A Novel Inkjet Printed Surface Enhanced Raman Spectroscopy (SERS) Substrate for the Detection of Toxic Heavy Metals

AbstractA novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a silicon (Si) wafer using a 400nm inkjet printed thin film of silver (Ag) nanoparticle ink, with 150nm particle size. The capability of the fabricated SERS substrate for detecting toxic heavy metals such as mercury sulfide (HgS), cadmium sulfide (CdS) and zinc oxide (ZnO) was demonstrated. The SERS based response of the printed substrate produced an enhanced Raman signal when compared to that of target molecules adsorbed on bare Si wafer. An amplification of the SERS intensity by an order of 3 to 5 times was observed for all test samples, due to the presence of hotspots between the metal nanoparticle aggregates. The responses demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals

Fully Printed Flexible Humidity Sensor

AbstractA humidity sensor that employs interdigitated capacitors (IDC) printed with silver (Ag) nanoparticle based ink on a flexible poly ethylene terephthalate (PET) substrate was successfully fabricated using gravure printing process. Thicknesses of 1μm and 500μm of a humidity sensitive polymer poly (2-hydroxyethyl methacrylate) (pHEMA) was deposited on the IDCs by means of gravure printing. The capacitive response of the sensor towards relative humidity (RH) was measured in the range of 30% RH to 80% RH; the maximum percentage change in capacitance was 172% at 80% RH when compared to base capacitance at 30% RH. The humidity response of the printed sensor revealed a very high stability with a maximum error of 0.6% and 0.8% from the average value at 40% RH and 60% RH, respectively