3D Printing Technology for Microneedles Preparation

Microneedles need to have good mechanical properties and biocompatibility in order to meet the safety requirements of their applications, so the selection of materials, structural design and the corresponding preparation technology of microneedles are directly related to their effectiveness. In general, the smoother the surface of the microneedle, the better the microneedle can play a safe, painless and quantitative release advantage. 3D printing technology can process and take into account the characteristics of fast, high precision and large format, which can meet the above-mentioned microneedle size requirements, and the surface of the processed microneedle is smooth, which provides technical support for minimally invasive and painless microneedle treatment effect, and also provides a feasible solution for fast and efficient industrialized production. It also provides a feasible solution for fast and efficient industrial production.

About 3D Printing Technology

3D printing is a new technology for the preparation of microneedles, which can be designed and printed quickly through computer-aided design (CAD) with customizable needle density, length and shape. Commonly used 3D printing technologies include selective laser sintering (SLS), stereolithography (SLA) and fused deposition modeling (FDM); SLS and SLA printers are capable of producing microneedles smaller than 100 μm; FDM is versatile and cost-effective and can be printed using biocompatible materials such as polylactic acid (PLA) and PVA.

How to Prepare Microneedles

Customized devices

3D printing allows for custom devices and the design can be adapted to fit specific patient needs. Microneedle patches can also be manufactured on-demand, eliminating the need for storage space in clinics and laboratories.

3D Printed microneedle patches

Microneedle patches designed using standard CAD software consist of a hollow microneedle rod body with its aperture, internal microchannels, microstores, and an outlet for fluid supply. Microneedles can be 3D printed using stereolithography and biocompatible polymers.

Quality evaluation

• Physical properties

Typically, the geometry of microneedles can be evaluated by visual inspection, body microscopy, and scanning electron microscopy (SEM) to characterize the size, surface morphology, and distribution of microneedles on the array.

• Mechanical strength analysis

Microneedles should have good mechanical strength and toughness to insert into the skin and deliver drugs to subcutaneous tissues, and resist fracture and bending damage. The mechanical strength of microneedles is related to the matrix material used to prepare the microneedles, the water content of the microneedles, and the geometry of the microneedles. Usually, mechanical strength experiments are combined with insertion studies and evaluated based on parameters such as insertion force, insertion depth, and success rate of microneedle penetration.

• Stability analysis

The stability study of microneedles examines the effect of different temperatures and humidity on microneedle patches. The microneedle patch is placed in different temperature and humidity environments to investigate the physical and chemical stability of the microneedle patch, such as microneedle mechanical strength, drug stability, etc.

Advantages of 3D Printing Technology

• 3D printing does not require molds, allowing for free-form molding.
• Reduces assembly steps and the use of auxiliary tools for manufacturers.
• Reduces medical device product development and manufacturing costs.
• Accelerate product innovation and design iterations.

Medical applications of 3D printing technology include endoscopes, cardiovascular stents and glaucoma infusion staples, and drug delivery microneedles, as well as being used in medical devices such as spiral syringe needles for minimally invasive surgery, valves for gene sequencers, and microfluidic chips.