Biomedical Mechatronic Dynamometer to Support the Evaluation of the Effects of Leprosy Through the Palmar Holding Strenght and the Tweezer Holding Strenght

Abstract

The hand can suffer the effects of several diseases among the most serious, leprosy stands out, which is considered infectious and can generate loss of muscle strength, atrophy, deformity and physical, mental and social disability. For the World Health Organization (WHO) and also doctors and physiotherapists, it is necessary to evaluate the diseases in an objective, reliable and early manner in order to propose appropriate treatment and follow their evolution. This research proposed a biomedical mechatronic dynamometer in order to support the evaluation of the effects of leprosy by means of palmar grip strength and grip strength of tweezers performed by hand. The experimental research was developed at the Federal University of Mato Grosso do Sul and consisted first of all in the survey of the demands of the health area in relation to the biomedical dynamometer being consulted the following databases: Medical Literature Analysis and Retrieval System Online (Medline); US National Library of Medicine National Institutes of Health (PUBMED) e Institute of Electrical and Electronic Engineers (IEEE). The mechatronic biomedical dynamometer consisted of three fundamental parts: mechanical structure, electronic signal conditioning circuitry and digital information processing. The mechanical structure was designed to withstand a strenght of up to 700 N, developed in brass because this metal has low cost, has less mass and also because it is easier to machine than steel. The oval shape of the structure contains two lateral and thin regions that measure 2 cm thick, 3 cm wide each and aim to concentrate mechanical stresses in order to sensitize the strain sensor consisting of the four linear strain gages, model N2A-XX-S5262P-350/E4 and nominal resistance of 350 Ω, from the company Micro-Measurements, which showed accuracy of 98%. The mechanical structure also has a stainless-steel support that measures 1 cm thick and 3 cm wide located at the bottom and on which was glued a cushion to support the palm of the hand. This support can be replaced by other models that also contain a cushion that considers the presence of injuries or deformities in the hand. The mechanical structure also has a upper support that also measures 1 cm thick and 3 cm wide, to which four pressure sensors developed with rosette strain gages model N2K-XX-S5294R-350/DP/E4 with a nominal resistance of 350 Ω, from the company Micro-Measurements, were fixed and which showed an accuracy of 99.5%. The deformation sensor is stimulated by the application of palmar grip strenght while the pressure sensors are stimulated by the realization of index, middle, annular and minimum finger gripping strenght. In addition, these sensors are connected to Wheatstone Bridges whose feeds and also the responses are processed by five signal conditioning circuits developed with operational amplifiers LF 356, OPA 27 and OP27 GP of the company Burr-Brown, whose structure consists of voltage oscillator, amplifier, band pass filter, buffer and peak detector that generates DC voltage that feeds the data acquisition board. The answers on this board are sent to the Inspiron 15 3000 microcomputer from Dell, which has installed Labview software from National Instruments, which processes the information, stores, plotts the palmar grip strenght and pinch grip strenght graphs and can also send the information over the Internet. This research has the potential to obtain accurate information on the effects of leprosy in the hand that can support the evaluation, diagnosis of health professionals, follow up the evolution of the disease and the treatment adopted.