We have developed a stretchable microneedle electrode array (sMEA) to stimulate and measure the electrical activity of muscle across multiple sites. The technology provides the signal fidelity and ...spatial resolution of intramuscular electrodes across a large area of tissue. Our sMEA is composed of a polydimethylsiloxane (PDMS) substrate, conductive-PDMS traces, and stainless-steel penetrating electrodes. The traces and microneedles maintain a resistance of less than 10 kQ when stretched up to a ~63% tensile strain, which allows for the full range of physiological motion of feline muscle. The device and its constituent materials are cytocompatible for at least 28 days in vivo. When implanted in vivo, the device measures electromyographic (EMG)activitywith clear compound motor unit action potentials. The sMEA also maintains a stable connection with moving muscle while electrically stimulating the tissue. This technology has direct application to wearable sensors, neuroprostheses, and electrophysiological studies of animals and humans.
Ophthalmic drug for the anterior chamber diseases are delivered into tears by either eye drops or by extended release devices placed in the eyes. The instilled drug exits the eye through various ...routes including tear drainage into the nose through the canaliculi and transport across various ocular membranes. Understanding the mechanisms relevant to each route can be useful in predicting the dependency of ocular bioavailability on various formulation parameters, such as drug concentration, salinity, viscosity, etc. Mathematical modeling has been developed for each of the routes and validated by comparison with experiments. The individual models can be combined into a system model to predict the fraction of the instilled drug that reaches the target. This review summarizes the individual models for the transport of drugs across the cornea and conjunctiva and the canaliculi tear drainage. It also summarizes the combined tear dynamics model that can predict the ocular bioavailability of drugs instilled as eye drops. The predictions from the individual models and the combined model are in good agreement with experimental data. Both experiments and models predict that the corneal bioavailability for drugs delivered through eye drops is less than 5% due to the small area of the cornea in comparison to the conjunctiva, and the rapid clearance of the instilled solution by tear drainage. A contact lens is a natural choice for delivering drugs to the cornea due to the placement of the contact in the immediate vicinity of the cornea. The drug released by the contact towards the cornea surface is trapped in the post lens tear film for extended duration of at least 30min allowing transport of a large portion into the cornea. The model predictions backed by in vivo animal and clinical data show that the bioavailability increases to about 50% with contact lenses. This realization has encouraged considerable research towards delivering ocular drugs by contact lenses. Commercial contacts are, however, not ideal for drug delivery due to the short release durations which may necessitate wearing multiple lenses each day, reducing the viability of this approach. Recent research has focused on designing contacts that retain all critical properties while increasing the release durations to a few hours or a few days. Beagle dog studies with contact lenses containing vitamin E nanobarriers to attenuate drug transport have shown promising results. Human studies using contacts for drug delivery have also been conducted for allergy therapy but drug eluting contacts are not available in the market for any therapy.
Display omitted
•Mechanistic model developed for tear drainage from the eyes•Mechanistic models developed for transport across cornea and conjunctiva•Individual models integrated into a tear dynamics model•Mechanistic model developed for drug delivery by contact lenses•Transport barriers used to increase drug release durations from contacts
In this study, we describe a novel peripheral-nerve interface which makes use of highly flexible multi-electrode arrays that are integrated into hydrogel-based scaffolds to form a hybrid ...tissue-engineered electronic construct. This tissue-engineered electronic nerve interface (TEENI) is designed to be scalable to high channel counts using multiple polyimide-based "threads" that are evenly distributed through a volume of the nerve equal to its diameter times the distance between one or more nodes of Ranvier. Such scalability could greatly increase the precision and resolution of motor-control and sensory-feedback signals exchanged between amputees and advanced upper-limb prosthetic devices.
Therapeutic contact lenses: a patent review Dixon, Phillip; Shafor, Chancellor; Gause, Samuel ...
Expert opinion on therapeutic patents,
10/2015, Volume:
25, Issue:
10
Journal Article
Peer reviewed
Ophthalmic drugs are almost exclusively delivered via eye drops in spite of several deficiencies, including low bioavailability and poor compliance. Contact lenses have the potential to increase ...bioavailability by an order of magnitude, while also improving compliance.
In this review, the authors summarize advances in therapeutic contact lenses. The major focus of the review is on patents on drug-eluting contact lenses, but non-drug-eluting contacts that offer a therapeutic benefit are also included. The content is divided based on the broad technology of the patent, including novel materials, molecular imprinting, diffusion barriers, colloid encapsulation, surface modification, layering, and other novel approaches. In addition to patents, research publications are also included to facilitate the understanding of the mechanisms and challenges.
Among all non-invasive alternatives, contact lenses offer the highest bioavailability to the cornea due to the location of the lens in the immediate vicinity of the cornea. Several approaches have been patented to improve contact lens design for an extended release duration of drugs. Many technologies have successfully integrated suitable drug release profiles into contact lenses, but drug-eluting contacts are not yet commercialized likely due to regulatory challenges, including the high costs of clinical trials.
Regenerative peripheral-nerve interfaces are a novel method for integrating with the peripheral nervous system. These devices have the potential to isolate and transduce both afferent (sensory) and ...efferent (motor) neural signals to produce fine control of advanced prosthetics. We have developed a novel regenerative device comprised of microfabricated polyimide electrode threads supported by a hydrogel scaffold containing methacrylated hyaluronic acid, collagen I, and laminin to enable intimate contact with regenerating axons. While this advanced device holds theoretical promise for establishing a stable chronic neural interface, it also requires a novel surgical approach in comparison to current existing methods of peripheral neural interface technologies. Here we describe the development of the surgical methodology required for successful chronic implantation of the TEENI device in the rat sciatic nerve.
Neural-interface devices have the potential to isolate and transduce both afferent (sensory) and efferent (motor) neural signals of the peripheral nerve to and from electrical signals in ...instrumentation for stimulation and recording to produce fine control of advanced prosthetics. In order to potentiate the full spectrum of possible applications, the persistent foreign-body response needs to be addressed. Here we describe the cellular and extracellular components of chronically implanted polyimide threads suspended within a tricomponent hydrogel. The results of these experiments will contribute to design modifications for future fabrications of tissue-engineered-electronic-nerve-interface (TEENI) devices.
PDF