Profile of a Touch-Down solution to a nonlocal MEMS model with critical parameters

Abstract

This work investigates a mathematical model arising in the study of MEMS devices, described by the following parabolic equation on $[0,T)\timesΩ$: $$\partial_t v = Δv + \fracλ{(1-v)^2\left( 1 + γ\int_Ω \frac{1}{1-v}\, dx \right)^{2}} , \qquad 0 \leq v \leq 1,$$ where $Ω\subset \mathbb{R}^N$ is a bounded domain and $λ, γ> 0$. We construct a solution with a prescribed profile, which quenches in finite time $T$ at exactly one interior point $a \in Ω$. Moreover, we are able to provide an asymptotic description of the quenching profile. We reformulate the problem as a blow-up problem to utilize the techniques employed in Merle, Zaag in 1997, Duong, Zaag in 2019 and Duong, Ghoul, Kavallaris, Zaag 2022. The proof proceeds through two principal steps: a reduction to a finite-dimensional dynamical system and a classical topological argument employing index theory. The main challenge lies in managing the nonlocal integral term, which generates an additional gradient term when the problem is transformed into the blow-up framework.