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Main Authors: Rowe, David J., Chen, Siyu, Panainte, Mihai-Adrian, Stirling, Callum J., Dong, Pin, Bakalarz, Monika, Vizabaskaran, Hanuushah, Churchill, Glenn, Jin, Weilin, Mourkioti, Georgia, Ebert, Martin, Reed, Graham T., Faust, Saul N., Wilkinson, James S., Nedeljkovic, Milos, Owens, Daniel R., Mashanovich, Goran Z.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.01862
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author Rowe, David J.
Chen, Siyu
Panainte, Mihai-Adrian
Stirling, Callum J.
Dong, Pin
Bakalarz, Monika
Vizabaskaran, Hanuushah
Churchill, Glenn
Jin, Weilin
Mourkioti, Georgia
Ebert, Martin
Reed, Graham T.
Faust, Saul N.
Wilkinson, James S.
Nedeljkovic, Milos
Owens, Daniel R.
Mashanovich, Goran Z.
author_facet Rowe, David J.
Chen, Siyu
Panainte, Mihai-Adrian
Stirling, Callum J.
Dong, Pin
Bakalarz, Monika
Vizabaskaran, Hanuushah
Churchill, Glenn
Jin, Weilin
Mourkioti, Georgia
Ebert, Martin
Reed, Graham T.
Faust, Saul N.
Wilkinson, James S.
Nedeljkovic, Milos
Owens, Daniel R.
Mashanovich, Goran Z.
contents We report the design, fabrication and characterization of evanescent mid-infrared germanium-on-silicon waveguide sensors for therapeutic drug monitoring (TDM). TDM requires rapid and accurate quantification of serum drug levels but existing clinical assays rely on laboratory-based instrumentation that limits point-of-care deployment. In this work, tunable diode laser absorption spectroscopy was used to analyze dried samples of the anti-seizure medication phenytoin in the spectral region of $λ$ = 5.6 - 6.0 $μ$m. A limit of detection of 2.20 mg/L was achieved for extracted samples, where phenytoin was first added to human serum and subsequently isolated using liquid-liquid extraction. This limit is significantly below the therapeutic window of 10 - 20 mg/L for phenytoin, enabling detection of sub-therapeutic concentrations. At the same time, the sensor maintains a consistent dose-dependent response up to 40 mg/L, demonstrating its capability to quantify concentrations across the therapeutic window and above the upper therapeutic limit. This validates the use of silicon photonics for biomedical infrared spectroscopy for patients undergoing drug therapy, whether the serum-drug concentration is either too high or too low. These results highlight the potential of mid-IR integrated photonics to form the basis of compact, scalable platforms for point-of-care TDM.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01862
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Mid-infrared germanium-on-silicon waveguide sensor for therapeutic drug monitoring of phenytoin
Rowe, David J.
Chen, Siyu
Panainte, Mihai-Adrian
Stirling, Callum J.
Dong, Pin
Bakalarz, Monika
Vizabaskaran, Hanuushah
Churchill, Glenn
Jin, Weilin
Mourkioti, Georgia
Ebert, Martin
Reed, Graham T.
Faust, Saul N.
Wilkinson, James S.
Nedeljkovic, Milos
Owens, Daniel R.
Mashanovich, Goran Z.
Optics
We report the design, fabrication and characterization of evanescent mid-infrared germanium-on-silicon waveguide sensors for therapeutic drug monitoring (TDM). TDM requires rapid and accurate quantification of serum drug levels but existing clinical assays rely on laboratory-based instrumentation that limits point-of-care deployment. In this work, tunable diode laser absorption spectroscopy was used to analyze dried samples of the anti-seizure medication phenytoin in the spectral region of $λ$ = 5.6 - 6.0 $μ$m. A limit of detection of 2.20 mg/L was achieved for extracted samples, where phenytoin was first added to human serum and subsequently isolated using liquid-liquid extraction. This limit is significantly below the therapeutic window of 10 - 20 mg/L for phenytoin, enabling detection of sub-therapeutic concentrations. At the same time, the sensor maintains a consistent dose-dependent response up to 40 mg/L, demonstrating its capability to quantify concentrations across the therapeutic window and above the upper therapeutic limit. This validates the use of silicon photonics for biomedical infrared spectroscopy for patients undergoing drug therapy, whether the serum-drug concentration is either too high or too low. These results highlight the potential of mid-IR integrated photonics to form the basis of compact, scalable platforms for point-of-care TDM.
title Mid-infrared germanium-on-silicon waveguide sensor for therapeutic drug monitoring of phenytoin
topic Optics
url https://arxiv.org/abs/2603.01862