Wireless programmable electrochemical drug delivery micropump with fully integrated electrochemical dosing sensors

Implantable magnetically-actuated capsule for on-demand delivery

Many implantable drug delivery systems (IDDS) have been developed for long-term, pulsatile drug release. However, they are often limited by bulky size, complex electronic components, unpredictable drug delivery, as well as the need for battery replacement and consequent replacement surgery. Here, we develop an implantable magnetically-actuated capsule (IMAC) and its portable magnetic actuator (MA) for on-demand and robust drug delivery in a tether-free and battery-free manner. IMAC utilizes the bistable mechanism of two magnetic balls inside IMAC to trigger drug delivery under a strong magnetic field (|Ba| > 90 mT), ensuring precise and reproducible drug delivery (9.9 ± 0.17 μg per actuation, maximum actuation number: 180) and excellent anti-magnetic capability (critical trigger field intensity: ∼90 mT). IMAC as a tetherless robot can navigate to and anchor at the lesion sites driven by a gradient magnetic field (∇ Bg = 3 T/m, |Bg| < 60 mT), and on-demand release drug actuated by a uniform magnetic field (|Ba| = ∼100 mT) within the gastrointestinal tract. During a 15-day insulin administration in vivo, the diabetic rats treated with IMAC exhibited highly similar pharmacokinetic and pharmacodynamic profiles to those administrated via subcutaneous injection, demonstrating its robust and on-demand drug release performance. Moreover, IMAC is biocompatible, batter-free, refillable, miniature (only Φ 6.3 × 12.3 mm3), and lightweight (just 0.8 g), making it an ideal alternative for precise implantable drug delivery and friendly patient-centered drug administration.

A wearable, minimally-invasive, fully electrochemically-controlled feedback minisystem for diabetes management

Diabetes is a chronic disease affecting 10% of the population globally, and can lead to serious damage in the heart, kidneys, eyes, blood vessels or nerves. Commercial artificial closed-loop feedback systems can significantly improve diabetes management and save lives. However, they are large and expensive for users. Here, we demonstrate for the first time a wearable, minimally-invasive, fully electrochemically-controlled feedback minisystem for diabetes management. Both the working principles of the sensor and pump in the feedback system are based on electrochemical reactions. The smart minisystem was constructed based on integrating the thermoplastic polyurethane hollow microneedles with an electrochemical biosensing device on its outer layer and an electrochemical micropump facing the inner layer of the microneedles. The sensing device was constructed based on sputtering thin metal films through a shadow mask and electroplating Prussian blue on the surface of the microneedles, followed by the immobilization of glucose oxidase on the working electrode. The electrochemical micropump was constructed by sputtering the interdigital electrodes, followed by sealing with a thin elastic film, which was further integrated with the inner channels of the microneedles. Both the sensor and the pump were electrically powered. Via being controlled by a printed circuit board, the biosensing device monitored the levels of interstitial glucose continuously to drive the electrochemical pump to deliver insulin intelligently, in order to control blood glucose within the normal range. The closed-loop feedback system was studied for its capability in maintaining the blood glucose levels of diabetic rats under various physiological conditions. The utility of the intelligent feedback system was successfully demonstrated on diabetic rats for controlling the blood glucose levels within the normal range. The minisystem is wearable, small, cost-effective, precise, stable and painless. It is anticipated that this approach opens a new paradigm for the development of closed-loop diabetes minisystems and may lead to a compelling future for diabetes management.

Neural probe system for behavioral neuropharmacology by bi-directional wireless drug delivery and electrophysiology in socially interacting mice

Assessing the neurological and behavioral effects of drugs is important in developing pharmacological treatments, as well as understanding the mechanisms associated with neurological disorders. Herein, we present a miniaturized, wireless neural probe system with the capability of delivering drugs for the real-time investigation of the effects of the drugs on both behavioral and neural activities in socially interacting mice. We demonstrate wireless drug delivery and simultaneous monitoring of the resulting neural, behavioral changes, as well as the dose-dependent and repeatable responses to drugs. Furthermore, in pairs of mice, we use a food competition assay in which social interaction was modulated by the delivery of the drug, and the resulting changes in their neural activities are analyzed. During modulated food competition by drug injection, we observe changes in neural activity in mPFC region of a participating mouse over time. Our system may provide new opportunities for the development of studying the effects of drugs on behaviour and neural activity.

Technologies for monitoring electrophysiological effects of drugs in behaving animals have limitations. Here the authors report a wireless neural probe system with drug delivery capability for real-time monitoring of drug effects.

Microelectromechanical Systems (MEMS) for Biomedical Applications

The significant advancements within the electronics miniaturization field have shifted the scientific interest towards a new class of precision devices, namely microelectromechanical systems (MEMS). Specifically, MEMS refers to microscaled precision devices generally produced through micromachining techniques that combine mechanical and electrical components for fulfilling tasks normally carried out by macroscopic systems. Although their presence is found throughout all the aspects of daily life, recent years have witnessed countless research works involving the application of MEMS within the biomedical field, especially in drug synthesis and delivery, microsurgery, microtherapy, diagnostics and prevention, artificial organs, genome synthesis and sequencing, and cell manipulation and characterization. Their tremendous potential resides in the advantages offered by their reduced size, including ease of integration, lightweight, low power consumption, high resonance frequency, the possibility of integration with electrical or electronic circuits, reduced fabrication costs due to high mass production, and high accuracy, sensitivity, and throughput. In this context, this paper aims to provide an overview of MEMS technology by describing the main materials and fabrication techniques for manufacturing purposes and their most common biomedical applications, which have evolved in the past years.

A Wirelessly Controlled Scalable 3D-Printed Microsystem for Drug Delivery

Here we present a 3D-printed, wirelessly controlled microsystem for drug delivery, comprising a refillable microreservoir and a phase-change peristaltic micropump. The micropump structure was inkjet-printed on the back of a printed circuit board around a catheter microtubing. The enclosure of the microsystem was fabricated using stereolithography 3D printing, with an embedded microreservoir structure and integrated micropump. In one configuration, the microsystem was optimized for murine inner ear drug delivery with an overall size of 19 × 13 × 3 mm3. Benchtop results confirmed the performance of the device for reliable drug delivery. The suitability of the device for long-term subcutaneous implantation was confirmed with favorable results of implantation of a microsystem in a mouse for six months. The drug delivery was evaluated in vivo by implanting four different microsystems in four mice, while the outlet microtubing was implanted into the round window membrane niche for infusion of a known ototoxic compound (sodium salicylate) at 50 nL/min for 20 min. Real-time shifts in distortion product otoacoustic emission thresholds and amplitudes were measured during the infusion, demonstrating similar results with syringe pump infusion. Although demonstrated for one application, this low-cost design and fabrication methodology is scalable for use in larger animals and humans for different clinical applications/delivery sites.

A 3D-Printed Modular Microreservoir for Drug Delivery

Reservoir-based drug delivery microsystems have enabled novel and effective drug delivery concepts in recent decades. These systems typically comprise integrated storing and pumping components. Here we present a stand-alone, modular, thin, scalable, and refillable microreservoir platform as a storing component of these microsystems for implantable and transdermal drug delivery. Three microreservoir capacities (1, 10, and 100 µL) were fabricated with 3 mm overall thickness using stereolithography 3D-printing technology, enabling the fabrication of the device structure comprising a storing area and a refill port. A thin, preformed dome-shaped storing membrane was created by the deposition of parylene-C over a polyethylene glycol sacrificial layer, creating a force-free membrane that causes zero forward flow and insignificant backward flow (2% of total volume) due to membrane force. A septum pre-compression concept was introduced that enabled the realization of a 1-mm-thick septa capable of ~65000 leak-free refill punctures under 100 kPa backpressure. The force-free storing membrane enables using normally-open micropumps for drug delivery, and potentially improves the efficiency and precision of normally-closed micropumps. The ultra-thin septum reduces the thickness of refillable drug delivery devices, and is capable of thousands of leak-free refills. This modular and scalable device can be used for drug delivery in different laboratory animals and humans, as a sampling device, and for lab-on-a-chip and point-of-care diagnostics applications.

Flexible fiber-based optoelectronics for neural interfaces

Neurological and psychiatric conditions pose an increasing socioeconomic burden on our aging society. Our ability to understand and treat these conditions relies on the development of reliable tools to study the dynamics of the underlying neural circuits. Despite significant progress in approaches and devices to sense and modulate neural activity, further refinement is required on the spatiotemporal resolution, cell-type selectivity, and long-term stability of neural interfaces. Guided by the principles of neural transduction and by the materials properties of the neural tissue, recent advances in neural interrogation approaches rely on flexible and multifunctional devices. Among these approaches, multimaterial fibers have emerged as integrated tools for sensing and delivering of multiple signals to and from the neural tissue. Fiber-based neural probes are produced by thermal drawing process, which is the manufacturing approach used in optical fiber fabrication. This technology allows straightforward incorporation of multiple functional components into microstructured fibers at the level of their macroscale models, preforms, with a wide range of geometries. Here we will introduce the multimaterial fiber technology, its applications in engineering fields, and its adoption for the design of multifunctional and flexible neural interfaces. We will discuss examples of fiber-based neural probes tailored to the electrophysiological recording, optical neuromodulation, and delivery of drugs and genes into the rodent brain and spinal cord, as well as their emerging use for studies of nerve growth and repair.

Passive, wireless transduction of electrochemical impedance across thin-film microfabricated coils using reflected impedance

A new method of wirelessly transducing electrochemical impedance without integrated circuits or discrete electrical components was developed and characterized. The resonant frequency and impedance magnitude at resonance of a planar inductive coil is affected by the load on a secondary coil terminating in sensing electrodes exposed to solution (reflected impedance), allowing the transduction of the high-frequency electrochemical impedance between the two electrodes. Biocompatible, flexible secondary coils with sensing electrodes made from gold and Parylene C were microfabricated and the reflected impedance in response to phosphate-buffered saline solutions of varying concentrations was characterized. Both the resonant frequency and impedance at resonance were highly sensitive to changes in solution conductivity at the secondary electrodes, and the effects of vertical separation, lateral misalignment, and temperature changes were also characterized. Two applications of reflected impedance in biomedical sensors for hydrocephalus shunts and glucose sensing are discussed.

Minimally invasive probes for programmed microfluidic delivery of molecules in vivo

Site-specific drug delivery carries many advantages of systemic administration, but is rarely used in the clinic. One limiting factor is the relative invasiveness of the technology to locally deliver compounds. Recent advances in materials science and electrical engineering allow for the development of ultraminiaturized microfluidic channels based on soft materials to create flexible probes capable of deep tissue targeting. A diverse set of mechanics, including micro-pumps and functional materials, used to deliver the drugs can be paired with wireless electronics for self-contained and programmable operation. These first iterations of minimally invasive fluid delivery devices foreshadow important advances needed for clinical translation.

An ultrasonically powered implantable device for targeted drug delivery

A wirelessly powered implantable device is proposed for fully programmable and localized drug delivery. The implant is powered using an external ultrasonic transmitter and operates at <; 5% of the FDA diagnostic ultrasound intensity limit. Drug release is achieved through electrical stimulation of drug-loaded polypyrrole nanoparticles. A design methodology for the implant electronics is presented and experimentally demonstrated to be accurate in predicting the concentration of the released drug. To the best of our knowledge, this is the first ultrasonically powered implantable device platform for targeted drug delivery using electroresponsive polymers. The active area of the implant electronics is just 3 mm × 5 mm.

Microfluidic neural probes: in vivo tools for advancing neuroscience

Microfluidic neural probes hold immense potential as in vivo tools for dissecting neural circuit function in complex nervous systems. Miniaturization, integration, and automation of drug delivery tools open up new opportunities for minimally invasive implants. These developments provide unprecedented spatiotemporal resolution in fluid delivery as well as multifunctional interrogation of neural activity using combined electrical and optical modalities. Capitalizing on these unique features, microfluidic technology will greatly advance in vivo pharmacology, electrophysiology, optogenetics, and optopharmacology. In this review, we discuss recent advances in microfluidic neural probe systems. In particular, we will highlight the materials and manufacturing processes of microfluidic probes, device configurations, peripheral devices for fluid handling and packaging, and wireless technologies that can be integrated for the control of these microfluidic probe systems. This article summarizes various microfluidic implants and discusses grand challenges and future directions for further developments.

Application of Microfluidic Technique in Drug Delivery

Drug delivery as a strategy to improve the effect of therapeutic treatment is gaining tremendous interest in biomedical research. The recent advancement in microfluidic technique designed to precisely control the liquid at micro or nano liter level has shed some new lights on reshaping the ongoing drug delivery research. In this aspect, this present mini-review gives an overview on the potential applications of microfluidic technique in the area of drug delivery, which basically covers the fabrication of drug delivery carriers and the design of microfluidic-based smart systems for localized in vivo drug delivery.