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Microneedle (MN)‐based diagnostic devices can efficiently access skin interstitial fluid (ISF) for accurate and minimally invasive detection of health‐related biomarkers. This work reports a biomarker (i.e., glucose or alcohol) monitoring MN device that is composed of swellable MNs and electrochemical test strip. This device is constructed by adhering MN patch on the electrochemical strips using the chitosan as the connecting layer. The MNs penetrate the skin for extraction of ISF that flows to the backing layer of MNs and is analyzed by the test strip. In the in vitro skin models, this device accurately detects the glucose from 0 mM to 12 mM and alcohol from 0 mM to 20 mM. In vivo experiment shows this MN device is capable of minimally invasive sampling of ISF and analysis of glucose levels to determine the glycemic status of mice.

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Releasing sterile mosquitoes is a method of mosquito control that uses area-wide inundative releases of sterile male mosquitoes to reduce reproduction in a field population of wild mosquitoes. In this paper, we consider a mosquito population model with a nonlinear saturated release rate of sterile mosquitoes and study the complex dynamics and bifurcations of the model. It is shown that there are a weak focus of multiplicity 3 and a nilpotent cusp of codimension 4 for various parameter values and the model exhibits Hopf bifurcation of codimension 3 and Bogdanov-Takens bifurcation of codimension 2 as the parameter values vary. Our analysis also shows that there exists a critical release rate coefficient of sterile mosquitoes, above which the mosquito population can be eliminated and below which the interacting sterile and wild mosquitoes coexist in the form of multiple periodic oscillations and steady states for some initial populations. Numerical simulations are presented to demonstrate the coexistence of a homoclinic loop and a limit cycle, the existence of two limit cycles, and the existence of three limit cycles, respectively.

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