This PDF file contains the front matter associated with SPIE Proceedings Volume 13124, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Fluorescence-based sensing has the potential for sensitive (trace), rapid and selective detection of chemical threats and is compatible with low power portable detectors that can be used in the field by military personnel, first responders, healthcare workers and those tasked with environmental monitoring. Chemical threats can include illicit drugs, toxic industrial chemicals, pesticides improvised explosive devices, and chemical warfare agents. This presentation will use practical examples to introduce different modes of fluorescence sensing, illustrate the key issues relating to solid-state detection of chemical vapours, and multivariate strategies to achieve selective chemical threat detection.

Luminescence-based sensing has been demonstrated to be a powerful method for rapid trace detection of chemical vapours. In this presentation we will describe the development of a family of perylene diimide-based sensing materials capable of undergoing photoinduced hole transfer with amine-group containing analytes, such as drugs. We will show that the choice of branched solubilising alkyl chain attached to the nitrogen atoms of the imide moiety strongly affects the solution-processed film morphology and the resulting photophysical and sensing properties. In particular, we will discuss how different film morphologies significantly affects the exciton diffusion coefficients and that when the films were used to detect N-methylphenethylamine (MPEA), a simulant of methamphetamine, there was a trade-off between a high exciton diffusion coefficient and analyte vapour uptake.

With the recent advancement in artificial intelligence and machine learning (AI/ML), the electronic nose (e-Nose) technology has improved significantly in the last decade. However, relying on the signals produced by an array of gas and volatile organic compound (VOC) sensors used as the hardware of an e-Nose, the overall performance of the system is limited by the sensor types and sensing mechanisms. The majority of the commercially available gas/VOC sensors are using metal-oxide (MOX) thin films. Although MOX sensors are relatively stable, they are extremely power-hungry. Therefore, other materials have been investigated for gas and VOC sensing. In this work, we have focused on the application of organometallic compounds as a low-cost and low-power alternative to the MOX sensors. Copper Phthalocyanine (CuPc) has been tested in both forms of a chemiresistor and an electrochemical cell. In the electrochemical design, the material presented a unique selectivity to formic acid due to a protonation reaction. However, removing contaminants from the electrolyte of an electrochemical cell is challenging and limits the repeatability of the sensor response. In contrast, in a thin-film design (chemiresistor), CuPc responds to various VOCs including ethanol, isoproapanol, and acetone, but due to the lack of the protonation mechanism, the selectivity response was not observed. Our studies on ZnPc and CoPc, also, are promising for designing an array of metal phthalocyanines (MPcs) as the hardware of an e-Nose to address the shortcomings in the MOX technology.

Ammonia gas sensors have been found widespread applications in industries, agriculture, environmental monitoring, automotive emissions control, and medical diagnosis. In this study, we report the development of a highly sensitive ammonia gas sensor using 2,4-diphenyl-6-bis(12-phenylindolo)[2,3-a]carbazole-11-yl)-1,3,5-triazine (DIC-TRZ), a common host material used in thermally activated delayed fluorescence organic light-emitting diodes, in a vertical nano-junction device structure. We also demonstrate the successful implementation of a p-type doping strategy to enhance the operation current during gas sensing. Our results indicate that DIC-TRZ is a promising material for highly sensitive room temperature ammonia gas sensing. The sensor exhibits a low detection limit in the ppb-range, fast response and recovery time, and stable operational current, making it highly potential for environmental, occupational, and personal health monitoring applications.

We developed an efficient solid-phase click reaction method to create π-conjugated-DNA amphiphilic molecules. Introducing hydrophilic DNA fragments improves the biocompatibility of π-conjugated materials and their recognition and response performance to bio-systems. π-Conjugated materials also provide optical signals for tracing and regulating the functions of DNA. This novel π-conjugated-DNA hybrid material system expands the application scope of π-conjugated materials in biomedicines. Specifically, my talk will include: (1) The development of π-conjugated-DNA amphiphilic molecules with reversible assembling properties provides a new design mechanism for the development of intelligent fluorescent bio-sensing materials; (2) Combining the encoding capability of DNA and the optical amplification properties of π-conjugated materials, amplified and highly multiplexed molecular imaging in single cells; (3) the application in light-gene combined therapy effectively improves the optical therapeutic effect of π-conjugated materials.

Understanding the influence of environmental changes on marine life is important to ecological sustainability and aqua-culture. Existing sensors are limited by size and costs that preclude widespread non-intrusive monitoring. This work reports on various organic electrochemical transistors (OECTs) to track dissolved oxygen concentration and nutrient runoff in seawater, a highly challenging matrix owing to its high ionic strength and multitude of chemical interferents. We present the dual-gate configuration that extended the device stability window by preventing undesirable reactions at the OECT channel. Specifically, the sensor achieved a detection limit of 0.5 ppm dissolved oxygen concentration in seawater. We engineer a system to monitor the correlation of oyster movement with dissolved oxygen in its environment, and it offers a new design to realize compact, highly sensitive, economical in-situ sensors for harsh marine environments.

Organic electrochemical transistors (OECTs) have found increasing applications in various emerging technologies including printed and wearable electronics, chemical and biological sensing, neuromorphic computing, and soft robotics. However, some of the challenges associated with the use of liquid electrolytes in OECTs include increased manufacturing costs for more complex and reliable encapsulation methods to prevent leakage and evaporation, as well as surface tension issues related to device miniaturization which can lead to non-uniform device operation. Though solid electrolytes have been proposed to overcome these issues, very few systems have demonstrated generality and compatibility with a wide range of state-of-the-art OMEIC materials. In this work, we present a bio-compatible, stretchable and flexible, self-healable solid-state electrolyte, that is compatible with a wide range of p- and n-type OMEICs for high performance OECTs.

We have employed organic bioelectronics using electrically responsive surfaces using charged peptides to explore the possibility of controlling cell functions. The conformation of the peptides will switch from non-bonding (OFF) to binding (ON) conformation by applying a voltage to the electrode surface through a Syn-Notch approach. In the Syn-Notch approach, we genetically modify the cells to express streptavidin on the surface and switch to a biotin-ending peptide for control. The same platform can also be used to sense ligand-receptor interactions. We have recently been part of a large effort to develop a portable sensor array for single-molecule sensing of soluble markers for pancreatic cancer2, an effort that opens up for a new paradigm in the early diagnosis of sickness. I will also discuss that the gate induced threshold shift depends largely on the gate material and provide several practical approaches to alleviate the issue, including gate encapsulation and changes to measurement protocols.

The translocation of protons across cellular membranes is crucial for various biological processes. This talk describes the development of biomimetic protein nanochannels that enable proton transport over micrometric distances. We utilize cyclic peptides that self-assemble into nanotubes, subsequently self-associating to form a hydrophilic channel wherein hydrogen bond chains, essential for proton transport, are established. This configuration emulates the proton transfer rates of natural protein channels and enhances stability in solution and under thermal stress. Our findings emphasize the potential of self-assembling peptides in bridging biological and synthetic systems for energy storage, biomedicine, and bioelectronics applications.

A nano-biocomposite film with ultrahigh photoconductivity remains elusive and critical for bio-optoelectronic applications. A uniform, well-connected, high-concentration nanomaterial network in the biological matrix remains challenging to achieve high photoconductivity. Wafer-scale continuous nano-biocomposite film without surface deformations and cracks play another major obstacle. Here we observed ultrahigh photoconductivity in DNA-MoS2 nano-biocomposite film by incorporating a high-concentration, well-percolated, and uniform MoS2 network in the ss-DNA matrix. This was achieved by utilizing DNA-MoS2 hydrogel formation, which resulted in crack-free, wafer-scale DNA-MoS2 nano-biocomposite films. Ultra-high photocurrent (5.5 mA at 1 V) with a record-high on/off ratio (1.3×10^6) was observed, five orders of magnitude higher than conventional biomaterials (~10^1) reported so far. The incorporation of the Wely semimetal (Bismuth) as an electrical contact exhibited ultrahigh photoresponsivity (2.6×10^5 A/W). Such high photoconductivity in DNA-MoS2 nano-biocomposite could be applicable in biology, electronics, and optics for innovative biomedicine, bioengineering, and neuroscience.

This work introduces a simple solution processed solid-state organic transistor sensor chip for multiplexed and selective ion sensing. The multi-ion sensing chip is capable of selectively detecting potassium (K+), sodium (Na+) and calcium (Ca2+) ions at physiologically relevant concentrations.The sensors are responsive to 4-5 decades of each primary ion. When a response from interfering ions is seen at higher concentrations, the sensors can uniquely discriminate between primary and interfering ions by a difference in the polarity of the current modulation.

Cephalopods (e.g., squids, octopuses, and cuttlefish) have captured the imagination of both the general public and scientists alike due to their sophisticated neurophysiologies, visually stunning camouflage displays, and complex behavioral patterns. Given such characteristics, it is not surprising that these marine invertebrates have emerged as exciting technological paradigms in bioinspired photonics and biomolecular electronics. Within this context, our laboratory has focused on the development of cephalopod-inspired systems and cephalopod-derived materials with unique capabilities and functionalities. In one recent research thrust, we have leveraged the cephalopod protein reflectin for engineering the optical properties of mammalian cells, while recently extending these efforts to new types of bioelectronic devices relevant for regenerative medicine applications. In another representative research thrust, we have designed and validated new concepts for adaptive infrared camouflage, while recently building upon this work for the fabrication of octopus-inspired multifunctional deception and signaling platforms. The understanding of structure-optical function relationships in cephalopods gained from such studies has suggested exciting future technological opportunities in materials science, tunable optics, and biological engineering.

Recently we studied the possibility to photostimulate living cells through functional interfaces based on organic semiconductors, polymers or molecules. After a brief review of the work done using thin films, I will describe in more details the recent use of polythiophene nanoparticles that shown the ability to recover visual acuity in lab models affected by the degeneration of photoreceptors according to Retinis Pigmentosa. The Photophysics of the nanoparticles will be presented together with a model of the interface that suggests a possible mechanism of photo-stimulation. As a last development in this research, I will report on the use of photochromic molecules as phototransducers in similar degenerated retina. The mechanism of stimulation will be described, and the recent results in vivo will be reported.

Healthcare, soft robotics, and battery management are only three examples of sensor solutions that measure the spatial and temporal distribution of temperatures and local heat flux. Thermistors and thermocouples (TCs) can both be realized by printing technologies. Combining screen printing, inkjet printing, and aerosol jet printing enables a unique combination of large-area processing and high-resolution fabrication. We have realized printed temperature sensor arrays using a printable thermoresistive polymer with several hundred individual sensors. We have recently demonstrated its application as an additional computer security feature for microprocessors [1]. As an alternative to organic sensor materials, inorganic nanomaterials are promising for thermal sensing applications based on thermoelectric principles. We have realized thermocouples as sensor arrays based on mechanically flexible substrates [3]. We used high-performance (SbBi)2(TeSe)3-based printed flexible TE materials to fabricate two types of shape-conformable TC-based temperature sensor arrays with 25 pixels.

The use of bioelectronic devices for acquiring biological information and delivering therapeutic interventions relies on direct contact with soft bio-tissues. To ensure high-quality signal transductions, the interfaces between bioelectronic devices and bio-tissues must combine signal amplification with stable and conformable contact. Organic electrochemical transistors based on mixed-conducting polymers have been developed as one of the most advanced technologies for high-performance bio-sensing. However, the rigid mechanical properties and the lack of tissue/skin adhesion from mixed-conducting polymers largely prevent the formation of such intimate and long-term stable bio-interfaces. Also, immune-mediated foreign-body response (FBR) stands as the most widely existing challenge, which can lead to the growth of fibrotic tissue at the tissue-device interface. In this talk, I will first introduce our material and device designs for introducing stretchable and tissue-adhesive properties onto mixed-conducting polymers and OECT-based biosensors. Then, to combat FBR, I will introduce a set of molecular design strategies for enhancing the immune compatibility of mixed-conducting polymers.

Radiation plays a crucial role in healthcare for both diagnostics and treatment. From imaging bones and organs to fighting cancer, ensuring the right dose at the right location is critical to minimize harm to healthy tissues surrounding the target area. This presentation introduces a novel solution for dose monitoring: RAdiation Dosimeters made from large arrays of Organic Field-Effect Transistors (RAD-OFETs). These dosimeters conform to the body, enabling high-resolution, real-time dose measurements directly on the skin. Unlike existing methods, they require minimal data processing and mimic tissue absorption, providing highly accurate readings. I will discuss the detection mechanism, sensor sensitivity, and 2D dose mapping during radiation therapy. The results reveal non-uniformities, with higher doses concentrated near the beam center. This information is invaluable for optimizing radiation treatment plans, allowing doctors to maximize target dose while minimizing damage to healthy tissue, hence leading to safer and more effective treatments for patients.

Photobiomodulation therapy (PBMT) with LLLT phototherapy has been shown to have a positive effect on the skin diseases and rejuvenation. Studies of PBM treatments have mainly used lasers and light-emitting diodes (LEDs) as light sources, and despite the advantages of organic light-emitting diodes (OLEDs), their use in PBM treatments is limited. Although OLEDs are promising next-generation wearable light source for PBMT, there is a lack of validated evidence on their of skin diseases therapy. To confirm the healing effects o OLEDs on skin diseases, we conducted a study on the therapeutic effect of OLED irradiation using animal models of atopic dermatitis and psoriasis. Our findings provide valid evidence for the healing effect of Red-OLED light sources on chronic skin diseases and suggest advances in the field of PBMT therapy.

Human-interactive displays (HIDs) have advanced the ability to visualize a spectrum of phenomena, ranging from tangible to imperceptible. Within the realm of HIDs, the role of infrared technologies stands out, with applications spanning from imaging to biomedicine. Here, we introduce a novel near infrared (NIR)-interactive synaptic display based on alternating current electroluminescence (ACEL), with a unique near infrared-responsive layer comprising from a blend of MXene and a polymer electrolyte. Our synaptic display transcends mere responsiveness to NIR exposure, by leveraging synaptic properties to visualize NIR exposure, thereby successfully realizing a neuromorphic display. Utilizing this system, we present an intelligent wound healing device through neuromorphic photothermal therapy, demonstrating its potential as a personalized treatment device. Moreover, we demonstrate the potential of this display in visualizing infrared radiation, highlighting its promising role in the ever-evolving field of HIDs.

Phosphorus, a crucial nutrient for organism development in the ecosystem, poses a significant environmental challenge due to the excessive discharge of phosphates into water, leading to widespread algae proliferation and degradation of water quality. Therefore, it is essential to develop a real-time monitoring method for determining phosphorus concentration in water. In this study, we functionalized the electrode with lanthanide-based receptors and utilized a portable potentiostat with amperometric measurement to investigate phosphate sensing within a real-time monitoring platform. This study provides a basis for portable electronics in phosphate monitoring in environmental sensing.

Optical methods offer exceptional sensitivity for probing intricate biological interactions. Here, we employ a photoactive porphyrin molecule as a sensing probe to monitor DNA hybridisation. We achieved real-time absorption spectral analysis of the DNA binding process by immobilising porphyrin on a U-bent fiber probe. Spectral shifts and intensity changes correlated with DNA binding and hybridization, respectively. Leveraging these spectral signatures, we developed a novel optoelectrical platform for DNA sensing. A porphyrin-based photodiode architecture demonstrated enhanced sensitivity, with a ~1V negative shift in threshold voltage and a threefold increase in photocurrent upon complete DNA hybridization. This platform effectively distinguishes between single-stranded and hybridized DNA, minimising false positives. The proposed optoelectrical approach holds promise for the development of cost-effective, portable DNA sensing devices.