The use of multiple channels in wireless sensor networks helps avoid interference and increases the overall network throughput. In addition, introducing multi-interface nodes further helps in increasing the packet delivery rate for those specific nodes. In this paper, we propose a channel allocation method that takes into consideration the existence of multi-interface nodes in a multi-hop wireless sensor network. It is based on HMC-MAC, a hybrid MAC protocol that uses CSMA/CA, for data exchange, TDMA sequencing nodes activity and FDMA for allowing simultaneous collision free exchange. We evaluated our method using NS2 simulator and results show that our MAC protocol improves the overall network performance compared to other protocols with periodic high data rate traffic and burst traffic.