An optimized hollow microneedle for minimally invasive blood extraction

• Published in: Biomedical microdevices Vol. 15; no. 1; pp. 17 - 25
• Main Authors: Li, Cheng Guo, Lee, Chang Yeol, Lee, Kwang, Jung, Hyungil
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2013; Springer Nature B.V
• Subjects: Animals; Biochemistry; Biological and Medical Physics; Biomedical Engineering and Bioengineering; Biophysics; Blood Specimen Collection - adverse effects; Blood Specimen Collection - instrumentation; Blood tests; Engineering; Engineering Fluid Dynamics; Humans; Hypodermic needles; Male; Mechanical Phenomena; Medical device industry; Mice; Microtechnology - instrumentation; Nanotechnology; Needles; Blood extraction; Minimal invasion; Hollow microneedles; Bevel angle
• ISSN: 1387-2176; 1572-8781
• DOI: 10.1007/s10544-012-9683-2

The healthcare system relies widely on biochemical information obtained from blood sample extracted via hypodermic needles, despite the invasiveness and pain associated with this procedure. Therefore, an alternative micro-scale needle for minimally invasive blood sampling is highly desirable. Traditional fabrication techniques to create microneedles do not generate needles with the combined features of a sharp tip, long length, and hollow structure concurrently. Here, we report the fabrication of a microneedle long enough to reach blood vessels and sharp enough to minimize nerve contact for minimally invasive blood extraction. The microneedle structure was precisely controlled using a drawing lithography technique, and a sharp tip angle was introduced using a laser-cutting system. We investigated the characteristics of a microneedle with a length of 1,800 μm length, an inner diameter of 60 μm, a tip diameter of 120 μm, and a 15° bevel angle through in-vitro liquid extraction and mechanical strength analysis. We demonstrated that the proposed structure results in blood extraction at a reasonable rate, and that a microneedle with this geometry can reliably penetrate skin without breaking. We integrated this microneedle into a blood extraction device to extract a 20 μl volume of mouse blood in-vivo . Our optimized, hollow microneedle can potentially be incorporated with other cutting-edge technologies such as microactuators, biosensors, and microfluidic chips to create blood analysis systems for point-of-care diagnostics.