OBJECTIVE: Acoustic reconnaissance for Army applications has had limited usage due to the large size of the transducer arrays required for beamforming. The objective of the Phase I is to perform a feasibility study of a transducer technology that can be integrated with flexible substrates for applications in compact acoustic beamforming arrays. DESCRIPTION: Acoustic reconnaissance has a variety of unique capabilities including spoofing immunity, ability to penetrate clutter, unique signature identification, jam resistance, low cost, low weight, and minimal power consumption[1, 2]. Acoustic arrays not only provide directional information but also limit background noise due to wind and other locally decorrelated noise. The significant disadvantage of acoustic reconnaissance is the size of the array. Direct size reduction of the individual transducers results in decreased sensitivity, increased noise floor and correspondingly poor sensor performance. Recent developments in acoustic transducers have indicated several promising materials for reducing the size of acoustic transducers and most are compatible with current processing technologies. As a result, the potential for compact acoustic transducers on flexible substrates is realistic in the near future. In conjunction with new transducer technology is the recent development of acoustic metamaterials[5, 6]. Acoustic metamaterials have the potential to enhance the signal by controlling and directing the incoming acoustic waves and aid in the size reduction of the overall array. The main objective of this solicitation is to investigate material solutions to reduce the size of transducer arrays without a large reduction in the sensitivity. The array itself should be flexible for the widest possible range of applications, including unmanned aerial systems. Incorporation of acoustic metamaterials is expected to aid in the sensitivity of the array. Frequency range of interest is 20Hz to 20 kHz. This solicitation is aimed at the development of the transducer array. The advancement of signal processing techniques is beyond the scope of this task. PHASE I: Conduct a feasibility analysis of a flexible, compact, transducer array for acoustic beamforming. The transducers should be compatible with current microfabrication techniques. PHASE II: Design and fabricate a prototype transducer array on a flexible substrate for acoustic sensing applications. Perform basic testing of the transducer parameters including sensitivity and noise floor. PHASE III: Develop a manufacturing plan for transition from prototypes to initial production that is producible with a manufacturing process such as a wafer scale process to reduce components costs. Low cost, compact acoustic transducer arrays that can be applied on a variety of surfaces have numerous dual use applications including collision avoidance for automobiles, imaging, and communications. Collision avoidance of unmanned aerial systems is currently achieved with the aid of RADAR and optical sensors. However, the availability of the RADAR in the battlefield may be limited. Optical sensors often tend to yield falls results in identifying incoming UAS. Therefore, acoustic sensors can be used to augment the existing detection technologies. The flexible acoustic sensors can be mounted on a curved surfaces of the aircraft wing. Unattended ground sensors currently used in the battlefield are mounted on flat surfaces and they have to be deployed manually. Sensors mounted on curved surfaces (e.g. spherical) can be air-delivered.