Metal oxide nanoparticle gas sensors showpromise due to their high sensitivity towards a wide range of gases, low costs, and low complexity. Particle sizes at nanometers offer a high surface-to-volume ratio which provides more areas on the surface where reactions can occur. This work presents the application of spark ablated nanoparticles on chemiresistors and chemFETs, and does a study on whether spark ablated nanoparticles are a viable alternative to nanoparticles generated using other methods. The focus in this thesis is on pure metal oxide nanoparticles without any addition of dopants or decorations. Devices are fabricated with different interdigitated electrode dimensions. The effect of electrode width and gap size on the gas response is studied by comparing the sensing performance of the devices. In this work, a very high sensitivity of 1300% is achieved towards 35% relative humidity using a 1x1 mm device with SnO2 nanoparticles. Towards 20 ppm of ethanol, sensitivities of 39% and 67% are achieved using 1x1 mm and 4x1 mm devices with SnO2 nanoparticles respectively, which implies that spark ablated nanoparticles could be a viable alternative to particles generated using other methods. The full recovery time after gas exposure seems to be very long and takes around an hour for some devices at 200 °C. Possible solutions for this are setting a higher temperature (not possible with the used setup), or reducing the particle size (∼20 nm in this study). The electrode finger widths and gap sizes are varied between 2-15 μm for each device. However, no correlation is found between electrode geometry and gas response within this range, suggesting that differences in gas response between devices likely stem from nanoparticle layer quality differences.

Endoscopic devices are used in the medical world to inspect the gastrointestinal tract. Because there are some complications with wired endoscopy, such as reaching the small intestine, there is a need for new methods to do endoscopy. Therefore an endoscopic pill is invented which can be used to do measurements in the gastrointestinal tract. This endoscopic pill is a small device with small sized electronic sensing elements. This thesis goes through the implementation process of sensors inside an endoscopic pill in order to be able to perform measurements inside the human body. The sensors used in the endoscopic pill are a temperature and a pressure sensor. Besides that, this thesis also goes through the design process of the 3D design of the capsule, which is later 3D printed. The goal of the project is to make a prototype which contains functioning sensors and which can be made swallowable during future work.