Treatment of low back pain through the systemic administration of medication is an essential approach in pain management, in particular for the pain that is usually associated with a variety of pathological conditions. Transdermal delivery of medication to local on-sites is considered superior to oral administration because of reduced side effects such as peptic ulcer and gastrointestinal bleeding and avoided liver first-pass metabolism.&nbsp;Microneedles are usually in hundreds of micron length range creates microchannels by penetrating through the skin's natural defense barrier—stratum corneum (SC) with relatively little or no pain and allows a direct permeation of drugs into the body with enhanced delivery efficiency for a wide scope of drug size and categories, such as peptide, protein, antibodies, and nanomaterials.&nbsp;To ensure the skin permeability and achieve the accurate release of drugs that is of critical importance in defining the personalized treatment protocol, microneedles with a range of shapes and materials have been designed. Meanwhile, several physical methods have been developed in conjunction with microneedles to control the diffusion of drugs in the body for disease specific applications of relevance to pain, for example, ultrasound,&nbsp;iontophoresis,&nbsp;electroporation,&nbsp;chemical enhancers.Alternatively, heat that can be taken easily and inexpensively from the form of hot clothes, hot baths, and heating pads/wraps could be used to accelerate the diffusion of drug molecules as the increase of temperature could promote the movement of molecules,&nbsp;thus helping control delivery of drugs. In practical applications, it emerges as an attractive approach in transdermal delivery of medication to integrate the heat therapy with microneedle patches to create a single simple smart sensor-assisted microneedle patch system that could control and monitor the release of drugs in an efficient manner. Recent development of technologies in 3D printing of functional structures and electronic devices could provide an opportunity to manufacture this smart system.In this paper, we presented a drug-encapsulated microneedle patch system integrated with a 3D-printed microheater device and demonstrate that the control of drug delivery rate can be well controlled by regulating the temperature with the microheater. 3D printing ability of microheater on various material and geometric types of substrates are firstly demonstrated. Theoretical model of the 3D printed droplet spreading on flat or curved substrates are evaluated to guide further design of the microheater. Then the printing ink solution consisting of MWCNTs and polydimethylsiloxane (PDMS) is developed with the concentration of MWCNTs up to 45% (10 times higher than ever). This super high concentration of MWCNT usually leads to the aggregation of MWCNTs in ink solution before printing and cracking of cured microheater after printing. This issue is solved by increasing the concentration of hexane in ink solution and an annealing process during the curing of printed microheater. The adhesion between the surface of carboxymethyl cellulose and microneedles is also evaluated as the heating function operates, and a facile strategy is proposed to enhance their integration adhesion by tuning the ratio of PDMS precursor, curing agent, and hexane. In vitro tests on rat's skin are conducted to assess the functional abilities of the microheater integrated microneedle patch system in drug delivery. Clear difference between microheater assisted microneedle dissolving and natural dissolving microneedle dissolving can be observed on tested rat skin. These studies provide a new route to design and manufacturing of sensor controlled medical devices and also establish the foundations for improving pain management via microneedle patches by seamlessly integrating wearable electronics to meet requirements for clinical use.&nbsp;&nbsp;

3d Printed Microheater Sensor-Integrated, Drug-Encapsulated Microneedle Patch System for Pain Management

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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