated through-via,

the guard trace formed between the first and second electrical contacts to provide electrical isolation between the first and second electrical contacts.

4. The wearable biosensor of claim 2 , wherein the planar substrate defines an opening between the first and second electrical contacts, and wherein the third castellated through-via is formed in a perimeter of the planar substrate, and the fourth castellated through-via is formed in a perimeter of the opening, and wherein the guard trace is a first guard trace, and further comprising:

a second guard trace formed on the planar substrate, the second guard trace having a first portion formed on the first surface of the planar substrate and electrically coupling a fifth castellated through-via to a sixth castellated through-via, the second guard trace having a second portion formed on the second surface of the planar substrate and electrically coupling the fifth castellated through-via to the sixth castellated through-via, the second guard trace formed between the first and second electrical contacts to provide electrical isolation between the first and second electrical contacts, and

wherein the fifth castellated through-via is formed in a perimeter of the planar substrate, and the castellated sixth through-via is formed in a perimeter of the opening.

5. The wearable biosensor of claim 4 , wherein the PCB defines a surface feature, the surface feature configured to engage with the opening defined in the sensor interposer planar substrate, the surface feature enabling alignment between the PCB and the sensor interposer.

6. The wearable biosensor of claim 2 , wherein the sensor chemical comprises glucose oxidase.

7. The wearable biosensor of claim 2 , wherein the sensor chemical comprises a chemical configured to react with one or more of glucose, lactate, or cholesterol.

8. The wearable biosensor of claim 2 , wherein the sensor wire comprises a first wire material and a second wire material, the second wire material formed coaxially 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,

wherein the first portion of the first wire material is electrically coupled to the first electrical contact, and the second wire materials is coupled to the second electrical contact.