Integrated micro-device for isothermal DNA amplification with on-chip bioluminescence detection

A lab-on-chip device for the isothermal amplification of DNA based on loop-mediated isothermal amplification (LAMP) technique coupled with Bioluminescent Assay in Real Time (BART) technology is presented. The device is composed of a PDMS microfluidic network coupled to a glass substrate on which thin film sensors and actuators are fabricated. The glass substrate includes a thin-film resistive heater on one side and multiple thin-film sensors on the opposite side in contact with the PDMS part. The sensors are hydrogenated amorphous silicon (a-Si:H) diodes deposited in a single deposition run and then specialized for temperature or radiation sensing by changing the top electrode material and by using different bias conditions. The temperature sensors have a top metal contact in order to prevent radiation reaching the junction while the photosensors have a top transparent ITO contact. Accurate temperature measurement is achieved exploiting the linear relation between temperature and junction voltage drop when the diode is biased in forward condition with a constant bias current. The photosensors, instead, are kept in reverse conditions at constant reverse bias voltage in order to achieve a linear relation between incident radiation intensity and measured photocurrent. Dedicated electronics is employed to control the chip temperature along the whole experiment and read-out the photosensor currents. Test experiments performed with parvovirus B19 DNA samples demonstrate the correct chip operation proving the ability to discriminate different concentrations of viral DNA with an excellent agreement with standard off-chip methods,