Medical Technology & Environmental Monitoring

Pis: Prof. Dr. Karsten Seidl (Fraunhofer IMS), Prof. Dr. Daniel Erni (Universität Duisburg-Essen)

Within the framework of terahertz.NRW, THz-based concepts for the interdisciplinary cross-cutting topic of medical technology are being explored and demonstrated in shared visionary application scenarios (Use Cases). Various new actors in medicine, medical technology, and biology (Kirchner, Klaes, Klode, Krämer, Schadendorf, Schmitz, Tschulik) are being brought together with THz experts within the network.

 

THz-based medical technology represents an expansion of ongoing collaborative research, such as SFB/TRR 196 MARIE and BMBF 6GEM. It is an extremely relevant research program for terahertz.NRW in terms of developing innovative devices for theranostics, point-of-care medicine, and novel systems for THz-based hospital technology. Due to the medical focus areas of the involved clinical partners and university hospitals, the focus is primarily on applications in neurorehabilitation, tissue diagnostics, and dermatology. The demonstration is envisaged within three specific application areas: “Motion and Vital Diagnostics” (AP6.3), “Tissue Diagnostics” (AP6.4), and “Microfluidic Biosensors” (AP6.5).

 

“Motion and Vital Diagnostics” (AP6.3, Seidl, Kaiser, Kirchner, Saraceno, Tschulik): The ability of THz technology to measure distances with very high resolution in the far field, even through clothing, offers the potential for non-contact vital diagnostics [KEB/2020]. By detecting muscle movements, the control of exoskeletons and prosthetics is potentially enabled. Moreover, substance-specific frequency responses allow for multiparametric vital diagnostics, including the measurement of respiratory and pulse rates, pulse wave velocity, and glucose levels. In AP2.6 (Czylwik, Kirchner, Seidl, Weimann), system approaches for detecting muscle movements through micro-movements of the skin using THz sensors are being developed. In AP5.4 (Seidl, Benson, Kirchner), AI-based methods are being developed to infer distributed micro-movements of the skin surface, e.g., on the forearm (similar to tactile myography), and hence intended finger movements from THz far-field sensor measurements. Furthermore, fine control of the hand based on fine, superficially visible muscle movement in combination with tracking using THz tags is being investigated. These approaches will be evaluated in AP6.3 (Motion and Vital Diagnostics) for application in diagnostics, monitoring, and patient assistance for long-term monitoring of physiological data. Functional studies and comparative measurements with state-of-the-art EMG and ultrasound-based approaches, as well as alternative approaches for large-scale contact-based movement measurements of muscles, are planned.

 

“Tissue Diagnostics” (AP6.4, Hillger, Pfeiffer, Seidl, Stöhr, Klode, Schadendorff): Another visionary application of THz technology in medicine is mobile histopathology based on high-resolution THz imaging for the diagnosis of tumor tissue and neoplasms, aiming for rapid intraoperative measurement of tumor margins [ZAY/2020]. Modern functional THz approaches are currently attempting to go beyond the dominant correlation of tissue characteristics with water content to capture morphological and physical properties as well. A reflectometric and/or spectroscopic “THz endoscope” is still a significant technical challenge. In AP4.1 (Hillger, Neumaier, Pfeiffer, Benson, Kirchner, Rennings, Stöhr, Hoffmann), high-resolution THz near-field sensing is integrated into complete systems, building on novel near-field sensor architectures available from previous work at BUW (previously fiber-bound). Aspects include the development of “true-wireless” solutions and intelligent signal processing (AP5.6, Hillger, Pfeiffer, Seidl, Balzer, Brenner, Klaes, Rolfes). In the field of imaging sensors, large-scale incoherently operated THz near-field sensor arrays in conventional SiGe technology are further developed for microscopic clinical tumor margin imaging in real-time in AP4.1 (Hillger, Neumaier, Pfeiffer, Benson, Kirchner, Rennings, Stöhr, Hoffmann). The developed systems culminate in a technical demonstrator in AP5.6 (Hillger, Pfeiffer, Seidl, Erni, Brenner, Klaes, Rolfes) and can be made available to a larger user community within the network. The core application areas include the detection of malignant tissue in tumors.

 

“Microfluidic Biosensors” (AP6.5, Weyers, Klein, Hoffmann, Hofmann, Klaes): The combination of THz sensing [BRE/2018] with microsystem manufacturing processes offers interesting application fields in point-of-care diagnostics and neuroscience [ZHA/2021]. In AP4.2 (Hillger, Neumaier, Pfeiffer, Weyers, Weimann, Klaes), surface functionalizations, and in AP4.3 (Neumaier, Pfeiffer, Weyers, Benson, Klein, Weimann, Hofmann, Hoffmann), functionalized THz microsystem technologies are evaluated. Possible applications include the detection of pathogens, early detection of Alzheimer’s disease, and the detection of neurotransmitters. The approaches vary depending on the target species, from the presence of pathogens to the detection of altered proteins in Alzheimer’s disease. Subsequently, the test series will be evaluated in comparison to conventional diagnostic methods.

 

Like the planned THz applications in medical technology, THz-based environmental monitoring in terahertz.NRW also represents a significant interdisciplinary expansion of ongoing collaborative research, such as SFB/TRR 196 MARIE and BMBF 6GEM. In the field of recycling (e.g., for sorting plastics), the Fraunhofer FHR already provides mature system concepts for THz radar imaging at 80 GHz and 240 GHz, which are also used for non-contact quality inspection of food [BEC/2020]. In AP2.2 and AP3.2, these system concepts, along with imaging (MIMO) radar and reflectometry systems investigated in MARIE (250 GHz to 5 THz), are extended to a THz tomograph applicable in all network application fields (AP5.5). This builds on relevant previous work in the THz domain (Balzer, Brenner) and is intended to be used, among other applications, in AP5.5, AP6.6 at RUB (Barowski, Krämer, Rolfes, Schulz) for the first-time subterranean in-situ observation of nutrient-dependent root growth of model plants – including carrots (Daucus carota) – in indoor farming modules. Current non-contact THz plant monitoring primarily focuses on inspecting various crops [HGE/2021] in terms of properties correlated with water content [BLI/2020] [CAS/2021]. terahertz.NRW, on the other hand, aims to realize a mobile and functional multispectral, imaging THz plant monitoring (including AI-based fusion with optical image data) that captures morphology, surface texture, internal structure, as well as the dynamics of nutrient and pollutant transport in the xylem and possibly sugars and signaling molecules in the phloem of well-studied model plants such as Haller’s cress (A. halleri), Arabidopsis (A. thaliana), and poplar (Populus sp.). For this purpose, a THz near-field scanner is planned (Rennings, Krämer), which is based on azimuthally arranged passive dielectric samples, enabling access to both field applications and genetic-mechanistic research in the medium term. These will be miniaturized in AP4.1 using 3D-printed ceramic technology (Benson) and, in perspective, complemented by active integrated THz chip field probes (AP4.3). The biochemical functionalization (Delaittre) of the outstanding THz sensor (meta)-surfaces (Pfeiffer, Hillger) developed at BUW can be directly adapted to specific plant structures as well as combined with microfluidic or MEMS controllable sensor components (Hoffmann, Hofmann, Klein) for new target substances from environmental monitoring (as well as bacteria) (AP6.5). Based on previous work from MARIE on robotized THz in-room scanners (Kaiser, Saraceno, Sheikh), the possibility of outdoor monitoring of the mentioned model plants using drones will also be evaluated in AP6.6 (Kaiser, Erni, Krämer, Balzer). This involves functional THz radar imaging in the mm-wave/THz range (AP6.6, AP3.2) for topographic mapping of heavy metal inputs (Zn, Cd), physiological stress, pest damage, pests, and pollinators, as well as their spatial correlations. In this context, model-based electromagnetic studies of THz exposure on biological tissue, plants, and interacting small organisms (e.g., insects) (Erni, Balzer) are planned (AP6.6, AP5.6). In the long term, these studies should enable selective, THz radar-based observation of the dynamic biosphere immediately around the model plant (biome)