M.Sc Thesis

M.Sc StudentSun Jiaxing
SubjectTime-Resolved and Self-Accommodating Hybrid Functional
Fabric Sensor for Decoupling Multiple Stimuli from
DepartmentDepartment of Chemical Engineering
Supervisor PROF. Hossam Haick
Full Thesis textFull thesis text - English Version


Multi-parametric sensing devices have the potential to be in the forefront of a new generation of applications in a wide variety of fields. Nevertheless, the use of these devices in the real complex environments is limited by selectivity, namely the ability to decouple the co-existing stimuli. In this thesis, it is presented a time-resolved sensing device which is made from a mixture of elastic polymer SEBS with dispersed hexanethiol-coated gold nanoparticles (AuNPs; ~10±1 nm in diameter) on top of MEDI-FIX medical fabric that was covered beforehand by Single Wall Carbon Nanotubes (SWCNTs; so called, sensor A). For this device, a dimension of ''time'' is introduced through recording signal variations under continuous stimulation/ relaxation in the dwelling time interval. For the sake of comparison and understanding the underlying sensing mechanism, this sensor A was compared with a series of sensing fabrics in which each element was systematically knocked out, more specifically the sensors without SEBS polymer (sensor B); without fabric element (by replacing fabric by Kapton substrate with 100-µm gold electrodes; sensor C); without AuNPs (sensor D); and without SWCNTs (sensor E). The results have shown that sensor A endows diversified time-resolved sensitivity to gases, pressure and bending. The time-resolved insensitivity to bending gives the unaffected sensitivity to humidity and pressure on different curving surfaces. Bending-caused shift of pressure signal and normalized humidity exposure signal did not exceed 3.5 and 2.8%, respectively. In contrast, none of sensor B-E showed similar selectivity/time-resolved insensitivity. To digitally decouple the multiple signals received from sensor A, the signal patterns of bending, pressure and RH exposure were modeled by respectively sum and difference of lognormal Gaussian distributions, and enzymes and substrates interaction. In particular, the regressed responses to the same pressure amplitude on different curving surfaces were showed to closely coincide. In all, this time-resolved sensing strategy with simple readout for decoupling could be important in wearable sensors for health diagnosis, quality control, etc., in especially complex environments characterized with movements or vibrations.