Hollow Microneedle Technology

Hollow microneedles are micron-sized microinjectors in which a hollow needle tip is pierced into the skin and the drug is driven into the body by a pressure-driven tissue fluid concentration gradient, allowing for drug delivery. Hollow microneedles can be divided into a single hollow microneedle and an array of multiple microneedles. Single hollow microneedles are painless, making them more acceptable to patients. Microneedle arrays can cover a larger area of skin during a single administration, and these microneedles generally have a faster onset of action, larger area of play, and higher bioavailability. CD Formulation can provide customers with hollow microneedle preparations, including silicon hollow microneedles, metal hollow microneedles, and polymer hollow microneedles.

Fig. 1 Picture of hollow microneedles. (Cheng et al., 2023)

About Hollow Microneedles

Hollow microneedles can handle large doses of drug solutions compared to solid microneedles. Hollow microneedles are also capable of delivering drugs into the epidermis or dermis where high molecular weight compounds are appropriate. In addition, it allows for controlled drug release over time, making it suitable for use with liquid vaccine formulations. The hollow microneedle is an active drug delivery system that forms an internal non-pressurized drug reservoir based on which the drug can be diffused into the dermis. Tunable release kinetics can be achieved by varying the material formulation and manufacturing parameters of hollow microneedles. Hollow microneedles are similar to hypodermic needles in that the flow rate and pressure can be designed and adjusted. By varying process parameters such as the aspect ratio of the microneedle, different delivery rates can be achieved, such as rapid release, slow delivery, or time-dependent.

Preparation Services for Hollow Microneedles

Based on the microneedle preparation technology and development process that CD Formulation has, we can provide our customers with the following types of microneedle product preparation services.

1. Silicon hollow microneedle preparation

Silicon has a crystalline structure and is a commonly used material for microneedle preparation. Micromachining technology for the preparation of silicon hollow microneedles is available on a large scale.

2. Metal hollow microneedle preparation

Metal is another commonly used material for the preparation of microneedles. The cost of metal is lower than that of silicon, and the mechanical properties are better, which is more conducive to puncturing the stratum corneum when delivering drugs, and the preparation techniques include molding, sputtering, electroplating, laser etching and photochemical etching, and other microelectronic processes.

3. Preparation of polymeric hollow microneedles

Polymers are the development direction for the preparation of new microneedles because of their good biocompatibility and flexibility. The preparation techniques for hollow microneedles are mainly micro-molding and hot pressing.

Preparation Technologies

The current microfabrication technologies used to manufacture hollow microneedles include photolithography, dry/wet etching, 3D printing, etc.

Advantages of Hollow Microneedles

Hollow microneedles have the following characteristics:

a. Low cost, simple preparation, and easy mass production;
b. High retention of the hollow structure and geometry of traditional hypodermic needles, with high drug loading capacity and good puncture performance;
c. Minimally invasive, painless, high biosafety and high patient compliance.

CD Formulation can visualize the geometry of microneedles by scanning electron microscopy (SEM). If you are interested in our technology, please feel free to contact us.