Papers by Keyword: ISFET

Abstract: Sodium chloride, commonly known as table salt, is widely used as essential seasoning in food, snacks and deserts worldwide. However, excessive consumption of table salt is a major cause of various health issues, involving high blood pressure, liver cirrhosis, kidney disease, and heart failure. This research aims at creating a portable, low-powered, efficient sensor for detection of sodium ions in body plasma for medical diagnosis purpose. The device was fabricated on a platform of Ion-Sensitive Field-Effect Transistor (ISFET) modified with sodium ionophore (sodium recognizing element), entrapped in polyurethane thin film. Our preliminary studies show that sodium ionophore-modified ISFET sensor yields good sensing performances, having a maximum sensitivity of 43 mV/pNa, and a detection limit of 2.3 millimol/liter.

Abstract: This research studied the effect of ion implantation on electrical properties of ISFETs. In the experiments the sensing membrane area were implanted with 3 types of ions (Boron(B), Phosphorus(P), and Arsenic(As)). After the implantation without annealing, the IV-characteristics of Source/Drain (P-N junction) of ISFET were performed and compared with the behaviour before implantation. In addition, the response to acid-alkaline (sensitivity) of ISFET were also studied. From the results the leakage current of source-drain, P-N junction like, decreases significantly after the implantation. However, this process damaged the devices so that the response to acid-alkaline are lost.

Abstract: In this work a micro flow sensor, using a double gate Ion Sensitive Field Effect Transistor (ISFET) and two metal electrodes, for fluid flow rate measurement in micro-channels were fabricated and demonstrated. By the channel fabrication the molds were patterned reversely on a silicon wafer using Deep Reactive Ion Etcher (DRIE). The double gate ISFET and two metal electrodes were placed on the mold in the distance 15 millimeters. The channels were formed using polydimethylsiloxane (PDMS) from the mold with the width 1000 and 2000 micrometer and the depth of 250 micrometer. After removing PDMS from the mold the channel was bonded with glass substrate by RF plasma technique. By the verification of flow sensors working range water and one mole of sodium nitrate solution were alternated in flow channel. The fluid flow rate were compared with the flow rate from weighing. It found from the comparison that the high deviation was found at low flow rate. Furthermore, the deviation depends also on the dimension of the flow channel.