Partial Weight-Bearing (PWB) regime is a part of a recreation process for patients with lower limb fractures/strains/sprains. In order to avoid a frequent foot overloading and achieve better patient compliance with requirement of PWB, the application of Weight-Bearing Monitoring System (WBMS) is highly attractive. However, it is challenging to find an affordable material for protective insole cover that is also a good shock-absorber. In this regard, a new formulation for protective covering material that preserves and isolates the sensors of WBMS device is suggested in this thesis. Twenty one samples of renewably sourced Polyurethane Foam (PUF) composed of poly (trimethylene ether) glycol (PO3G) and unmodified castor oil (CO) were synthesized and evaluated according to predetermined criteria. Response surface methodology of Box – Behnken design was applied to study the effect of the following parameters (polyols ratio, isocyanate index (II), and blowing agent ratio) on the properties (hardness, density) of PUFs. Results showed that CO/PO3G/TDI PUFs with hardness Shore A 17-22 and density of 0.19-0.25 g/cm3 demonstrate the required characteristics and can potentially be used as a durable and functional insole material. Phase separation studies have found the presence of well-segregated structure in PUFs having polyols ratio CO:PO3G 1:3 and low II, which further explains their extraordinary elastic properties (400% elongation). Analysis of cushioning performance of PUF signified that 5 samples have Cushioning Energy (CE) higher than 70 N·mm and Cushioning Factor (CF) in the range of 4-8, hence are recommended for application in WBMS due to superior weight-bearing and pressure-distributing properties. Moreover, the developed formulation undergoes anaerobic soil bacterial degradation and can be categorized as “green” bio-based material.