## 1 Introduction
The use of pieces with reduced dimensions has increased in the last years through several markets. Microinjection is being used in a commercial way and good results have been achieved, this technique is inefficient, and the production costs are high. Microinjection is based in a simplistic adaptation of a conventional injection machine to produce micro samples and is not optimized to mold samples with nano or microscale features. The material dosage and heating is poor and not well optimized, leading to a high amount of non-useful material, long cycle times, and an inefficient heating profile [28; 29]. Recently, some studies have been focused on the development of a new promising technique based on ultrasound micromolding [30]. Advantages include its good reproducibility, low cost, efficient material dosage, low cycling time, and high resolution [31]. The sample is locally heated by the kinetic energy produced by the chain vibration that is induced by an ultrasonic source [32; 33; 34]. Ultrasound heating also increases the flow index of the polymers leading to an effective filling of designed micromold cavities if an appropriate pressure/force is applied [35]. Different studies have been carried out with some commodities, such as polyethylene, polymethylene oxide, and polypropylene, [32], commercial biodegradable polymers such as polylactide (PLA) and polybutylene succinate [36], and polymers loaded with exfoliated clays (e.g., PLA) [37] and multiwall carbon nanotubes (e.g., polycaprolactone) [38]. All of them concluded that an accurate selection of amplitude, force and time parameters could lead to minimum polymer degradation, absences of defects in the micromolded pieces, and an accurate filling of the mold. In this work, PLA was selected as the polymer matrix due to its biocompatibility, low immunogenicity, and good mechanical properties. PLA is FDA-approved for clinical use and has the ability to biodegrade in lactic acid into the human body. PLA has already been used to fabricate medical implants like screws and pins [39], scaffolds [40], and drug-delivery systems [41]. Moreover,our previous works have demonstrated that ultrasonic-assisted molding is an adequate process to produce miniature pieces loaded with bactericide agents without activity loss [42]. This is a key point since it is well known that production methods can influence on the pharmacological activity. The main goal of the present work is the preparation of new biodegradable porous scaffolds through an ultrasonic-assisted micromolding technology as a new indirect method suitable to be employed at an industrial scale with an extremely high resolution. In addition, we have explored the capacity to load the porous scaffolds with a pharmacological agent. In this case, an antibacterial drug able to protect against potential infections has been selected. The crucial point concerns the retention of the drug during the necessary salt leaching step. The work involves three main parts: evaluation of the effects caused by the incorporation of porogenic agents, optimization of the leaching process, and evaluation of the capacity to load a representative drug. Thus, the achievement of antimicrobial properties for the triclosan (TCS) loaded scaffold could be considered as a good probe of the suitability of the new application of ultrasound technology to prepare porous scaffolds.