Infrared photonics for healthcare: A roadmap for proactive and predictive health management

The field of infrared (IR) photonics is currently undergoing remarkable progress, moving rapidly towards practical sensing applications demanded by medical therapy and diagnostics (theranostics). The Developments can be divided into three main categories: (i) novel devices and measurement concepts including advanced updates of classical approaches that push medical sensing into the spotlight; (ii) new demonstrations of photonic integrated circuit (PIC-)based IR devices enabling highly miniaturized sensors for point-of-care application as well as medical and wellness wearables; and (iii) technologically-mature IR demonstrators that enable first medical sensing and treatment applications. This roadmap paper provides a consolidated overview of this highly dynamic and interdisciplinary research field with a focus on the major roadblocks that limit the widespread adoption of IR photonics in large-scale medical diagnostics. Special attention is given to the ambivalence between the molecular-level spectroscopic interpretation and a broader health-state assessment, highlighting the need for a common framework. Additionally, the paper discusses the critical importance of unified measurement standards, calibration protocols, and medical certification processes to ensure the validity of experimental results, reproducibility, and clinical trust, particularly when novel experimental techniques and AI algorithms are involved. Perspectives from major past and current contributors to application-oriented IR photonics will be provided.

💡 Research Summary

The paper presents a comprehensive roadmap for translating infrared (IR) photonics into practical healthcare solutions, with a focus on proactive and predictive medicine (theranostics). It begins by outlining the rapid advances in IR sources, detectors, and spectroscopic techniques, and then structures the field into three major development streams.

1. Novel Devices and Measurement Concepts – This section reviews next‑generation FTIR, Raman, and dispersion spectroscopy approaches that push sensitivity, resolution, and speed while dramatically reducing power consumption. Key innovations include thermal emitters combined with pyroelectric detectors (the “spectroscopic twin” concept), background‑free field‑resolved IR spectroscopy, and low‑dissipation quantum cascade lasers (QCLs). These advances enable reagent‑free analysis of biofluids, non‑invasive glucose monitoring, and rapid point‑of‑care (POC) diagnostics.

2. Photonic Integrated Circuit (PIC)‑Based IR Sensors – The authors detail the migration of mid‑IR functionality onto silicon, GaSb, and other semiconductor platforms. Integrated waveguides, metasurfaces, and on‑chip QCLs are combined to produce compact, low‑voltage, and mass‑producible sensors. Hybrid PICs that co‑integrate electronics and photonics are highlighted as the enabling technology for wearable health monitors and distributed diagnostic networks. Specific examples include MEMS‑miniaturized FTIR spectrometers, broadband beam splitters, and monolithic MIR PICs that can host multiple sensing functions on a single chip.

3. Technologically Mature Demonstrators – This part surveys the current state‑of‑the‑art applications that have reached clinical or near‑clinical validation. Topics cover FTIR‑based urine and saliva analysis, breath‑omics for disease screening, infrared hyperspectral imaging of tissues, super‑resolution mid‑IR microscopy for neurodegenerative disease biomarkers, and detection of micro‑ and nanoplastics in biological samples. A notable contribution is the introduction of “InfraRed‑omics,” an integrative framework that links molecular fingerprint data to holistic health phenotypes using explainable AI (XAI).

Beyond the technical categories, the roadmap emphasizes four cross‑cutting challenges that must be addressed for large‑scale adoption:

• Standardization and Calibration – The lack of international metrological standards for IR biomedical measurements hampers reproducibility. The authors propose a hierarchical calibration chain (reference gases → detector → algorithm) and call for community‑wide consensus on data formats and reporting metrics.

• Regulatory and Certification Pathways – Translating IR devices into in‑vitro diagnostic (IVD) products requires alignment with FDA, EMA, and other regional bodies, as well as compliance with data‑privacy regulations (GDPR, HIPAA). The paper outlines a staged certification strategy that integrates safety testing, clinical validation, and post‑market surveillance.

• AI Integration and Trustworthiness – While machine‑learning models can extract complex patterns from high‑dimensional IR spectra, the authors warn that opaque “black‑box” approaches risk clinical mistrust. They advocate for XAI methods, rigorous cross‑validation, and transparent reporting of uncertainty to satisfy both clinicians and regulators.

• Energy Efficiency and Sustainable Manufacturing – For population‑scale screening and continuous wearables, power budgets must be minimized. The roadmap calls for low‑threshold QCLs, thermoelectric cooling, and scalable silicon photonics foundry processes to achieve cost‑effective, environmentally sustainable production.

In its concluding remarks, the paper argues that only by simultaneously advancing device physics, integrated photonic architectures, robust standards, and ethical‑regulatory frameworks can IR photonics become a cornerstone of future healthcare. When these elements converge, IR‑based platforms will enable rapid, reagent‑free diagnostics, continuous health monitoring, and data‑driven personalized interventions, ultimately shifting medicine from reactive treatment to proactive health management.