Vancomycin Exposure and Biomarker Tracking Using Real-time Monitoring of Interstitial Fluid

The goal of this observational study is to understand whether a wearable sensor (the Nutromics Sensor Device) can accurately measure drug and biomarker levels in the fluid just under the skin (interstitial fluid), instead of needing repeated blood draws, in adults admitted to hospital who are being treated with the antibiotic vancomycin or who are being monitored for signs of sepsis. The main questions it aims to answer are: * How closely do interstitial fluid levels of vancomycin match levels measured in the blood at the same time? * How closely do interstitial fluid levels of creatinine, C-reactive protein, and lactate (biomarkers linked to kidney function, inflammation, and infection severity) match levels measured in the blood? * Can the device pick up on early biomarker trends that signal a patient may be developing acute kidney injury? * How well does the device work overall, and does it perform consistently across different patients (by age, sex, ethnicity, body size, and health conditions) and over time? * Is the device safe to wear? There is no comparison group receiving a different treatment. This study looks at how well the device's readings line up with standard blood tests, not about testing a new treatment. Participants will: * Wear up to two small sensor patches on their upper arm during their hospital stay (up to 5 days), with each patch replaced every 48 hours * Have blood samples taken as part of their routine care so results can be compared * Have their medical records reviewed 30 days after finishing the study to check on their health outcomes