Microneedle technologies for (trans)dermal drug and vaccine delivery.

Micropumping has emerged as a critical research area for many electronics and biological applications. A significant driving force underlying this research has been the integration of pumping mechanisms in micro total analysis systems and other multi-functional analysis techniques. Uses in electronics packaging and micromixing and microdosing systems have also capitalized on novel pumping concepts. The present work builds upon a number of existing reviews of micropumping strategies by focusing on the large body of micropump advances reported in the very recent literature. Critical selection criteria are included for pumps and valves to aid in determining the pumping mechanism that is most appropriate for a given application. Important limitations or incompatibilities are also addressed. Quantitative comparisons are provided in graphical and tabular forms.

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Recent advances in microscale pumping technologies: a review and evaluation

Enabling individualized therapy through nanotechnology.

Piezoelectric materials, a type of "smart" material that generates electricity while deforming and vice versa, have been used extensively for many important implantable medical devices such as sensors, transducers, and actuators. However, commonly utilized piezoelectric materials are either toxic or nondegradable. Thus, implanted devices employing these materials raise a significant concern in terms of safety issues and often require an invasive removal surgery, which can damage directly interfaced tissues/organs. Here, we present a strategy for materials processing, device assembly, and electronic integration to 1) create biodegradable and biocompatible piezoelectric PLLA [poly(l-lactic acid)] nanofibers with a highly controllable, efficient, and stable piezoelectric performance, and 2) demonstrate device applications of this nanomaterial, including a highly sensitive biodegradable pressure sensor for monitoring vital physiological pressures and a biodegradable ultrasonic transducer for blood-brain barrier opening that can be used to facilitate the delivery of drugs into the brain. These significant applications, which have not been achieved so far by conventional piezoelectric materials and bulk piezoelectric PLLA, demonstrate the PLLA nanofibers as a powerful material platform that offers a profound impact on various medical fields including drug delivery, tissue engineering, and implanted medical devices.

https://www.pnas.org/content/pnas/117/1/214.full.pdf

Biodegradable nanofiber-based piezoelectric transducer

The development of flexible piezoelectric nanogenerators has experienced rapid progress in the past decade and is serving as the technological foundation of future state-of-the-art personalized healthcare. Due to their highly efficient mechanical-to-electrical energy conversion, easy implementation, and self-powering nature, these devices permit a plethora of innovative healthcare applications in the space of active sensing, electrical stimulation therapy, as well as passive human biomechanical energy harvesting to third party power on-body devices. This article gives a comprehensive review of the piezoelectric nanogenerators for personalized healthcare. After a brief introduction to the fundamental physical science of the piezoelectric effect, material engineering strategies, device structural designs, and human-body centered energy harvesting, sensing, and therapeutics applications are also systematically discussed. In addition, the challenges and opportunities of utilizing piezoelectric nanogenerators for self-powered bioelectronics and personalized healthcare are outlined in detail.

Piezoelectric nanogenerators for personalized healthcare.

We present the design of a new controlled drug delivery system potential for in vitro injection of diabetics. The system incorporates some integrated circuit units and microelectromechanical system devices, such as micropump, microneedle array and microsensor. Its goal is to achieve safer and more effective drug delivery. Moreover, a valveless micropump excited by the piezoelectric actuator is designed for the drug delivery system, and a simple fabrication process is proposed. A dynamic model is developed for the valveless micropump based upon the mass conservation. To characterize the micropump, a complete electro-solid-fluid coupling model, including the diffuser/nozzle element and the piezoelectric actuator, is built using the ANSYS software. The simulation results show that the performance of micropump is in direct proportion to the stroke volume of the pump membrane and there is an optimal thickness of the piezoelectric membrane under the 500 V/mm electric field. Based on this simulation model, the effects of several important parameters such as excitation voltage, excitation frequency, pump membrane dimension, piezoelectric membrane dimension and mechanical properties on the characteristics of valveless micropump have been investigated.

Study on a piezoelectric micropump for the controlled drug delivery system

We designed a valveless micropump excited by a piezoelectric actuator for medical applications. The complete electric–fluid–solid coupling model is built upon using ANSYS software (Canonsburg, PA) to investigate the behaviors of the micropump. The effects of the geometrical dimensions on the micropump characteristics and its efficiency are analyzed. The simulation results show that there is an optimal thickness of the piezoelectric layer to obtain a large pump flow, and that this optimal thickness is affected by the material and the thickness of the pump membrane. To enhance the performance of the micropump, some important diffuser parameters, such as the diffuser length, the diffuser angle, and the neck width, should be optimized. However, the variations of the diffuser’s geometrical dimensions do not affect the optimal thickness of the piezoelectric layer.

Simulation and optimization of a piezoelectric micropump for medical applications

This article investigates mechanical behavior of a circular piezoelectric actuator for valveless micropumps. An analytical equation for analyzing the deflection of multi-layer piezoelectric structure is derived based on the electro-elastic theory and the thin plate theory. We assume that the distribution of electric potential along the thickness direction is governed by the square law to satisfy the Maxwell static electricity equation. The validity of the proposed analytical model is further studied by using the ANSYS software. Furthermore, the effects of the dimensions and material properties of a multi-layer piezoelectric structure on its deflection are analyzed for optimal design of the actuator. The simulation results show that the thickness ratio of the piezoelectric layer and the passive plate in the multi-layer structure can be optimized to obtain the largest deflection. The important design parameters of the piezoelectric actuator, such as the passive plate properties and material, and the piezoel...

Modeling and Numerical Analysis of a Circular Piezoelectric Actuator for Valveless Micropumps

A novel intelligent drug delivery system potential for the more effective therapy of the diabetics was proposed, and the composition of system was analyzed. Based on the design of micro-electro-mechanical systems (MEMS), an iterative modeling process was introduced. Unified modeling language (UML) was employed to describe the function requirement, and different diagrams were built up to explore the static model, the dynamic model and the employment model. The mapping analysis of different diagrams can simply verify the consistency and completeness of the system model.

Intelligent drug delivery system using UML diagrams analysis

Given complexity of the design and manufacturing processes of microelectromechanical system (MEMS) products, we present a unified modeling language (UML) based design approach for multi-domain products or systems like MEMS to designing and evaluating possible solutions at the early design stage to shorten their development time. Specifically, the proposed approach is used to model and analyze a novel drug delivery system combining MEMS devices and integrated circuit (IC) units. This drug delivery system aims to be used for safer and more effective therapy of the diabetics. Two design models about the whole drug delivery system and its micropump subsystem are established using UML diagrams; in particular a composition diagram with components and ports describes the topology of the system. Through design and simulation on the micropump subsystem, it is found that the variations of geometrical dimension and excitation voltage affect the characterization of the micropump. The simulation results demonstrate and validate the proposed approach, and can be used as a significant reference for the designer to design the optimal micropump.

Qifeng Cui

Papers

Study on a piezoelectric micropump for the controlled drug delivery system

Simulation and optimization of a piezoelectric micropump for medical applications

Modeling and Numerical Analysis of a Circular Piezoelectric Actuator for Valveless Micropumps

Intelligent drug delivery system using UML diagrams analysis

A UML-based object-oriented approach for design and simulation of a drug delivery system