Component Design Materials Processing GLUCOSE SENSOR Blood flows into the hollow areas inside the sensor.
Component Design Materials Working Glucose Sensor To Flow sensor Blood enters Pyrrole is deposited Pt counter electrode Ag reference electrode Pt working electrode Three sensing electrodes, including a working (platinum, Pt), a counter (Pt), and a reference (silver, Ag) electrode, were designed and fabricated by using thin-film deposition process. A constant current (2.483 μA) was applied to electropolymerizedpyrrole and used to entrap glucose oxidase on the surface of working electrode for electrochemical sensing of glucose. Then the electrochemical process takes place with 0.7 volt of voltage applied to the electrodes
Component Design Materials Processing Glucose Oxidase was used to react with the blood glucose to electrochemically measure reaction currents (GOD Glucose oxidase ) Then, the operation of the glucose sensor is based on electrochemical oxidation of hydrogen peroxide to regenerate oxygen, which thus completes the enzymatic cycle. H2O2 -> 0.7 V Pt with Ag/AgCl -> 2H+ + O2 + 2e− The amperometric method is used to convert this second chemical reaction into a current signal And this current signal has a threshold which drives the micro pump in the insulin reservoir **reference 7
Highly transparent in UV region allowing fabrication of relatively thick structures
Step 1: Heated, to remove any water on the surface and then oxidised to form silicon dioxide. Step 2: Wafer is coated with photoresist by spin coating Step 3: Wafer is exposed to UV light through a photomask Step 4: Photoresist can now be stripped off and the oxide layer can be etched away using a suitable etchent Step 5: Now the photoresist is no longer needed and can be removed using a liquid resist stripper
Component Design Materials Working Based on hot-film anemometry. Platinum thin-film resistor is used for detecting the varying amounts of current flowing through the chip. The resistors are located in the centre of the oxidised porous silicon diaphragm and the rim of the chip, respectively. When the current is able to overcome the resistance then the flow sensors let the fluid flow. Flow Sensor Flow sensors were composed of Pt and Au (gold) materials with a resistance of 120. The temperature sensitive flow sensors can detect the flow rate based on their resistance change.
Why Polydimethylsiloxane (PDMS) 5 Basis of the upper microfluidic control module consists of micropumps, microvalves and microchannels is a molecule called polydimethylsiloxane (PDMS) PDMS is a resilient material, it is an ideal choice for the current pneumatic micropumps, in which the application of compressed air causes the PDMS membranes to deflect peristaltically, hence driving the sample through the microchannel. 6 A Viscoelastic materials At high Temperature At low Temperature
Component Design Materials Processing Microfluidic PDMS based microchannel SU-8 photoresist is deposited over a pre treated and etched Silicon subsrate. PDMS layer is then deposited C) Silicon substrate is removed D) Then this pneumatic chip is spread over the silicon substrate, the substrate is lined with PDMS E) Finally the silicon substrate is removed
Component Design Materials Working Actuator Device S-shape pneumatic microchannel intersects the fluidic microchannel at various points along its length. Thin PDMS membranes are located at each intersection and are deflected as compressed air travels through the S-shape microchannel. Compressed air travels along the lower S-shape microchannel and causes the PDMS to deflect The time-phased deflection of neighboring membranes induces a peristaltic effect which drives the fluid along the microfluidicmicrochannel.
Component Design Materials Processing Actuator Device (1) Spin-on of SU-8 (2) photolithography (3) PDMS casting (4) oxygen plasma treatment and bonding (5) bonding of PDMS and sensor electrodes.
Component Design Materials Processing (1) The SU-8 negative thick PR is spun-coated on a silicon wafer. S-shaped micropump (2) A standard lithography process is used to form the SU-8 structured mold. (3) PDMS is poured on the SU-8 microstructure mold and then cured. (4) PDMS inverse structures are formed and mechanically peeled off the mold. (5) A microflow sensor is formed using the standard lithography and E-beam evaporation processes. (6) Oxygen plasma treatment is performed prior to bonding PDMS layers and the glass substrate to form the completed S-shape micropump.