 This paper examined the effects of liquid level on microwave resonance sensing using a flexible polydomethylsiloxane, PDMS, microfluidic channel, and soft tubing. Numerical simulations and experiments were conducted to study both contactless and contacting sensing scenarios. In contactless sensing, the resonance frequency varied sensitively with the liquid level, while in contacting sensing, a spoof localized surface plasma resonator was used to improve the detectability of hypermativity and high loss aqueous solutions. This work provides general guidelines for understanding and controlling the resonance sensors in aqueous environments, and helps to realize further lower detection limits. This article was authored by Wanzhou Wang, Xuanru Zhang, Longfei Zhang, and others.