Statements of Income (Unaudited) - USD ($)
 3 Months Ended 9 Months Ended
Dec. 31, 2021
Sep. 30, 2021
Jun. 30, 2021
Dec. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Dec. 31, 2021
Dec. 31, 2020
Revenue $ 6,290,809     $ 6,533,362     $ 20,267,433 $ 15,503,409
Cost of sales 1,385,006     1,075,048     4,698,720 2,852,757
Gross profit 4,905,803     5,458,314     15,568,713 12,650,652
Expenses                
Research and development 596,492     702,216     2,112,630 2,399,164
Selling, general, and administrative 272,159     311,356     1,221,893 1,024,549
Total expenses 868,651     1,013,572     3,334,523 3,423,713
Income from operations 4,037,152     4,444,742     12,234,190 9,226,939
Interest income 283,940     365,498     868,519 1,166,102
Income before taxes 4,321,092     4,810,240     13,102,709 10,393,041
Provision for income taxes 855,685     884,531     2,411,228 1,833,127
Net income $ 3,465,407 $ 3,646,507 $ 3,579,566 $ 3,925,709 $ 2,222,340 $ 2,411,865 $ 10,691,481 $ 8,559,914
Net income per share – basic (in dollars per share) $ 0.72     $ 0.81     $ 2.21 $ 1.77
Net income per share – diluted (in dollars per share) 0.72     0.81     2.21 1.77
Cash dividends declared per common share (in dollars per share) $ 1.00     $ 1.00     $ 3.00 $ 3.00
Weighted average shares outstanding                
Weighted average common shares outstanding – basic (in shares) 4,833,604     4,833,232     4,833,356 4,834,324
Diluted (in shares) 4,835,770     4,833,261     4,835,781 4,834,411
Product [Member]                
Revenue $ 5,916,790     $ 6,332,349     $ 19,500,567 $ 14,850,157
Contract Research and Development [Member]                
Revenue $ 374,019     $ 201,013     $ 766,866 $ 653,252