# Microheater Topology for Advanced Gas Sensor Applications with Carbyne-Enriched Nanomaterials
## 3 Results
Figure 3: Piezoelectric properties of the LiNbO\({}_{3}\) substrate at different temperatures. To explore the response characteristics of the sensors with the three microheaters topologies, their output voltage attenuation vs. input reference signal was measured and the time delay of the output electric signal referred to the input one was determined for two cases: the first detection of ethanol with concentration in the range of 180-680 ppm (before heater activation) and the next detections after the heaters were periodically switched on to desorb previously absorbed molecules. The curves related to the activated heaters are averaged from five consequent desorbing cycles. The difference between the separate measurements is less than 1%, which falls into the tolerance of the fabrication process accuracy. Figure 5 shows the time delay and voltage attenuation of the sensor with the small meander microheater before (a) and after activating the heater (b). The attenuation of the output voltage \(\Delta\)V compared to the input reference signal was in the same range before and after the activation of the small meander microheater. Therefore, the meaningful quantity for the sensor recovering estimation can be the time delay \(\tau\) between the two signals. Figure 5 also shows the time delay and voltage attenuation of the sensor with the large meander microheater before (c) and after activating the heater (d). The maximum attenuation of the output voltage after desorption increased by approximately 100 mV,  
Figure 4: (a) Comparison of the contact resistance and interface capacitance changes before and after heating for the three microheaters topologies; (b) change in sensing layer resistance over time at different microheater topologies. which can be related to a change in the carbyne adsorption capacity due to the induced redistribution of the waves because of the broader thermal field spot, which can be related to alterations in the viscoelastic properties of the materials due to the broader thermal field spot. It could impact the acousto-electric transformation and lead to such a great change in the output voltage attenuation. Another possible explanation is that the altered thermal field may influence the adsorbate-surface interaction, potentially leading to enhanced adsorption or desorption kinetics and altering the acoustic properties of the surface [26]. Figure 5e,f show the time delay and voltage attenuation of the sensor with the dense rectangular microheater before and after activating the heater, respectively. The maximum attenuation of the output voltage after desorption increased by approximately 60 mV, and its absolute value is greater than for the two meander structures, which is related to the narrow dynamic range of the sensor. Figure 6a shows the degree of recovery of the initial sensor state, or sensor hysteresis in the case of the small meander geometry of the microheater. The deviation of \(\tau\) from the initial value is 3.3% at the beginning of the measurement for low concentrations, 2.7% at the end of the measurement for high concentrations, and 2.3% in the range of 450-600 ppm (with no difference at 550 ppm), where the sensor response is linear, and its sensitivity is the greatest (the highest slope of the characteristic). The hysteresis is narrow, and it can be concluded that there is a satisfactory degree of recovery in the sensor properties after desorption, indicating the appropriate topology of the microheater and a proper technological flow that does not affect the other layers. The microheater successfully performs its function to cause the desorption of ethanol molecules without causing a local concentration of heat, which could induce defects in the crystal lattices of the materials and affect the sensitivity or dynamic range of the sensor. The power consumption of the microheater is 1.92 mW. Figure 6b shows the degree of recovery of the initial sensor state for the large meander microheater topology.