Active cmos sensorarray for Electrochemical Biomolecular Detection<br />12<br />
<ul><li>* Introduction* electrochemical sensing* active cmos sensor design* LIMITATION OF CMOS* conclusion</li></li></ul><li>A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument.Cmos array miniaturizes the sensing platform, enhance portability,enabling high throughput ,highly parallel analysis.<br />
Electro chemical sensing approaches to DNA detection , rely on detecting changes occurring with hybridization at interface.<br />CMOS sensor include :<br /><ul><li>A sensor chip interfaced to a single on-chip WE.
Electrochemical sensing<br />1. Potentiostat operation<br />2. Cyclic Voltammetry<br />Feedback control system.<br />Apply desired potential to elctrochemical cell.<br />Measure the movement of charge.<br />Low speed , large signal tech.<br />Detect redox species.<br />Determine probe concentration , measure DNA probe target hybridization.<br />
Description of potentiostat operation. <br />(a) Conceptual diagram. (b) Implementation using electronic components.<br />
Active cmos sensor array design : Each array consist of square gold (WE)having side length 100 µm. Variation allows effect of electrode area on the cell current for different redox and biomolecular reaction. Dual slope ADC. <br />
1. Electrochemical cell model Small signal model simulate system behavior and test potentiostat stability when chip is operated in electrolyte. 2. Potentiostat circuits To provide good noise performance stability across wide range of operating condition.3. Chip post processing & Experimental setup Used to create an array of Au elect. on the surface. packaged chip in PCB socket with top plate layer. <br />
. <br />Small-signal circuit models of <br /> (a) the electrode–electrolyte interfaces <br /> present in an electrochemical cell and <br /> (b) the WE–electrolyte interface augmented with noise sources.<br />