| The lab-on-chip (LOC) technology could transform and greatly enhance the health care system by making genetic diagnosis tests fast, accurate and readily accessible. However, most LOC systems are not prepared to resist variations of their external environment, as they depend upon many uncontrollable boundary variables. This dependence causes alterations of the temperature profile of the system. In critical applications that require precise temperature control, such as genetic diagnosis for disease detection, or in portable devices in which adequate thermal isolation is difficult to provide, those alterations degrade the reliability of the system. Expensive infrastructure is then required to maintain repeatable external conditions. Moreover, costly and invasive calibration methods are required to estimate the true temperature in the system. These challenges prevent the cost-effective manufacture of LOC systems.;We have developed a new thermal control technology to produce manufacturable LOC systems. In this approach, the system depends upon a single dominant external variable that can be easily controlled, making the system robust to all other external variables. Operation in uncontrolled environments with minimum infrastructure is then feasible. With this concept we built a LOC system for genetic amplification in a new polymer chip architecture. In this system a thin film heater that is also a sensor is highly integrated to the reaction chamber. This integration plus the homogeneous temperature provided by the heater results in unusual temperature sensing accuracy, and a greatly simplified calibration process. By keeping tight microfabrication tolerances, the repeatability of the system is further ensured, eliminating per-device calibration. Reducing the complexity and cost of calibration to this level allows for mass production of ready-to-use, affordable devices. Other technologies that support our robust control approach were also developed, including an automated method to precisely distribute heat in the system space. This method enabled the use of aluminum for the fabrication of planar heaters/sensors, replacing expensive metals that are commonly used. The use of aluminum makes our technology CMOS-compatible. CMOS integration will enable a fully contained system that could be packaged in a USB key and cost a few dollars. Such a system would certainly revolutionize the practice of Medicine. |
