Nanosized bioelectronic detecting interfaces have been the privileged pathway to single-molecule detections so far. However, while giving access to rarer events, this near-field approach is unsuited to detect at concentrations lower than nanomolar because of the diffusion-barrier issue. Namely, it will be statistically extremely improbably for a nanometric interface to encounter the target analyte if the solution is too diluted.

At the same time, biomarkers are becoming the preferred highway toward early diagnosis of progressive diseases, such as tumors or neurodegenerative syndromes. When it comes to infective diseases the immunometric direct detection of a pathogen (instead of its genome) is a faster way, as it requires no sample pretreatment. The possibility of detecting a marker (proteins, genomic strands as well as whole viruses or bacteria) in a peripheral biofluid such as blood or even saliva, makes the process also minimally invasive. The sooner the detection is, the earlier the diagnosis will be, the easier for a clinician to fight the battle against a disease, is. Nowadays there is the possibility to detect a single strand of a mutated gene for the early diagnosis of tumours or to detect a single copy of a viral DNA. Still a commercial system that can reliably detect a single-proteins in a sample of 0.1 ml of a real biofluid, is not available.

Large-area (μm^2 - mm^2 wide) bioelectronic transistors are perceived as unsuited due to the irrelevant footprint of a single molecule on a much larger detecting interface. Indeed, detecting such an event would be like spotting the wave generated by a single droplet of water falling on a one-kilometer-wide pond. However, many field-effect large-area biosensors have been shown to detect at limit-of-detection below femtomolar, being also naturally suited for point-of-care applications. In this lecture the field is reviewed, illustrating device architectures, materials used, and target analytes that can be selectively detected. The sensing mechanisms and the amplification effects enabling the large-area bioelectronic sensor to detect at the physical limit are also detailed.

Use of light for selective and spatio-temporally resolved control of cell functions (photoceutics) is emerging as a valuable alternative to standard electrical and chemical methods. We propose the use of organic semiconductors as efficient and biocompatible optical transducers, and we focus in particular on breakthrough applications in the field of regenerative medicine. Devices able to selectively and precisely modulate the fate of living cells upon visible light will be presented and critically discussed. Examples of practical applications include optical modulation of the activity of both excitable and non-excitable cells, control of essential cellular switches like transient receptor potential channels and other cationic channels, as well as effective modulation of intracellular calcium signalling for precise control of cell metabolic processes.

As a representative example with a high translational potential, we describe here in detail a biointerface to gain optical control of Endothelial Colony Forming Cells, which represent the only known Endothelial Progenitor Cell subset and are valuable candidates to induce revascularization of ischemic tissues. We demonstrate that polymer-mediated optical excitation induces a robust enhancement of lumen formation in vitro. We identify the pathways leading to this effective enhancement in Endothelial Colony Forming Cells network formation, as due to light-induced activation of the non-selective Transient Receptor Potential Vanilloid 1 (TRPV1) cation channel. Moreover, we show that polymer-mediated optical excitation induces a long-lasting increase in intracellular calcium ions concentration, [Ca²⁺]_i. Pharmacological and genetic manipulation reveals that the Ca²⁺ response to light is triggered by extracellular Ca²⁺ entry through TRPV1, whose activation requires the non-toxic production of reactive oxygen species at the interface between the photoactive material and the cell membrane.

Our results represent, to the best of our knowledge, the first report of use of polymer-based optical modulation to restore cardiac function in vitro, by modulating cellular activities of one of the main characters involved in cardiac repair.

Organic bioelectronics is an emerging interdisciplinary field, encompassing organic electronic interfaces operating in physiological conditions hand-in-hand with biological systems. These interfaces are mostly based on conjugated polymers that have emerged as ideal materials due to their biocompatibility, tissue-like mechanical properties, and their ability to simultaneously conduct electronic and ionic currents. Importantly, these properties can be tailored to meet the requirements of different types of human tissue with relatively easy methods – e.g. by chemical synthesis or by simply mixing wet solutions of conjugated polymers with other additives. These profound advantages enabled the development of organic bioelectronic devices that push the boundaries in a range of applications, from brain interfaces to in vitro diagnostics and tissue engineering. Here we will present the development of multifunctional bioelectronic interfaces to monitor and control cellular activity with conventional electrical measurements, in vitro. First, the development of a free standing, photosensitive platform based on a combination of conjugated polymers will be presented. This platform is able to control wirelessly the activity of primary cortical neurons with white light at low intensity. Later on, the development of 3D mesoporous polymer scaffolds for growing human stem cells tissue will be presented. These structures are made from composites of conjugated polymers and are able to recapitulate 3D tissue-like environments as well as exhibit multifunctional properties (i.e low young modulus, good electrical conductivity and photo-sensitivity). The pore size/network inside the scaffold can be also tailored by changing the amount and the nature of the cross-linker, which can in turn control stem cell growth rates and size. These biomimetic, multifunctional 3D structures are addressed electrically to form 3D electrodes that allow for monitoring human stem cell proliferation rates with electrical impedance measurements. Finally we will present preliminary results on how we can leverage the properties of multifunctional scaffolds to control cell fate and differentiate “naïve” stem cell tissue to neurons via chemical, electrical and light stimulation.

In vitro monitoring of electrogenic cells represents a very interesting approach in different scientific fields such as neuroengineering, pharmacology, and potentially also translational medicine. One of the key aspects of all cellular cultures, and this is particularly true for standard electrogenic cell cultures, as well as for cardiac organoids and neurospheroids, is their complexity, mainly due to the different kinds of both chemical and electrical signals that characterize their response to external stimuli and that ultimately govern their behavior. During the past 50 years, this extraordinary complexity pushed the research community to develop increasingly complex devices and tools with the idea of fully exploiting all the different aspects of these multiparametric systems. To the aim of providing a simple and integrated approach for the study of in vitro electrogenic cultures, and thus offer a potentially simpler solution to the monitoring of different cellular features, we present here an organic transistor-based device capable of measuring two of the most important cellular parameters, namely the electrical and the metabolic activity, using the ultra-sensitive Organic Charge Modulated FET (OCMFET). The OCMFET, thanks to its peculiar structure and outstanding versatility, can be conveniently engineered in order to meet the desired sensing needs, ultimately allowing to obtain multisensing and multisite tools capable of simultaneously recording the aforementioned parameters using a single type of organic transistor, differently from other existing approaches. The device, called Micro OCMFET Array (MOA), has been tested using primary cardiac rat myocytes, and allowed to evaluate the metabolic and electrical variations that occur upon the administration of different drugs. Although preliminary, these results demonstrate the very interesting potentials of organic transistors in this highly complex and multifaceted scientific field, thus laying the basis for the development of a multi-sensing tool for the in vitro monitoring of cell aggregates. As a future perspective, the possibility of obtaining MOA devices with 3D recording sites will also be addressed. This capability, together with the already-mentioned versatility of the system, may represent a potentially game-changing feature within the rising field of in vitro organoid studies.

The ability to operate in aqueous environments makes poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, based organic electrochemical transistors (OECTs) excellent candidates for a variety of biological applications. Current research in PEDOT:PSS based-OECTs is primarily focused on improving the conductivity of PEDOT:PSS film to achieve high transconductance (g_m). The improved conductivity and electronic transport are attributed to the formation of enlarged PEDOT-rich domains and shorter PEDOT stacking, but such a change in morphology sacrifices the ionic transport and, therefore, the doping/de-doping process. Additionally, little is known about the effect of such morphology changes on the gate bias that makes the maximum g_m, threshold voltage, and transient behavior of PEDOT:PSS based OECTs. Here, we tune the molecular packing and nanostructure of PEDOT:PSS films using ionic liquids as additives, namely, 1-Ethyl-3-methylimidazolium (EMIM) as cation and anions of chloride (Cl), trifluoromethanesulfonate (OTF), bis(trifluoromethylsulfonyl)imide (TFSI), and tricyanomethanide (TCM). We demonstrate that an optimal morphology is realised using EMIM OTF ionic liquids that generate smaller fibril-like PEDOT-rich domains with relatively loose structures. Such optimal morphology improves ion accessibility, lowering the gate bias required to completely de-dope the channel, and thus enabling to achieve high transconductance, fast transient response and at lower gate bias window simultaneously.

Interfacing electronics and biology opens the need for materials having suitable electrical and mechanical properties, as transporting both ions and electrons and soft mechanical properties. Among all materials, polythiophene conjugates emerged for their higher biocompatibility, ionic as well as electronic conduction, and optical properties in the visible range. Remarkable results have been obtained interfacing polythiophenes-based transistors and actuators with mammalian cells, as well as plants, to a lower extent. However, the phenomena occurring at the interface with aqueous environment are yet to be characterized and understood. In particular, electrochemical doping/de-doping results in volume change, which can diminish device performance and reduce stability. However, the possibility to electrically address and modulate on-demand the volume can pave the way for a new class of devices, where both mechanical stimulation and mixed conduction play together. Here, we investigate the doping/de-doping behaviour of a new class of polythiophene based materials, conjugated to ethylene glycol side chain of different lengths. According to previous publications, our findings show that the electrochemical doping involves materials volume change in aqueous environment. Additionally, we demonstrate that the amount of volume change depends on the ionic strength of the solvent, thus further investigations are being carried out to elucidate the fundamental processes involved in the recorded large volume changes. The ionic intercalation is also influencing the mechanical properties of the doped as well as the de-doped material, as the mechanism is not fully reversible. We report also the mechanical characterization of the material family as a function of the ionic strength of the solvent.

Our findings deterministically correlate the mechanical properties, the volume changes and the doping state of the material, laying the basis for the development of electrically addressable devices. This class of material and devices has a great potential interest for bioelectronic applications, as it accounts for ionic/electronic conduction and on-demand modification of stiffness, emerging as a smart platform for mammalian and plant cell stimulation and monitoring.

Conjugated polymers have found a fertile field of application in bioelectronics. Their ability to change doping state after injection of ions from an electrolyte (the so-called electrochemical doping process) makes them versatile transducers of ionic-to-electronic conduction. This process is at the heart of most bioelectronic devices. I will present a device-level description of this process, where electronic and ionic carrier injection/extraction is followed by bipolar transport and compensation, and discuss the role of extrinsic processes including electrolysis and charge transfer to species in the electrolyte. Experiments and simulations will show the relative importance of these processes in typical materials systems.

A cornerstone of clinical management for many neurological disorders is recording and manipulating pathologic electrical brain signals. However, limitations in the types and resolution of neural activity that can be acquired continue to exist, and use of current neural interface devices often carries the risk of significant side effects. Here, we demonstrate the capacity for soft, organic electronics to facilitate large-scale recording and closed loop neuromodulation of brain signals. We are able to record high spatiotemporal resolution intracranial and scalp electroencephalography (EEG) from human subjects. We have innovated devices to acquire such signals from the developing rodent brain, tracking physiologic developmental trajectories and identifying networks involved in emergence of epileptic activity. We have leveraged this data to create fully implantable closed-loop devices that can suppress pathologic activity in epileptic networks. These applications of organic electronics highlight the potential of such materials and devices to benefit diagnosis and therapy of neurological disorders.

Conjugated mixed conductors have attracted much attention lately as soft materials with applications in bioelectronics, energy storage and brain-like computing. In addition to the well-known PEDOT:PSS blend, new families of polymers with glycolated side-chains have been recently developed with promising performance. Interestingly, details of how charge transport occurs and how it’s related to ionic transport are still not well understood in both PEDOT:PSS blends and newer materials. This lack of understanding hinders the rational design of the next generation of high-performance materials. In this talk I will show the result of experiments that suggest that while its role in ion transport is well understood, the insulating PSS phase also plays an unexpected role in electronic transport in PEDOT:PSS blends, suggesting new design rules to control electronic transport in these materials. Furthermore, I will show how the microstructure of glycolated polymers must show a balance between aggregates and disordered regions in order to ensure optimal electrochemical performance. Finally, I will show how understanding these materials properties is instrumental in understanding how they operate and the limits of their performance.  

Thiophene-based trimers is a new class of organic electronic molecular units, which enable the organization and polymerization of conjugated structures within living biological systems and inside operating electronic devices and systems. The trimers can be equipped with side groups that targets and promotes coupling to specific surfaces and (bio-)chemical cues making self-organization and -assembly of organic bioelectronics possible in a novel manner. The chemical and physical fundamentals of the trimers, the route of polymerization, and their performance while operating in neuromorphic and in vivo-manufactured bioelectronics will be reported. Specifically, neuromorphic systems based on organic electrochemical transistors including the trimers will be described along with bioelectronic systems formed inside living plants, cells and animal models. Our findings promise for radically new ways of forming bioelectronic systems in living systems, which mimicks the structures and functions of the signaling of biology.

Electronically controlled drug delivery offers the potential for precisely controlled release of pharmaceuticals when and where they are needed. This concept could lead to more effective therapies with minimal side effects and minimal requirements for user input. This talk will overview recent advances in electronic drug delivery devices that leverage the favorable mixed conducting properties of organic electronics.  This will include advances in engineering and applcations as well as fundamental insights into device physics and optimal material properties.  The talk will conclude with an perspective on criticals areas for future developments in order to realize the full potential for electronic drug delivery.

The necessity for quick, reliable, easy-access and low-cost devices for healthcare assessment is currently attracting a great deal of interest and the market for such products is growing rapidly. This contribution deals with a novel class of Point-of-Care devices based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) Organic Electrochemical Transistors (OECTs).

OECTs are promising electronic platforms that have recently attracted increasing interest, since they can provide intrinsic signal amplification without the need of a freestanding reference electrode, they can operate at low power (< 100 μW) and can be easily miniaturized and adapted to non-flat, flexible and even textile substrates. In addition, providing high sensitivity together with biocompatibility and low-cost, could be proposed as analytical tools for the reliable detection of a wide range of low concentration analytes even in biological fluids.

All PEDOT:PSS OECTs can be used as chemical sensor for the detection of redox analytes able to undergo oxidation at PEDOT:PSS, such as ascorbic acid, dopamine, adrenaline or uric acid. The redox molecules react with PEDOT:PSS by extracting charge carriers from the transistor channel, and consequently an increase of analyte concentration leads to a decrease of the absolute value of the drain current that is used as the analytical signal[1].

On the other hand, the selectivity issue must be addressed to allow the widespread use in real-life applications, through a proper functionalization of the gate electrode with molecules able to selectivity interact with the target analyte [2]. In this regard glucose and lactate biosensors have been fabricated by immobilizing the enzyme glucose oxidase or lactate oxidase on the gate surface; moreover pH or chloride sensors have been described, entrapping iridium oxide or silver/silver-chloride nanoparticles on the PEDOT polymer, thus developing a two terminal sensor able to work without an external gate electrode.

As an example of application, a smart bandage has been realized for the real-time monitoring of wound pH, which has been reported to correlate with the healing stages, thus potentially giving direct access to the wound status without disturbing the wound bed. The fully textile device is realized by integrating a sensing layer, including the two-terminal pH sensor made of a semiconducting polymer and iridium oxide particles, and an absorbent layer ensuring the delivery of a continuous wound exudate flow across the sensor area[3].

Many chemotherapeutic agents are limited in their success in cancer treatment due to poor delivery and systemic toxicity. A way to efficiently interfere with cancer growth and to reduce tumor recurrence is local chemotherapy. This is especially of interest for the treatment of high grade brain tumors, which remain an unmastered clinical challenge due to high recurrence rates and frequently occurring resistance to standard chemotherapeutics.

We present miniature organic electronic devices for drug delivery able to administer chemotherapeutics via electric control with high spatiotemporal precision.¹  Incorporated in these devices are anionic hyperbranched polyglycerol membranes, forming an ion selective matrix of multiple fixed negative charges.² Through this polymeric membrane, drugs electromigrate in an electric field towards a target of choice. Here, a free-standing capillary prototype was used for proof-of-principle experiments.

The performance of these bioelectronic devices, called chemotherapeutic ion pumps (chemoIPs),  was characterized with voltammetric and amperometric measurements and tested in different brain tumor models with increasing complexity (cell culture to short-term in vivo model). ChemoIP-mediated drug delivery was compared to computer simulations. Additionally, the influence of Gem on neural and cancerous brain cultures was analyzed with whole proteome analysis. The treatment efficiency was analyzed based on cell death, suppression of tumor growth and drug distribution.

ChemoIPs enable drug delivery with pmol*min^-1 precision at currents in the nano-ampere range. The further application of this electrical and temporal control was shown in the cell monolayer and 3D cell culture, triggering the disintegration of targeted brain tumor spheroids among chemoIP treatment. Via whole proteome and cell viability analysis we confirmed that Gem efficiently kills brain tumor cells, while neuronal cultures are unaffected. Additionally, we show preliminary results indicating that the chemoIP treatment significantly induces tumor shrinkage in a short-term in vivo brain tumor model.

The here exemplified electrically-driven drug delivery via chemoIPs is a drug administration method that can serve as basis for further implant development, which has the potential to increase the efficacy of chemotherapy due to highly-targeted and locally-controlled drug delivery.

Recently emerged on-skin electronics with applications in human-machine interfaces and on-body healthy monitoring call for the development of high-performance skin-like electrodes and semiconducting polymers. The development of waterproof and breathable membranes that can provide a high level of protection for human skins and a comfortable contact between electronics and human skin are the pressing demands for on-skin electronics. However, major challenges remain, such as the limited mechanical durability and permeability of gas and liquid, hindering long-term stability and reusability. Therefore, it is highly desirable to develop a new type of skin-breathable and waterproof on-skin electronics. Herein, we report a fibrous electrolyte containing polymer matrix and ionic liquid by electrospinning method, which is highly robust, breathable, waterproof, and conformal with human skin, after bonding a parylene layer between fibers. The improvement of electrical conductivity of both electrodes and organic semiconducting polymer, and ionic conductivity of fibrous electrolyte were demonstrated. Serving as fibrous substrate and electrolyte of organic electrochemical transistors (OECTs), a high transconductance of ~0.8 mS, fast response time of 60 ms and stability over pulsing and time (~1000 cycles and 30 days) were achieved. The waterproof and breathable capabilities of fibrous OECTs enable comfortable contact after attaching to human skin, which can also reduce the interfacial impedance to achieve local amplification of the high-quality electrocardiography signals (SNR of 21.7 dB) even in skin squeezed state or after one week. These results indicated that our fibrous OECTs have huge potential for versatile on-skin electronics such as non-invasive medical monitoring, soft sensors, and textile electronics.

Wearable and Internet of Things technologies represent a potentially high-impact breakthrough for next future strategies targeting improved occupational safety and health management. In particular, they could enable the real-time monitoring of health-related and environmental information to the wearer, emergency responders and inspectors regarding air pollution, indoor air quality, aerosol exposure and detection of biothreat agents in the workplace. Among hazardous gaseous compounds causing severe health issues, ammonia shows a high solubility in aqueous environment and the contact with its vapours immediately causes irritation to eyes, mucous membranes and whole respiratory system, while exposure to high concentrations can lead to life-threatening conditions. This contribution describes the development of a wearable gas sensor for NH₃ detection at room temperature [1] based on the organic semiconductor poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), electrochemically deposited iridium oxide particles (IrOx Ps) and a hydrogel film based on agarose that assists the sensing mechanism, which relies on electrochemical gating [2-5]. The working principle significantly differs from most of the state-of-the-art NH₃ gas sensors and originates from the potentiometric response of IrOx Ps, which are embedded within the organic semiconductor and respond to local pH variations in the hydrogel, thus modulating the doping state of the semiconductor. The hydrogel interface, where the gaseous analyte reversibly absorbs and dissolves producing pH variations, is actually the key component of the sensor structure for the achievement of a reversible and selective response. Its composition, acid-base properties and morphology were finely optimized to obtain self-healing properties, as well as the desired porosity, adhesion to the substrate and stability to humidity variations. Thanks to the reliability of the analytical response, the simple two-terminal configuration and the low power consumption (around 0.1 mW), the PEDOT:PSS/IrOx Ps/hydrogel sensor was realised on a flexible plastic foil and successfully tested in a wearable configuration with wireless connectivity to a smartphone. The wearable sensor showed stability to mechanical deformations and good analytical performances, with a sensitivity of 60 ± 8 μA decade^-1 in a wide concentration range (17 – 7899 ppm), which includes the safety limits set by law for NH₃ exposure, e.g. 25 ppm averaged over an eight-hour workday and 35 ppm for short-term exposure (according to the National Institute for Occupational Safety and Health).

Organic electrochemical transistors (OECTs) have recently attracted attention due to their high transconductance, low operating voltage, and compatibility with aqueous solutions for broad bio-sensing applications. Poly-3,4-ethylenedioxythiophene:poly-4-styrenesulfonate (PEDOT:PSS) is a typical material acting as the active channel layer in OECTs. However, the poor electrical conductivity of pristine PEDOT:PSS diminish the lifetime and restrict the application scope of the electronic device systems. Although some additives in PEDOT:PSS have been proposed to enhance the conductivity, those additives are either toxic or not proved to be biocompatible. Herein, a biocompatible ionic liquid is proposed as an effective additive to enhance the performance of PEDOT:PSS based OECTs. The influence of the ionic liquid on the conductivity, morphology, and the redox process of PEDOT:PSS during electrochemical doping/de-doping processes are explored. The PEDOT:PSS/the ionic liquid (PEDOT:PSS mixed with the ionic liquid) film as OECT channel layer exhibits enhanced transistor characteristics, such as higher transconductance [the normalized gm/(Wd/L) are 22.3 ± 4.5 mS μm-1], a high μC* product [283.80 ± 29.66 F cm-1 V-1 s-1], fast response times [40.57 μs for the device (W/L = 100 μm/10 μm, d = 69 nm)] and excellent switching cyclical stability [> 95% retention after 5000 cycles]. In addition, flexible and biocompatible OECTs are designed using the PEDOT:PSS/the ionic liquid for electrophysiological (ECG) signals acquisition. These OECTs showed robust performance against physical deformation and successfully recorded ECG signals from the heart of a volunteer. Furthermore, an on-skin electronic device consisting of PEDOT:PSS/the ionic liquid based OECT and sensing component is demonstrated to monitor full-range human motions. In conclusion, PEDOT:PSS/the ionic liquid based devices exhibit promising potential for skin-based physiological signals monitoring. 

As our understanding of the brain’s physiology and pathology progresses, increasingly sophisticated technologies are required to advance discoveries in neuroscience and develop more effective approaches to treating neuropsychiatric disease. To facilitate clinical translation of advanced materials, devices, and technologies, all components of bioelectronic devices have to be considered. Organic electronics offer a unique approach to device design, due to their mixed ionic/electronic conduction, mechanical flexibility, enhanced biocompatibility, and capability for drug delivery. We design, develop, and characterize conformable organic electronic devices based on conducting polymer-based electrodes, particulate electronic composites, high-performance transistors, conformable integrated circuits, and ion-based data communication. These devices facilitate large-scale neurophysiology experiments and have led to discovery of a novel cortical oscillation involved in memory consolidation as well as elucidated patterns of neural network maturation in the developing brain. The biocompatibility of the devices also allowed intra-operative recording from patients undergoing epilepsy and deep brain stimulation surgeries, highlighting the translational capacity of this class of neural interface devices. In parallel, we are developing the high-speed conformable implantable integrated circuits and embedded acquisition and storage systems required to make high channel count, chronic neurophysiological recording from animals and human subjects possible. This multidisciplinary approach will enable the development of new devices based on organic electronics, with broad applicability to the understanding of physiologic and pathologic network activity, control of brain-machine interfaces, and therapeutic closed-loop devices.

Transmembrane proteins (TMPs) are Nature’s biorecognition, sensing, and transduction elements and critical components in biomimetic sensing. However, they are among the most challenging biomolecules to integrate into biosensors because they require a lipid bilayer to remain functional. Successful bilayer and TMP integration with bioelectronic devices would enable new capabilities in in vitro biosensing and biological actuation. To date, reconstitution of lipid bilayers onto sensing surfaces requires significant optimization of the abiotic/biotic interface. Nonetheless, current hybrid biotic-abiotic devices show great promise in biosensing, but even more so if arrays of TMPs tailored to sense specific targets could be produced. Such scale up is necessary for rapidly identifying the most sensitive protein sensors, providing a myriad of sensing elements that can monitor a variety of targets simultaneously, or producing enough data to enable machine learning approaches that can extend beyond biosensing into bioanalytical applications.

Our team has developed several approaches to integrate TMPs into supported lipid bilayers that functionalize organic bioelectronic devices. In this presentation, I will cover two methods. First, I will describe a technique to harvest membrane vesicles from live cells and using them to coat a surface of a bioelectronic device. Once formed, they serve as an authentic replica of the plasma membrane from a variety of cell types. I will describe two sensing examples using this approach: 1) measurements of ion channel activity for drug screening applications and 2) sensing of host-pathogen interactions, in particular, virus entry processes that lead to host cell infection. For the second approach, we use cell-free synthesis of proteins, in which cellular extracts are used to synthesize transmembrane proteins directly into lipid bilayers that coat the sensing surface. I will provide an example of ion channel sensing using TMPs formed by this approach.

Our goal is to build TMP arrays on bioelectronic devices that sense their functions and activity levels using the dual modality of electronic and optical means. The criticality of dual mode data collection is that, for transporters and ion channels, electrical means can be used label-free to read out flux of material across the membrane. Optical approaches offer the possibility to simultaneously obtain confirmation of folding with protein folding reporters, as well as obtaining structural information. Combining all these features into one platform offers a wealth of possibilities for many biosensing and bioanalytical applications and could be used to understand how the properties of the membrane influence the activity of TMPs.

Organic electrochemical transistors (OECTs) have been demonstrated in a wide range of applications such as analyte detection, neural interfacing, impedance sensing and neuromorphic computing. Majority of OECTs use PEDOT:PSS and liquid electrolytes. In this talk, I will discuss the development of conjugated polyelectrolytes (CPEs) as semiconductors for OECTs and the working mechanism of CPE-based OECTs. CPEs are materials that comprise a conjugated polymer backbone and charge-functionalized alkyl side chains and counterions. The anionic CPE poly[2,6-(4,4-bis-potassium butanylsulfonate-4H-cyclopenta-[2,1-b;3,4-b’]- dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBTSO3K, or CPE-K) is part of a unique class of organic semiconducting polymers that are soluble in water and become doped in the presence of a proton source. CPE-based OECTs can operate in either the accumulation or depletion mode. We investigate the impact of the alkyl chain lengths and the conjugated backbone on the optical property, the film morphology, the electronic and ionic conductivity and the transconductance in OCETs.