CCD based pH imaging sensor

Abstract

We propose and demonstrate a novel pH imaging sensor based on the CCD (Charge Coupled Device) technology. This device consists of pH sensing parts, which sense pH value and transform a pH value to electric charges, and conventional CCD parts, which transfer the electric charges to read out circuit. A thin Si3N4 film which acts as the hydrogen ion-sensitive membrane was used in the pH sensing film. The prototype devices were fabricated. The output signal fiom the imaging sensor was lineally changed from pH0 to 14, and successfully observed a pH image on a black & white TV monitor.

Intelligent Ultraviolet Sensor Composed of GaN-Based Photodiode and N-Channel Metal Oxide Semiconductor Si-Charge Transfer Type Signal Processor

“…The PD modifies the surface potential for the Si nMOS channel and this potential change is read out by the charge transfer technique and floating diffusion. The amount of output potential change ÁV out of the Si signal processing circuit is given by 23) ÁV…”

“…where C SENS is the electrostatic capacity of the sensing area, C FD is the electrostatic capacity of floating diffusion, and Á' sig is the amount of change in surface potential, which is proportional to the difference in input signals at the sensing area. [23][24][25] The GaN-based PD wafer, separated from the substrate by the laser lift-off technique, 26,27) is bonded using metal on the Si-MOS wafer, in which the source/drain and gate oxide are fabricated. The bonding metal is used as a gate electrode.…”

“…This charge transfer type surface potential sensor is the one to which the principle of charge-coupled device (CCD) was applied and was originally used to measure the distribution of pH. [23][24][25] However, it is not limited to only a pH sensor; all surface potential change applied to the gate electrode can be detected by changing the structure of the sensing part. The function of a UV sensor can be achieved by changing the Si 3 N 4 layer for the ion sensing part of the pH sensor to a PD.…”