Microelectromechanical systems drug delivery

MICROELECTROMECHANICAL SYSTEMS DRUG DELIVERY DEVICES Description of Drug Delivery System... 

Yuzhakov et al. [93] describe the production of an intracutaneous microneedle array and provide an account of its use (microfabrication technology). Various embodiments of this invention can include a microneedle array as part of a closed loop system smart patch to control drug delivery based on feedback information from analysis of body fluids. Dual purpose hollow microneedle systems for transdermal delivery and extraction which can be coupled with electrotransport methods are also described by Trautman et al. [91] and Allen et al. [100]. These mechanical microdevices which interface with electronics in order to achieve a programmed or controlled drug release are referred to as microelectromechanical systems (MEMS) devices. 

Microelectromechanical systems (MEMS) devices can potentially administer complex dosing patterns using very small amounts of drugs. This system could be used to deliver protein molecules intraocularly such as neuroprotectors or anti-angiogenic molecules. Delivery of chemotherapeutic agents using the MEMS may also be a future possibility. 

Figure 13 Diagrams of a prototype of a MEMS drug delivery device incorporating multiple sealed compartments that can be opened on demand to deliver a drug dose. (A) Prime grade silicon wafers are sandwiched between two layers of silicon nitride and each device contained reservoirs that extended completely through the wafer. The devices also contain a cathode and an anode between which small electric potentials can be passed. (B) Each reservoir is square pyramidal in shape with one large and one small square opening. The reservoirs have a volume of approximately 25 nL and are sealed on the small square end with the anode which is a 0.3- im thick gold membrane. Abbreviation MEMS, microelectromechanical systems.

Figure 14 Scanning electromicrograph of a single reservoir in a prototypical MEMS drug delivery device. (A) The gold anode is in place over the small square end of the reservoir. (B) After passage of a small electrical potential the gold anode has dissolved. Abbreviation MEMS, microelectromechanical systems.

Microneedles are a type of micromachined structure that promotes the transport of substance through an interface or media, via enhanced permeability or microchannels. In most cases, microneedles are similar in shape to hypodermic needle but are much smaller in size, enabling localized and painless delivery of drugs into cells or tissues. Microneedles, which can be either singular or grouped in arrays, are prepared using microelectromechanical systems (MEMS)... 

In summary, desired characteristics of a drug delivery system would include (1) controlled and on-demand dosing, (2) biocompatibility, (3) minimum drug degradation within the device over the period of implantation, and (4) localized drug delivery to minimize systemic toxicides. Microelectromechanical system (MEMS) technology has been proposed as a platform for controlled drug delivery. 

Cao L, Mantell S, Polla D (2001) Design and simulation of an implantable medical drug delivery system using microelectromechanical systems technology. Sens Actuators a-Phys 94 117-125... 

The main aim of this review is to highlight the various smart polymeric materials and the drug delivery systems (DDS) that exploit them. These are useful to realize biomimetic devices [18], intelligent medical instruments and auxiliaries [19, 20], electrochemical devices [21], artificial muscles [22], heat shrinkable materials for electronics packaging [23], microelectromechanical systems [24] and actuators and sensors [25],... 

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