Osteoarthritis (OA) is one of the most common human diseases, and the occurrence of OA is likely to increase with the increase of population ages. The diagnosis of OA is based on patientrelevant measures, structural measures, and measurement of biomarkers that are released through joint metabolism. Traditionally, radiography or magnetic resonance imaging (MRI) is used to diagnose OA and predict its course. However, diagnostic imaging in OA provides only indirect information on pathology and treatment response. A sensing of OA based on the detection of biomarkers insignificantly improves the accuracy and sensitivity of diagnosis and reduces the cost compared with that of radiography or MRI. In our former study, we proposed microfluidic platform to detect biomarker of OA. But the platform can detect only one biomarker because it has one microfluidic channel. In this report, we proposes microfluidic platform that can detect several biomarkers. The proposed platform has three layers. The bottom layer has gold patterns on a Si substrate for optical sensing. The middle layer and top layer were fabricated by polydimethysiloxane (PDMS) using soft-lithography. The middle layer has four channels connecting top layer to bottom layer. The top layer consists of one sample injection inlet, and four antibody injection inlets. To this end, we designed a flow-balanced microfluidic network using analogy between electric and hydraulic systems. Also, the designed microfluidic network was confirmed by finite element model (FEM) analysis using COMSOL FEMLAB. To verify the efficiency of fabricated platform, the optical sensing test was performed to detect biomarker of OA using fluorescence microscope. We used cartilage oligomeric matrix protein (COMP) as biomarker because it reflects specific changes in joint tissues. The platform successfully detected various concentration of COMP (0, 100, 500, 1000 ng/ml) at each chamber. The effectiveness of the microfluidic platform was verified computationally and experimentally.
This paper presents the fabrication and test of a flexible luminous device using hollow cathode discharge. The discharge
device consists of three layers which are a thin anode layer, an insulation layer and a hollow cathode layer. The device
has an array of 10 x 10 holes for the emission. The hole diameter and depth are 100 μm and 120 μm, respectively. The
hollow cathode discharge occurs between two electrodes. The hollow cathode discharge usually has the characteristics
of the high current density. The discharge device is fabricated by micromachining technology. The anode and the
cathode are aluminum and nickel, respectively. Polyimide is chosen as an insulating material because of an excellent
dielectric property and a good mechanical stability. The anode of aluminum is deposited by thermal evaporator.
Polyimide is spin coated and the hollow cathode is fabricated by nickel electroplating. The thickness of the flexible
luminous device is about 150 μm and total size of the device is 20 mm x 10 mm. The discharge test was performed in
argon gas chamber at room temperature for various pressures. The current is measured during the discharge to various
applied voltages. Current-voltage characteristics of the device were obtained for the operation voltage ranging from 250
to 300 V. The discharge appears at the applied voltage of 260 V in 360 torr. The discharge is also observed at the
atmospheric pressure. Compared with a macro discharge device, this device operates at much higher pressure, even at 1
atm. The discharge test confirms that the fabricated device is feasible for a flexible display operating at the atmospheric