Introduction

The main challenges of photovoltaic solar cells today stem in the complexity of manufacturing, the low energy conversion efficiency, the price and the low long-term benefit yield. Moreover, the latter is more pronounced when it comes to maintenance and recycling. In the past five years, the scientific community pointed halide perovskites as promising compounds for photovoltaic applications \cite{Lee_2012}\cite{Luo_2014} due to the high photon to electron conversion efficiency, low price, and the simplicity of device architectures. The CH3NH3PbI3, (abbreviated as MAPbI3), was the most commonly used and developed material. Nevertheless, its lead content raised much more concerns\cite{Benmessaoud_2016} regarding health hazards during handling and processing, as well as its potential toxic release into the environment. Therefore, active research in materials science, chemistry and physics is currently developing novel materials, which could be non-toxic but still having high conversion efficiency. The CH3NH3SnI3, (hereafter MASnI3), was proposed as such by the scientific community. However, tin is also a heavy metal which could be toxic in specific forms \cite{Blunden_2003,Browne_1974,22931871}. There is an emergency in verifying their potential toxic effects since they are promised to be on the market in 2018 (cite dyesol nesli and oxford).
We have shown recently by in vitro studies how these perovskites can impact human cells(tox. Res. 2016 and paper snami in vitro-in preparation), and the group of Conings claimed to report the toxic effects of a sister compound, the non-photovoltaic and  commercially available PbI2  and SnI2 on zebrafish(cite alibaba). Here, we report on the severe toxic effects for both MAPbI3 and MASnI3 by in vivo study on Caenorhabditis elegans (C. elegans) using a microfluidic platform.
C. elegans is a free living, non parasitic soil nematode that can be cheaply and easily cultivated in the laboratory, where it is grown on agar plates with liquid cultures of E. coli as the food source. The 1 mm long organism is transparent, which facilitates organs observation and dissection, and can be housed in large numbers (10’000 worms per Petri dish). Its life span is about 3 weeks and its genome has been fully sequenced and annotated.(Sulston & Brenner, 1974) The adult body-plan is anatomically simple with 959 somatic cells and produces up to 300 eggs per adult. It reproduces within a life cycle from egg to young adult of about 3 days under optimal conditions. Another key advantage of C. elegans model is that feeding by RNAi facilitates gene silencing\cite{11178279}.