Sensors and Actuators B 138 (2009) 21–27 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb Integrated microfluidic components on a printed wiring board platform Keryn Lian a,∗ , Shawn O’Rourke b , Daniel Sadler c , Manes Eliacin c , Claudia Gamboa c , Robert Terbrueggen d , Marc Chason e a Department of Materials Science and Engineering, University of Toronto, Canada b Flexible Display Center, Arizona State University, AZ, USA c Motorola, Inc., IL, USA d DxTerity Diagnostics, CA, USA e Marc Chason and Associates, Inc., IL, USA article info Article history: Received 29 May 2008 Received in revised form 5 January 2009 Accepted 31 January 2009 Available online 24 February 2009 Keywords: Printed wiring board (PWB) Microfluidics MEMS Bio-chip Embedded heaters abstract Advancements in printed wiring board (PWB) materials and processes have enabled the PWB to become an ideal low cost/high volume fabrication vehicle for integrated Micro-Electro-Mechanical Systems (MEMS). It is especially applicable for single-use microfluidic devices with electrochemical detection sensors, since detection and signal processing can be integrated on a single low cost platform. To show- case the PWB as a platform for MEMS applications, a MEMS microfluidic system for DNA amplification and detection has been developed using PWB materials and processes. PWB, embedded passives (EP), and high-density interconnect (HDI) technologies have been utilized to fabricate these microfluidic structures following processes analogous to those for fabricating silicon MEMS. Several functional blocks, such as heating and sensing elements, together with electrical circuitries have been demonstrated. © 2009 Elsevier B.V. All rights reserved. 1. Introduction In recent years, integrated bio-chip and microfluidic systems have proven to be of increasing importance in clinical diagnostic and pharmaceutics, due to their fast response time from sample-to- answer, their tight integration requiring limited user intervention, and their potential for low-cost manufacturing. A key goal is to inte- grate the functional components or blocks, such as amplification, mixing, hybridization, and detection, into a single system to form a “lab-on-a-chip”. Among these functions, the amplification of assays is one of the most involved and, therefore, the perfection of the poly- merase chain reaction (PCR) process has attracted much attention. PCR is widely used as a molecular biological tool to replicate DNA via temperature cycling. The study of on-chip PCR has grown rapidly as summarized in several review articles [1–4]. Several material platforms [5], including silicon [6], glass [7], ceramics [8,9], and polymers [10,11] have been proposed to achieve such highly integrated and multifunctional “lab-on-a- chip” systems. These materials have their respective advantages and disadvantages in terms of overall performance, chemical and ∗ Corresponding author at: Department of Materials Science and Engineering, University of Toronto, 184 College St, Rm 140, Toronto, Ont., Canada M5S 3E4. Tel.: +1 416 978 8631; fax: +1 416 978 4155. E-mail address: keryn.lian@utoronto.ca (K. Lian). mechanical stability, and cost. The printed wiring board (PWB) has also become a promising alternative, especially for those devices that require transferring and processing of electrical sig- nals. For instance, Wego et al. have demonstrated sophisticated microfluidic systems containing micropumps, valves, and a pres- sure sensor using PWB materials and processes [12,13]. The Clinical Micro-Sensors (CMS) eSensor ® is a PWB based micro-array elec- trochemical DNA sensors produced with processing techniques common in the electronics industry [14,15]. The manufacturing process for PWB includes metallization (plating or lamination), etching, photolithography, multilayer lam- ination, and via interconnection [16]. These steps are similar to silicon-based processes as well as to ceramic multilayer processes, and our work takes advantage of these similarities. The mate- rials and the overall fabrication process for PWB, however, are lower in cost and higher in throughput, respectively, when com- pared with silicon manufacturing processes since the PWB typically uses an 18 in. × 24 in. glass fiber reinforced polymer panel as com- pared to a 12-in. diameter silicon wafer. The PWB materials are more mechanically robust when compared with ceramics and glass. In addition, they are also more chemically inert than low tem- perature co-fired ceramics (LTCC), where oxides may leach out in aqueous media. In recent years, the PWB has evolved from a simple circuit board substrate to a high density interconnect (HDI) framework, where the conductor lines and spaces have been reduced to between 50 and 75 m, with microvias in the same 0925-4005/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2009.01.071