A PZT insulin pump integrated with a silicon microneedle array for transdermal drug delivery

Abstract

Many of the compounds in drugs cannot be effectively delivered using current drug delivery techniques (e.g., pills and injections). Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of the skin. As the primary barrier to transport is located in the upper tissue, MicroElectro-Mechanical-System (MEMS) technology provides novel means, such as microneedle array and PZT pump, in order to increase permeability of human skin with efficiency, safety and painless delivery, and to decrease the size of the pump. Microneedle array has many advantages, including minimal trauma at penetration site because of the small size of the needle, free from condition limitations, painless drug delivery, and precise control of penetration depth. These will promote the development of biomedical sciences and technology and make medical devices more humanized. So far, most of the insulin pumps being used are mechanical pumps. We present the first development of this novel technology, which can assemble the PZT pump and the microneedle array together for diabetes mellitus. The microneedle array based on a flexible substrate can be mounted on non-planar surface or even on flexible objects such as a human fingers and arms. The PZT pump can pump the much more precision drug accurately than mechanical pump and the overall size is much smaller than those mechanical pumps. The hollow wall straight microneedle array is fabricated on a flexible silicon substrate by inductively coupled plasma (ICP) and anisotropic wet etching techniques. The fabricated hollow microneedles are 200 lm in length and 30 lm in diameter. The microneedle array, which is built with onboard fluid pumps, has potential applications in the chemical and biomedical fields for localized chemical analysis, programmable drug-delivery systems, and very small, precise fluids sampling. The microneedle array has been installed in an insulin pump for demonstration and a leak free packaging is introduced.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…Worth noting here is that a thorough theoretical analysis of acoustic evanescent waves that scatter into a fluid environment in a manner similar to what is used in FPW pumps was presented by Williams and Hill (1987) several years prior to the experimental work. The possible applications for acoustic pumping technology extend into medical applications, for example, the insulin pump reported by Ma et al (2006), where the PZT was used in a Helmholtz cavity arrangement to deliver insulin into a silicon patch with surface machined hollow microneedles designed to painlessly puncture the skin. By applying this idea at far lower frequencies, well into the audible range at around 100 Hz, but in a set of resonance cavities external to the microfluidics device, each holding fluids to be delivered, Langelier et al (2009) were able to selectively pump these fluids through the device as shown in Fig.…”

Feasibility Study of Carbon Nanotube Microneedles for Rapid Transdermal Drug Delivery

“…Fabrication of both silicon and CNT-SU8 microneedles offer similar advantages in terms of geometry customization and parallel processing of large numbers of microneedles. In characterizing the fabrication process for silicon microneedles, reactive ion etching (RIE) is presumed to be the primary method for defining the microneedle shape with additional processes such as wet etching or micromachining used as secondary methods to optimize the microneedle geometry[1, [5][6][7]. For each process used in the fabrication method, a difficulty factor between 1 through 3 is assigned based on the difficulty of the process on the laboratory scale (Table I).…”

Ordered Mesoporous Thin Film Ferroelectrics of Biaxially Textured Lead Zirconate Titanate (PZT) by Chemical Solution Deposition

“…[3][4][5][6][7] For example, applications of high performance piezoelectric MEMS include transducers, actuators, micro-pumps, and inkjet printheads, to mention only a few. [8][9][10][11][12] PZT materials, in particular, have been shown to outperform many other piezoelectrics, which is due in part to the large room-temperature electromechanical coupling factors. 13,14 The maximum values of the latter coupling factors, the piezoelectric coefficients, and the dielectric permittivity occur in the immediate vicinity of the so-called morphotropic phase boundary (Zr/Ti = 52/48).…”