Fabrication of microneedles for skin interstitial fluid extraction for allergy testing

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For transdermal drug delivery, skin fluid and blood extraction, the conventional stainless steel needle causes pain to the patients and is hard to be integrated with other medical devices at point-of-care-test fields. One solution to those limitations is micro-needle array because of its minimal invasive area/depth causing less pain, and ability to be integrated with other micro-devices. Moreover, no cases of infection by micro-needles have been reported so far. Such micro-needles can be solid or hollow with an approximate length of 500-1200 um and an external diameter of not more than 300 µm.The supporting company ExVivo Labs is pioneering novel point-of-care medical technologies for screening allergies. Allergies are a pervasive problem affecting approximately 60 million people in Canada and the United States. It is estimated that medical expenditures to treat allergic rhinitis in the U.S. almost doubled from $6.1 billion in 2000 (in 2005 dollars) to $11.2 billion in 2005, representing a significant and increasing economic burden to society. ExVivo Labs targets to reduce the number of emergency visits to the hospital, workplace absenteeism for millions of people, and overall cost of allergies. Its allergy test patches are based onextraction using micro-needle array of disease-indicating biomarkers, such as immunoglobulin-E (IgE), which mediates type I hypersensitivity reactions, known as allergies. In this CRD project, we aim to fabricate hollow silicon and polymer, out-of-plane and in-plane, micro-needle array using MEMS microfabrication techniques, notably photolithography and deep silicon etching. The fabricated needles will be subsequently sharpened to under 10 micrometers by isotropic dry and/or wet etching, for painless insertion into skin.