1 3 Microsyst Technol DOI 10.1007/s00542-017-3332-x TECHNICAL PAPER Fabrication and performance characterization of miniature axial fans Hamed Keramati 1 · Weng-Kong Chan 1 · Jianmin Miao 1 Received: 2 February 2017 / Accepted: 5 February 2017 © Springer-Verlag Berlin Heidelberg 2017 one of the limitations that impede the development of smaller devices is the problem caused by the rate of heat removal. Miniaturized fans could solve some of these prob- lems and reduce the effect of limitations related to heat dissipation. Miniaturized fans are used in micro channels, micro air vehicles (MAV) and chip-scale cooling systems for elec- tronic devices. They can also be found in micro combustion motors as a necessary part of the chemical mixing systems at micro-scale. Axial fans have some special advantages that make them particularly attractive in many applications. Its compactness and light weight are two key characteris- tics. Moreover, as an air mover, the ability of generating sufficient pressure at a relatively large flow rate is a critical factor. The distinct advantage that rotary fan has over con- ventional diaphragm pumping system is that it produces a constant flow rate. Numerous researches have been carried out on the fabrication of miniaturized turbomachines. However, in general, these researches are focused on centrifugal turbomachines because it is very difficult to make axial 3-D structures using micro fabrication techniques such as planar lithography which is the most common method in micro fabrication (Epstein 2003). Other than this, grey scale lithography is a method where different dosage of exposure is used in a single step using a grey scale pat- tern, instead of a monochromatic pattern, on a mask. This method can be used to fabricate a three dimensional structure like micro capillaries with surface roughness of 0.98 μm (Mori et al. 2005). An inkjet printer was used to print grey-tone masks (GTM) by changing the density of printed dots. GMT techniques can also be achieved using X-ray lithography (Mouroulis et al. 2003). A grey scale maskless lithography method was proposed by Rammo- han et al. (2011) for the fabrication of three dimensional Abstract This paper presents the fabrication and per- formance characterization of miniature axial fans that are developed using 2D blade profiles. 12 prototypes, with an outer diameter of 5 mm, having different blade angles and blade profiles were fabricated using UV photolithog- raphy with SU-8 as photoresist. Tests were conducted at 3 different speeds to examine the applicability of similarity laws. The results show that cambered profiles generated much higher pressure and flow rate as compared to a flat plate profile. For flat plate profiles, a maximum pressure of 0.55 Pa and a flow rate of 9.9 cm 3 /s are generated with a blade angle of 42° when the fan is operating at 20,000 rpm. This is much lower than that obtained by cambered profiles where a maximum pressure of 1.15 Pa and a flow rate of 14.6 cm 3 /s are generated with a blade angle of 60°. The effects of increasing blade number and blade angle have a positive effect on the flow rate delivered and pressure gen- erated but the effects of increasing blade number is more effective in enhancing fan performance. The results also show that dynamic similarity is observed for rotational speeds of 15,000 and 20,000 rpm. 1 Introduction As technology advances rapidly, there is a growing demand for miniaturized size fans in many applications. Air flow controlling devices in micro scale experimental set-ups is a field where small fans are essential. In electronic devices, * Weng-Kong Chan mwkchan@ntu.edu.sg 1 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore